Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BEhF~CO1~ITAINED ASSAY DEVICE AND METHOD
FIELD OF T8E INVEl~ffION
The present invention relates generally to a self-
contained assay device, which is capable of detecting various
analytes, including bioanalytes, in specimens, for example,-
from biological sources. More particularly, the present
invention relates to a self-contained disposable assay device
that may be hand held for a rapid and convenient detection of
to analyte{s) by the use of a specific binding pair, such as
antibody/antigen, polynucleotide/complementary
polynucleotide, ligand/receptor, enzyme/substrate and
enzyme/co-factor, etc. The present invention further relates
to a method of using the self-contained assay device, either
i5 in a hand-held or automated mode.
BACICQrROTJND OF THE INVENTION
In testing blood or other fluid samples for medical
evaluation and diagnosis, a rapid and simple assay is usually
20 needed by medical professionals. Over the years, various
devices and methods have been developed for assaying analytes
in specimens of biological origin.
U.S. Patent No. 4,522,923 discloses an apparatus
containing a test tube with at least three chambers each
25 containing different chemicals, including a solid sphere, and
separated from each other by a water-soluble barrier.
U.S. Patent No. 4,623,461 discloses a transverse
flow diagnostic device containing absorbent means associated
with the peripheral zone of a filter.
30 U.S. Patent No. 4,608,231 discloses a self-
contained reagent package device containing a plurality of
wells in the support member.
U.S. Patent No. 4,769,333 discloses a personal,
disposable hand held diagnostic kit having specimen support
35 member. The specimen support member carries a plurality of
receptacles for containing liquid materials. The receptacles
are later cut in sequence to release the liquid.
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U.S. Patent No. 4,837,159 discloses an automatic
chemical analyzer including a turntable rotated
intermittently at a constant pitch and holding a number of
reaction vessels.
U.S. Patent No. 4,857,453 discloses a device for
conducting an immunoassay containing a means in the housing=
for introducing a sample into the device and a self-contained
liquid reagent in a breakable container.
U.S. Patent No. 4,859,421 discloses a disposable
i0 antigen concentrator and detector containing a reagent
storage chamber connected to the reaction chamber through a
valve means which allows fluid flow from the reagent chamber
to the reaction chamber.
U.S. Patent No. 4,859,419 discloses an apparatus
i5 for immunoassay of multiple samples of biological fluids
containing a frame having plural test vessels.
U.S. Patent No. 4,918,025 discloses a self-
contained immunoassay element including a capillary
containing a fixed reagent in fluid communication with
20 reagent reservoirs.
U.S. Patent No. 4,978,502 discloses a device
containing a molded, flexible blister having an open side and
a structure for rupturing the blister closure in response to
relative motion between the blister and test specimen support
25 members.
U.S. Patent No. 4,981,786 discloses a multiple port
assay device containing a housing means for capturing a first
member of a specific binding pair in a zone and for allowing
liquid to be transported by capillary action away from the
30 zone.
U.S. Patent Nos. 4,978,504 and 5,078,968 disclose a
specimen test unit containing a specimen collecting swab and
a reagent-containing ampoule in cylindrical housing which can
be bent or squeezed or otherwise deformed to fracture a
35 reagent-containing ampoule.
U.S. Patent No. 5,137,808 discloses a liquid
reagent in a breakable container utilized for the
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determination of an analyte in a sample, and liquid reagents
in a container which pass into a second container when a seal
is ruptured.
U.S. Patent No. 5,147,780 discloses an apparatus
for the detection of analytes containing a liquid medium
restrained from a sample absorbing nib by a frangible barrier
which is broken allowing the nib to drop into the liquid
medium.
U.S. Patent No. 5,162,237 discloses an analytical
reaction cassette for performing sequential analytical assays
by noncentrifugal and noncapillary manipulations.
U.S. Patent No. 5,162,238 discloses a test carrier
for the analysis of a sample liquid containing a sample
application zone, a covering mesh, an erythrocyte separation
layer, two reagent layers and a liquid transport layer made
of an absorbent material.
U.S. Patent No. 5,164,318 discloses an automatic
analyzer for performing immunoassays containing a sample
carrying rotary disk supporting rotation of a plurality of
sample cups for containing a sample.
U.S. Patent No. 5,169,789 discloses a self-
contained solid phase immunodiffusion assay containing a tube
having a sample collector and compartmentalized reagents
separated by seals which can be broken through pressure on
the sample collector, mixed with reagent, and pushed into a
ligand receptor reaction area.
There still remains a need in the art for a self-
contained, inexpensive, disposable assay device for detecting
an analyte member of a specific binding pair. More
specifically, there is a need for an assay device that can be
used easily and effectively by untrained personnel,
preferably without the need for complex additional
instruments to complete the detection of analyte. The
present invention provides such an economical, compact, easy
to operate and self-contained assay device for detecting an
analyte in a sample, such as a biological sample, which meets
the requirements.
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SOM1LARY Ol' THE INVE~1TION
The present invention relates to a self-contained
assay device capable of detecting various analyte(s),
including bioanalytes, in specimens from various sources such
as a biological source, an ecological or environmental
source, a toxic industrial source, etc. The assay device has
a first housing and a specimen holder rotatably fit in the
first housing. The specimen holder has a center portion
surrounded by a circular flange and a pin member extending
from underneath of the center portion. The center portion
has a radial slot for holding a spring/latch assembly
therein. The spring/latch assembly has a spring member, a
latch member with a remote end and a plurality of plunger
members.
The self-contained assay device according to the
present invention also includes a second housing fixedly fit
in the first housing. The second housing is preferably in
the form of a cam-plate and has a rim portion surrounding a
concave portion adapted to accommodate the center portion of
the specimen holder. The cam-plate also includes an opening
on the rim portion for adding a specimen to be tested into
the assay device.
The cam-plate has a plurality of cam-shaped
chambers provided in its rim portion and communicating with
the concave portion. Each chamber has an apex portion
located furthest away from the concave portion and a cam side
extending from the apex portion toward the next chamber. An
inner bore member communicates with the apex portion of each
chamber and extends radially into the rim portion terminating
at a dead end. The inner bore member holds a predetermined
reagent or wash solution at its dead end and is sealed by one
of the plunger members of the spring/latch assembly. The
plunger member is at least partly held in the inner bore
member and adapted to be slidely fit in the inner bore
member. The cam-plate also has an outlet provided near its
dead end for releasing the reagent contained in the inner
bore member onto the circular flange of the specimen holder.
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The outlet can have an enlarged bottom forming a recess to
prevent capillary action.
The plunger member has a sealing end fit in the
bore member in a water-tight fashion and a guiding shoulder
slidely fit in the bore member. In addition, the latch
member can have a traverse handle which extends out of the =
cam-plate through a center hole thereon.
When the specimen holder is rotated relative to the
cam-plate, the remote end of the latch member moves along the
l0 rim portion and thrusts into each chamber. The spring member
then drives the latch member radially outward and the latch
member, in turn, forces the plunger member further into inner
bore member to dispense the reagent or wash solution
contained therein. The reagent can thus be released, through
the outlets, onto the specimen holder to react with a
specimen added in advance to test for the presence of an
analyte in the specimen. Any excess fluid can be absorbed by
a blotter member inserted between the first housing and the
bottom of the specimen holder. In a preferred embodiment, a
membrane member, is positioned on the specimen holder and the
reagent is released onto the membrane member holding the
specimen on the specimen holder.
The first housing, the specimen holder, the latch
member, the plunger member and the cam-plate of the assay
device can all be made of clear or transparent plastic
material, including, but not limited to, such acrylic. As
will be understood by those skilled in the art, any polymeric
plastic material that is water-tight and can be easily molded
is suitable for fabricating the above-mentioned components.
The advantage of using a transparent material is that it is
easy for the user to visually observe the results) of
reactions carried out in the assay device with an unaided
eye. In one embodiment, the above-mentioned components are
made of colored plastic. In addition, the specimen holder
can be made of translucent or cloudy plastic.
Alternatively, any one or more of the first
housing, the specimen holder, the latch member, the plunger
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member and the cam-plate of the assay device can be made of
clear colored or cloudy or opaque colored plastic material.
If the cam-plate is of cloudy or opaque material, the cam-
plate further includes a second opening, preferably a through
hole on the rim portion, i.e., an observation hole,
positioned at or above or preferably aligned with the end -
position (described herein below) so that when the specimen
holder has been rotated to the end position, the results can
be observed through the observation hole to determine the
i0 presence or absence of analyte(s) in the specimen. The
observation hole can be fitted with a cover which can be
removed to permit observation of the results, either via the
unaided eye or by means of appropriate instrumentation, and
which can be replaced afterwards to completely seal the
i5 specimen and reagents within the used self-contained assay
device before disposal.
The self-contained assay device of the present
invention can further comprise first and second retainer
members which are located in the rim portion of the cam-plate
20 and determine a start position and an end position of the
assay device. The first retainer member and the opening of
the cam-plate through which a specimen is introduced into the
device are preferably located in the same radial direction.
In a preferred embodiment, the first and second retainer
25 members are pitch and slot members.
The number of the cam-shaped chambers can be from 2
to 8 and preferably from 4 to 6. In a preferred embodiment,
there are four cam-shaped chambers. The apex portions of
these chambers and the first and second retainer members are
30 evenly distributed along the rim portion.
The assay device can also comprise a receptacle
adapted to be attached to the opening of the cam-plate for
introducing a specimen into the assay device. A knob member
is used to provide grip mechanism for the rotation of the
35 assay device. The knob member has a center hole for fixedly
fitting onto the pin member of the specimen holder. In
addition, the remote end of the latch member can be a curved
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tip portion to facilitate the relative rotation between the
specimen holder and the cam-plate. The spring member is a
compressed spring.
In another embodiment, the assay device includes a
first housing and a specimen holder rotatably fit in the
housing. The specimen holder has a center portion, a -
circular flange surrounding the center portion and a pin
member extending from underneath of the center portion. The
center portion has a radial slot extending from its
peripheral toward its center. A spring/latch assembly is
adapted to be held in the slot on the specimen holder and
includes a spring member disposed near the center of the
center portion and a latch member having a remote end.
The self-contained assay device according to the
present invention also includes a second housing fixedly fit
in the first housing. The second housing is preferably a cam
plate and has a rim portion surrounding a concave portion
adapted to accommodate the center portion of the specimen
holder. The cam plate also includes an opening on the rim
portion for adding a specimen to be tested. A plurality of
cam-shaped chambers are provided in the rim portion and
communicate with the concave portion. Each cam-shaped
chamber has an apex portion located furthest away from the
concave portion and a cam side extending from the apex
portion toward the next chamber. When the specimen holder is
rotated relative to the cam plate, the remote end of the
latch member moves along the rim portion and can be thrust
into each chamber to break open a reagent packet to release a
reagent or wash solution contained therein for use in testing
for the presence of an analyte in a specimen.
The cam plate, the specimen holder, the latch
member and the housing of the self-contained assay device can
all be made of clear or transparent material, such as
acrylic. The advantage of using such a transparent material
is that it is easy for the user to observe the reactions
carried out in the assay device. In a preferred embodiment,
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the above-mentioned components are made of color plastic.
Moreover, the specimen holder can be made of cloudy plastic.
The self-contained assay device of the present
invention can further comprise first and second retainer
members which are located in the rim portion of the cam plate
and determine a start position and an end position of the -
assay device. The first retainer member is preferably
located in the same radial direction of the opening of the
cam plate. In a preferred embodiment, the first and second
retainer members are nitch and slot members.
The number of the cam-shaped chambers can be from 2
to 8 and preferably from 4 to 6. In a preferred embodiment,
there are four cam-shaped chambers. The apex portions of
these chambers and the first and second retainer members are
evenly distributed along the rim portion.
The self-contained assay device of the present
invention can further comprise a blotter member inserted
between the bottom of the housing and the specimen holder. A
receptacle can be adopted to be attached to the opening of
2o the cam plate for introducing a specimen into the assay
device. A knob member is used to provide grip mechanism for
the rotation of the assay device. The knob member has a
center hole for fixedly fitting onto the pin member of the
specimen holder. In addition, the remote end of the latch
member can be a curved tip portion to facilitate the relative
rotation between the specimen holder and the cam plate. The
spring member is a compressed spring.
In a preferred embodiment, each chamber has a
recess portion at its apex portion for retaining a capsule
therein. Alternatively, a retaining plate can be used which
has a hallowed-out center and adapted to fit onto the
circular flange of the specimen holder. The retaining plate
has a through hole and a plurality of recess portions
corresponding to the opening and the apex portions of the cam
plate. The recess portions on the retaining plate are
adapted to retain capsules therein.
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The present invention further relates to a method
for detecting an analyte in a specimen. The detecting method
comprises the steps of: (a) providing a self-contained assay
device, e.g. assay device 1, as described herein, (b) adding
5 a specimen of a predetermined quantity into the assay device
through the opening on the cam-plate, (c) rotating the
specimen holder relatively to the cam-plate to move the
spring/latch assembly from a start position toward a first
chamber till the spring/latch assembly enters the first
10 chamber and its associated bore member to dispense a reagent
sealed therein, (d) rotating the specimen holder relatively
to the cam-plate to move the spring/latch assembly to the
next chamber to dispense a reagent or wash solution retained
therein, (e) repeating the above step (d) till the
i5 spring/latch assembly reaches the last chamber and dispenses
a reagent or wash solution retained therein, (f) rotating the
specimen holder relatively to the cam-plate to move the
spring/latch assembly from the last chamber to an end
position and (g) observing the results to determine the
Z0 presence or absence of the analyte(s) in the specimen.
Rotation of the specimen holder can be accomplished manually
or by means of an automated operating apparatus. Observation
of the results can also be accomplished either by eye or by
means of an automated reader.
25 The present invention also relates to a method for
detecting an analyte in a specimen. The detecting method
comprises the steps of: (a) providing a self-contained
assay device as described herein above,
(b) adding a specimen of a predetermined quantity into the
30 assay device through the opening on the cam plate,
(c) rotating the specimen holder relatively to the cam plate
to move the spring/latch assembly from a start position
toward a first chamber till the spring/latch assembly reaches
the first chamber to break a capsule retained therein
35 releasing a reagent or wash solution contained within the
capsule, (d) rotating the specimen holder relatively to the
cam plate to move the spring/latch assembly to the next
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chamber to break a capsule retained therein releasing a
reagent or wash solution contained within the capsule,
{e) repeating the above step (d) till the spring/latch
assembly reaches the last chamber and breaks a capsule
retained therein, (f) rotating the specimen holder relatively
to the cam plate to move the spring/latch assembly from the=
last chamber to an end position and {g) observing the results
to determine the presence or absence of the analyte(s) in the
specimen.
BRIEF DESCRIPTION OF T8E DRAWINGS
These and other features, aspects, and advantages
of the present invention will become much more apparent from
the following description, appended claims, and accompanying
drawings, in which:
Figs. la and 1b are a top view and a cross-section
of a preferred embodiment of the self-contained assay device
according to the present invention;
Figs. 2a and 2b are partial enlarged views of the
self-contained assay device in Figs. la and ib;
Figs. 3a and 3b are a top view and a cross-section
of an alternative preferred embodiment of the self-contained
assay device according to the present invention;
Figs. 4a and 4b are top and side views of the first
housing in the self-contained assay device in Fig. 3;
Figs. 5a and 5b are top view and cross-section of
the specimen holder in the assay device in Fig. 3;
Figs. 6a to 6c show various membrane members and
Fig. 6d is a side view of the specimen holder with the
membrane member of Figs. 6a to 6c attached to it;
Figs. 7a and 7b are top and side views of the ram
member in the assay device in Fig. 3;
Fig. 8 is a cross-section of the plunger member in
the self-contained assay device shown in Fig. 3;
Figs. 9a to 9d are cross-section, bottom view and
partial enlarged views of the cam-plate in the assay device
in Fig. 3;
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Figs. l0a and lOb are top and side views of the
knob member in the assay device in Figs. 1 and 3;
Fig. 11 is a top view of the blotter member in the
self-contained assay device in Figs. 1 and 3; and
Figs. 12a and 12b are partial enlarged views of the
self-contained assay device in Figs. 3a and 3b showing the =
loaded position and the dispensed position respectively.
Fig. 13 is a cross-section of another preferred
embodiment of a self-contained assay device of the present
1o invention;
Figs. 14a and 14b are top and side views of the
first housing in the self-contained assay device in Fig. 13;
Figs. 15a and 15b are top and cross-section views
of the specimen holder in the assay device in Fig. 13;
Figs. 16a and 16b show a plane view of the membrane
member and a side view of the specimen holder with the
membrane member attached to it;
Figs. 17a and 17b are top and side views of the
latch member in the self-contained assay device in Fig. 13;
Figs. 18a and 18b are top and side views of the
cam-plate in the self-contained assay device in Fig. 13;
Fig. is is a top view of the retaining plate in the
self-contained assay device in Fig. 13;
Figs. 20a and 20b are top and side views of the
knob member in the self-contained assay device in Fig. 13;
and
Fig. 21 is a top view of the blotter member in the
self-contained assay device in Fig. 13.
DETAILED DESCRIPTION OF THE PREFERRED EMHODIMENTB
Various self-contained assay devices embodying the
principles of the present invention are illustrated in Figs.
1-21. Such self-contained assay devices have a compact
structure and are inexpensive to make. Therefore, they can
be easily carried for conducting rapid detection of
analyte(s) on site. The self-contained assay device can be
conveniently discarded after use. In each embodiment, the
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same elements are designated with the same reference numerals
and repetitive descriptions are omitted.
Figs. la through 3b show different embodiments of a
self-contained assay device 1 of the present invention. The
assay device 1 has a first housing 10 for encasing a specimen
holder 20. The specimen holder 20 holds a spring/latch -
assembly 30 (Fig. 3b), which is adapted to move radially in
the assay device 1. The spring/latch assembly 30 includes a
spring member 32, a latch member 34 and a plurality of
1o plunger members 47. A second housing 40, preferably a cam-
plate, is tightly fit within the first housing 10 and thus
fixed thereto, while the specimen holder 20 is rotatable
relative to the first and second housings 10 and 40. The
cam-plate 40 has a plurality of chambers 46 each having an
inner bore member 41 containing a reagent or wash solution 90
therein. Each inner bore member 41 has an outlet 45, through
which the reagent or wash solution 90 can be dispensed onto
the specimen holder 20, preferably onto a membrane member 29
fixed to the specimen holder 20 as described later. The cam-
plate 40 also has an opening 54 thereon for introducing a
specimen into the assay device 1.
As shown in Figs. 4a and 4b, the first housing 10
of the self-contained assay device 1 consists of a bottom
plate 12 and an upstanding wall 14. The upstanding wall 14
has a height so that the first housing 10 can accommodate
both the specimen holder and the cam-plate 40 as will be
described later. Preferably, the bottom plate 12 has a
circular shape and thus the upstanding wall 14 is also
circular. A through hole 16 is formed in the center of the
bottom plate 12 for passing a pin member 24 on the specimen
holder as will be described later.
In a preferred embodiment, the first housing 10 has
a through hole 18 thereon. Such a through hole 18 is
designed for the user to observe the final result of the
assay reactions. As will be described hereinafter, the
through hole 18, together with other openings or apertures on
the second housing, the specimen holder and the blotter
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member is particularly useful when these components are non-
transparent.
Further, the first housing 10 of the assay device 1
can optionally have an orientating device 15 provided at its
bottom. The orientating device 15 is adapted to engage with
a complemental orientating device on an automatic operating=
apparatus to thus ensure the first housing 10 is properly
positioned in the operating apparatus for an automated
operation as will be described later. In an embodiment, the
orientating device 15 on the first housing 10 is in the form
of a recess member, which is engagable with a key member on
the operating apparatus.
The first housing 10 of the assay device I can be
made of various materials and by various processes.
Materials, such as plastics, are preferred for their
inexpensive cost and non-erosive features. In an embodiment,
the first housing 10 is molded or otherwise fabricated of
clear or transparent plastic material. Acrylic is one
illustrative non-limiting example of a suitable plastic
material. As will be understood by those skilled in the art,
any of a number of other polymeric plastic materials are
suitable for fabricating the assay device of the present
invention. One advantage of using such a transparent plastic
material is that it is easier for the user to visually
observe, with an unaided eye, the elements housed in the
first housing l0 and to determine whether a chemical reaction
or binding has occurred in the assay device 1.
The specimen holder 20, as shown in Figs. 5a and
5b, is in the shape of a circular plate 22 with a pin member
24 extending from underneath and at the center thereof. The
circular plate 22 is dimensioned to be loosely fit and freely
rotatable inside the upstanding wall 14 of the first housing
10 after assembling. The specimen holder 20 can also be made
of various materials and by various processes. Similar to
that with the first housing 10, materials, such as polymer
plastics, are preferred for making the specimen holder 20.
In an embodiment, the specimen holder 20 is molded of clear
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acrylic either with or without color. Moreover, the specimen
holder 20 can be made of translucent or cloudy plastic.
The circular plate 22 of the specimen holder 20 is
stepped to form a center portion 22a and a circular flange
22b surrounding the center portion 22a. The center portion
22a has at least one slot 26 extending radially from its -
periphery toward its center for accommodating a spring/latch
assembly 30 as will be described later. The slot 26 has a
closed end 26a and open end 26b near the periphery of the
center portion 22a. The number of the slot 26 can be one or
more depending on the nature of the test assays to be
performed using the assay device 1.
One main function of the circular flange 22b is to
hold the specimen to be examined suspected of containing one
or more analyte(s) and/or other reagents. As described
later, the added specimen is deposited on the circular flange
22b of the specimen holder 20 at a position to which the slot
26 opens. Such a position is designated by reference numeral
28 in Fig. 5a. In a preferred embodiment as shown in Fig.
5b, the position 28 has pores or channels to allow liquid to
pass therethrough. In this manner, any unbound specimen or
excess reagent (or wash solution) 90 can pass through
position 28 of the specimen holder 20 after each reaction or
washing process and be deposited on a blotter member 80 as
will be discussed hereinafter.
In an alternative embodiment, a membrane member 29
(Fig. 6) can be provided on the circular flange 22b of the
specimen holder 20 at position 28, as shown in Fig. 6d. The
membrane member 29 is made of a porous material including but
not limited to such as nitrocellulose, etc. In addition, the
position 28 on the specimen holder 20 has pores or channels
similar to those described above to allow liquid to pass
therethrough. Thus, unbound specimen or reagent or wash
solution 90 is allowed to pass through the membrane member 29
and position 28 onto the blotter member 80, while the bound
specimen or reagent 90 is immobilized by the membrane member
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29 for subsequent reaction or examination as will be
described hereinafter.
The membrane member 29 can be retained in place
through various conventional methods such as adhesion,
embedment, insertion, etc. In the preferred embodiment as
shown in Fig. 6d, the circular flange 22b of the specimen -
holder 20 has a cut-out portion 28' at position 28. The cut-
out portion 28' can be in the form of a through hole. Thus,
the membrane member 29 can be inserted in the cut-out portion
to or the through hole 28' and retained therein.
In certain embodiments, the membrane member 29 can
immobilize one member of a specific binding pair, which is
complementary to the analyte(s) to be detected, on a portion
29b (Fig. 6a) of the membrane member 29 to serve as a
"capture site" for any analyte in the specimen. For example,
if the analyte to be detected is an antibody, the antigen to
which the antibody binds specifically can be immobilized on a
predetermined area or zone, 29b, of the membrane member 29.
As another example, if the analyte to be detected is an
antigen, an antibody to which the antigen binds specifically
can be immobilized on a predetermined area or zone, 29b, of
the membrane member 29. In either mode of this embodiment,
the first bore member contains a wash solution and the
remaining members contain reagents and/or wash solution, for
the signal system.
Further, the membrane member 29 can be used to
immobilize not only the specimen and/or a member of the
specific binding pair but also one or more reagents which can
serve as a positive or negative control. For a positive
control, the membrane member 29 has a predetermined amount of
the analyte(s) to be detected immobilized on a predetermined
area or zone 29b of the membrane member 29. For a negative
control, the membrane member 29 has a predetermined amount of
a substance to which the analyte does not bind specifically
immobilized on a predetermined area or zone 29b of the
membrane member 29.
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Fig. 6a shows a number of areas or zones 29b at
which the appropriate substance to serve as a positive or
negative control and other tests can be immobilized. The
areas or zones 29b shown in Fig. 6a are presented for
illustrative purposes only and, as will be understood by
those skilled in the art, the size and configuration of the=
areas or zones 29b is a matter of design choice.
In a preferred embodiment as shown in Fig. 6b, the
areas and zones 29b are configured as signs "+~' and "-'~ and
letters "Me", "Mu" and "Ru". These signs and letters
represent the different substances bound on the areas and
zones 29b of the membrane member 29, such as those used for
positive and negative control, measles antigen, mumps antigen
and rubella antigen as in an embodiment described
hereinafter. Such signs and letters can directly reflect the
assay reactions occurred at the areas and zones 29b and
thereby make it easier for the user to identify or determine
which analyte(s) (e.g., antibodies) are present in the
specimen tested.
In another preferred embodiment as shown in Fig.
6c, the areas and zones 29b are configured as signs "+" and
"-" and numbers such as "10", "50" and "100". Similar to
those in the above embodiment, the signs are to represent the
specific substances bound on the membrane member 29 which are
used for positive and negative control. The numbers, on the
other hand, are used to represent the amount of the same
substance, such as an antigen, bound on the areas and zones
29b of the membrane member 29. Depending on the color change
at these areas and zones 29b after the assay reaction, the
numbers can assist in determining the amount of a specific
analyte (e. g., antibody) in the specimen tested.
In addition, the number of areas or zones 29b
depends upon the number of analytes to be assayed using the
device. For example, as shown in Fig. 6a, the areas or zones
29b can have immobilized positive control reagents for 5
different assays. Alternatively, the zones or areas 29b can
have immobilized one substance for a negative control and 4
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positive control reagents. Fig. 6a is presented for
illustrative purposes only and the determination of the size,
number and configuration of the areas or zones 29b are well
within the skill in the art.
Additionally, the membrane member 29 can be
configured so that the portions of the membrane member 29 -
represented by the areas or zones 29b can be properly
oriented in a predetermined orientation. In a preferred
embodiment, a cut-out portion 29a (Figs. 6a to 6c) can be
provided on the membrane member 29 so that it can be properly
oriented during manufacturing and assembling. Other
orientating mechanism as can be contemplated by those skilled
in the art can also be used.
The spring/latch assembly 30 (see Fig. 3b) has a
spring member 32 and a latch member 34, both adapted to be
fit in the slot 26 on the specimen holder 20. The spring
member 32 is disposed at the closed end of the slot 26 of the
specimen holder 20 while the latch member 34 is arranged
adjacent to the spring 32 and has a remote end 36 pointing
outwardly. The remote end 36 engages a plunger member 47
during the operation of the assay device 1 as will be
discussed later. The spring member 32 is preferably a
compressed spring and kept in its compressed state before
use.
In an alternative embodiment as shown in Figs. 3a
and 3b, the latch member 34 has a traverse handle member 34a
formed thereon, which is further illustrated in Figs. 7a and
7b. After assembling, the handle member 34a extends out of
the cam-plate 40 through a center hole 51 provided on the
cam-plate 40, as shown in Figs. 3a and 3b. When the
spring/latch assembly 30 drives the plunger member 47 further
into the bore member 41, the remote end 36 of the latch
member 34 may also enter the bore member 41. In this case,
the handle member 34a can be pulled to withdraw the remote
end 36 of the latch member 34 back into the chamber 46.
Thereby, a continuous operation of the self-contained assay
device 1 can be performed. In addition, the remote end 36 of
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the latch member 34 can have a ramp portion 36a to assist its
easy withdrawal to the chamber 46 and smooth advancement to
the next chamber 46.
In an alternative embodiment, the center hole 51 is
so sized that it can effectively limit the advancement of the
handle member 34a. As a result, the remote end 36 of the -
latch member 34 is blocked from entering the bore member 41
by accident. Moreover, the handle member 34a can assist in
withdrawing the spring/latch assembly 30 back to its
io compressed position. Thereby, the self-contained assay
device 1 is prepared for the next test step. It is
understood that this embodiment is preferred to be used for
manual operation of the assay device 1.
The spring/latch assembly 30 also has a plurality
of plunger members 47 retained partly in the inner bore
member 41 of the cam-plate 40. Each plunger member 47 is
adapted to be slidely fit in each bore member 41 and extend
into the chamber 46 of the cam-plate 40. The plunger member
47 cooperates with the latch member 34 and the spring member
32 to dispense the reagent or wash solution 90 contained in
the inner bore member 41 during the operation of the self-
contained assay device 1.
In a preferred embodiment as shown in Fig. 8, the
plunger member 47 has a guiding shoulder 47a and a sealing
end 47b. The guiding shoulder 47a is sized and adapted to
slidely guide the plunger member 47 inside the bore member
41. Moreover, the sealing end 47b of the plunger member 47
is slidely fit inside the bore member 41 in a water-tight
fashion. Thus, a predetermined quantity of reagent (or wash
solution) can be sealed in the bore member 41 between the
dead end 43 and the sealing end 47b of the plunger member 47.
Figs. 9a through 9d show various details of the
second housing 40, preferably a cam-plate. The cam-plate 40
is configured as a circular disk made of plastic material,
such as clear acrylic, etc. The peripheral of the cam-plate
is dimensioned to be tightly fit in the upstanding
circular wall 14 of the first housing 10. There is a concave
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portion 42 formed on the underside of the cam-plate 40 which
is surrounded by a rim portion 44 of the cam-plate 40. The
concave portion 42 is adapted to accommodate the center
portion 22a of the specimen holder 20 while the rim portion
44 is supported on the circular flange 22b of the specimen
holder 20. In this manner, the cam-plate 40 can lay on the-
specimen holder 20 when assembled.
A plurality of chambers 46 are provided on the rim
portion 44 of the cam-plate 40 and in communication with the
concave portion 42. Each chamber 46 has a triangular shaped
portion with its bottom portion 46a merging into the concave
portion 42. The other two sides 46b and 46c of each chamber
46 extend so that they would meet at an apex 48 portion,
which is close to the peripheral portion of the cam-plate 40.
One of the two sides 46b and 46c is a radial side 46b
extending substantially radially and the other side 46c is a
cam side. Preferably, at least part of the cam side 46c of
each chamber 46 is curved to facilitate the operation of the
assay device 1 as will be discussed later. The radial sides
46b alternate with the cam sides 46c along the peripheral of
the concave portion 42 of the chambers 46.
In addition, each chamber 46 has an inner bore
member 41 provided in its rim portion 44. Each inner bore
member 41 communicates with its corresponding chamber 46 at
the apex portion 48 and extends radially outwardly to reach
its dead end 43. Each inner bore members 41 slidely engages
with at least part of a plunger member 47 and thus holds the
same therein. The inner bore member 41 and the plunger
member 47 retain a reagent (or wash solution) 90 at the dead
end 43 of the inner bore member 41 when sealingly engaging
with each other.
Preferably, the inner bore member 41 has a length
which is substantially the same as or, preferably, slightly
shorter than that of the plunger member 47. Thus, after the
plunger member 47 thrusts into the bore member 41 to dispense
the reagent (or wash solution) 90, it can still extend to the
apex portion 48 of the chamber 46. In this manner, the
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plunger member 47 can facilitate a smooth transition from the
apex portion 48 to the cam side 46c of the chamber 46. Thus,
the remote end 36 on the latch member 34 can move from the
apex portion 48 toward the next chamber 46, so that the assay
device 1 can be readily rotated for the next reaction.
An outlet 45 is provided at the lower portion of -
each inner bore member 41. Thereby, the reagent 90 can flow
therethrough and onto the specimen holder 20 or the membrane
member 29 fixed thereto to react with the specimen to be
l0 tested. Preferably, the outlet 45 is located adjacent to the
dead end 43 of each inner bore member 41 so that the reagent
contained in the inner bore member 41 can all be dispensed.
In a preferred embodiment, the outlet 45 can have an enlarged
lower portion 49, as shown in Figs. 2a and 2b. The enlarged
lower portion 49 can prevent capillary action from permitting
the premature release of reagent 90, the added specimen or
the resultant of the reaction of the two to migrate out of
the outlet 45.
In an alternative embodiment shown in Fig. 2a, the
outlet 45 is configured as a plurality of fine through holes
45'. In this manner, the reagent 90 can be forced to spray
out of the fine outlet holes 45' and be evenly distributed
onto the specimen holder 20 or the membrane member 29 to
thereby ensure a thorough reaction with the specimen.
Similar to the above preferred embodiment, each fine hole 45'
can be enlarged at its lower portion to prevent capillary
action as discussed above.
It is preferred that the cam-shaped chambers 46 are
continuously and evenly distributed along, at least a portion
of, the peripheral of the concave portion 42. The number of
chambers 46 for the self-contained assay device 1 can be up
to 6 or more depending on analysis requirements. In a
preferred embodiment shown in Fig. la, four chambers 46 are
provided. These chambers 46 are continuously arranged along
the peripheral of the concave portion 42 to occupy about 240°
arc thereof. The apex portion 48 of two adjacent chambers 46
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are spaced from each for about 60° arc of the peripheral of
the concave portion 42.
It is also preferred that at least a portion of the
periphery of the rim portion 44 is free of any cam-shaped
chamber 46 and therefore a retaining mechanism can be
provided thereon. As shown in Fig. la, a pitch member 50 and
a slot member 52 are provided along the periphery of the
concave portion 42 and in the rim portion 44. As will be
described in detail hereinafter, the pitch member 50 and the
to slot member 52 are adapted to retain the latch member 34 of
the spring/latch assembly 30 in position at the start and the
end of the operation of the assay device 1 respectively. The
pitch member 50 is located next to a radial side 46b of the
first chamber 46. The slot member 52 is located next to the
cam side 46c of the last chamber 46. In a preferred
embodiment, the pitch member 50, the slot member 52 and the
cam-shaped chambers 46 are all evenly distributed along the
peripheral of the concave portion 42.
The cam-plate 40 also has an opening 54 located on
its rim portion 44, through which a specimen to be tested is
introduced into the self-contained assay device 1. The
opening 54 is preferably aligned with the start position of
the assay device 1, as shown in Fig. la. It is also
preferred that the opening 54 and the chambers 46 are evenly
distributed along the peripheral of the concave portion 42.
In a preferred embodiment shown in Fig. la, the opening 54 is
in the form of a through hole. The arc between the through
hole 54 and its adjacent chamber 46 is also 60°. The through
hole 54 and the pitch member 50 are substantially in the same
radial direction. The through hole 54 is also adapted to
receive a receptacle 56 (Fig. lb) therein.
A filter member 57 as shown in Figs. la and 3a can
be provided with the assay device 1 to filter particulates
such as erythrocytes, aggregates, crystals, etc. from the
specimen. In an embodiment as shown in Fig. la, the filter
member 57 is affixed to the opening 54 on the cam-plate 40.
In an alternative embodiment as shown in Fig. 3a, the filter
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member 57 is designed to be assembled in the receptacle 56.
When a specimen is added into the assay device 1 through
either the opening 54 on the cam-plate 40 of the receptacle
56, the filter member 57 can remove debris or the like from
the specimen.
The cam-plate 4o can further have an observation =
port 58 (Fig. 9a) located on its rim portion 44. The
observation port 58 is preferably spaced away from the center
cam-plate 40 for such a distance that it can be aligned with
the position 28 on the specimen holder 20. Further, the
observation port 58 and the slot member 52 on the cam-plate
40 are substantially in the same radial direction. In a
preferred embodiment shown in Fig. la, the arc between the
observation port 58 and its adjacent chamber 46 is also 60°.
The observation port 58 can be in the form of a through hole.
A removable cover 59 can be provided to fit in and from the
top of the observation port 58 to seal the same.
Figs. l0a and lOb show a knob member 70, which is
provided to facilitate the rotation between the specimen
holder 20 and the cam-plate 40. The knob member 70 has a
through hole 72 therein for engaging with the pin member 24
on the specimen holder 20. The peripheral 74 of the knob
member 70 provides the user with grip mechanism in operating
the assay device 1. In a preferred embodiment, the
peripheral 74 has straight knurls 76 thereon for assisting
the user in gripping the knob member 70. Alternatively, the
peripheral 74 of the knob member 70 can be scalloped. The
configuration of the peripheral 74 of the knob member 70 can
be various shapes, such as a circle, triangle, rectangle,
pentagon and hexagon. The knob member 70 can also have an
irregular shaped peripheral 74 so long as the peripheral 74
can provide a grip mechanism.
It is preferred that the knob member 70 has a flat
bottom 78 so that, when it is attached to the axal 24 on the
specimen holder 20, the entire assay device 1 can sit on a
flat supporting surface.
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In addition, the knob member 70 can have an
orientating device 75, which is located on its bottom 78
preferably. Similar to the orientating device 15 on the
first housing 10, the orientating device 75 is adapted to
engage with a complemental orientating device on an automatic
operating apparatus to thus ensure the knob member 70 is -
properly positioned in the operating apparatus for automated
operation as will be described later. In a preferred
embodiment, the orientating device 75 on the knob member 70
I0 is in the form of a recess member, which is engagable with a
key member on the operating apparatus.
Fig. 11 shows a blotter member 80 which can be used
in the self-contained assay device 1. The blotter member 80
has a circular shape dimensioned to be tightly fit in the
upstanding wall 14 of the first housing 10. The blotter
member 80 has a center aperture 82 designed to pass the pin
member 24 of the specimen holder 20 therethrough. Thereby,
the blotter member 80 can be held between the first housing
10 and the specimen holder 20 when the assay device 1 is
ZO assembled. One main function for the blotter member 80 is to
absorb excess liquid or any liquid that may enter into the
first housing 10 and to prevent the same from leaking out of
the self-contained assay device 1.
Further, the blotter member 80 can have a through
hole 84 as shown in Fig. 11. The through hole 84 is located
near the periphery of the blotter member 80 and away from the
center of the blotter member 80 for a distance. Such a
distance is substantially the same to that the position 28 is
away from the center of the specimen holder 20. Thereby, as
the assay device 1 is rotated to its end position, the
through hole 84 on the blotter member 80 can be aligned with
the position 28 for observation purpose. The construction of
such through hole 84 is particularly applicable for the case
where the first and second housings 10 and 40 and the
specimen holder 20 are made of non-transparent materials.
When being used, such blotter member 80 is made aligned with
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the slot member 52 on the cam-plate 40 and is preferably
fixed to the first housing 10.
When assembled, the blotter member 80, the specimen
holder 20, the spring/latch assembly 30 and the cam-plate 40
are all accommodated in the first housing 10 with the cam-
plate 40 being fixedly fit within the first housing 10. The
specimen holder 20 is rotatable relative to the cam-plate 40
but retained in a start position through the engagement
between the latch remote end 36 and the nitch member 50 on
the cam-plate 40. The spring member 32 of the spring/latch
assembly 30 is thus maintained in a compressed position. In
case that the housings 10 and 40 and the specimen holder 20
are made of non-transparent materials, the observation port
58 on the cam-plate 40 is aligned with the through hole 84 on
the blotter member 80. Fluids 90 comprising various
reagents) and/or wash solutions) for the test analysis or
analyses are placed and retained at the dead end 43 of each
inner bore member 41 of the chamber 46. The receptacle 60
can be attached to the opening 54 on the cam-plate 40 for
receiving a specimen to be tested in the assay device 1.
Descriptions will now be made in relation to the
operation of the self-contained assay device 1 of the present
invention. A sufficient volume of a specimen to be tested is
introduced into the assay device 1 through the opening 54 on
the cam-plate 40 so that it covers completely or wets the
position 28 on the specimen holder 20 or the membrane member
29. In a preferred embodiment, the specimen is sprayed into
the assay device 1 and thus is evenly distributed on the
circular flange 22b of the specimen holder 20 at position 28.
In other words, the added specimen is deposited on the
membrane member 29. The specimen holder 20 is then rotated
relative to the cam-plate 40 so that the latch remote end 36
of the spring/latch assembly 30, as well as position 28 on
the specimen holder 20, leaves the start position and moves
toward the first chamber 46. During such rotation, the
spring member 32 of the spring/latch assembly 30 is
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maintained in a compressed state by the peripheral of the
concave portion 42 of the cam-plate 40.
When the latch remote end 36 arrives at the apex
portion 48 of the first chamber 46a, the compressed spring 32
5 is released from the restriction of the peripheral of the
concave portion 42. The latch member 34 thus thrusts -
radially outwardly and into the first chamber 46 to engage
the first plunger member 47 and drive the same further into
the inner bore member 41. The reagent (or wash solution) 90
10 contained at the dead end 43 of the inner bore member 41 is
thus dispensed through the outlet 45 onto the circular flange
22b of the specimen holder 20 at position 28 where the membrane
29 is attached. The reagent can thus react with the specimen
added onto membrane member 29 in advance.
i5 After the reaction, unbound specimen or reagent can
pass through the membrane member 29, and the porous position
28 on the circular flange 22b and deposit on the blotter
member s0. The bound specimen or reagent, on the other hand,
is immobilized by the membrane membsr 29 on the specimen
Z0 holder 20 for a subsequent assay reaction.
In an alternative embodiment, the unbound specimen
or reagent can be carried away by the first chamber 46a upon
further rotation of the assay device i to the next reaction
position. When the rim portion 44 and the circular flange
25 22b are water-tightly engaged. when the rim portion 44 and
the circular flange 22b do not have a water-tight engagelaent,
unbound specimen or reagent can flow therebetween and onto
the blotter member 80. The bound specimen or reagent, on the
other hand, is immobilized by the membrane member 29 on the
30 specimen holder 20 for a subsequent assay reaction.
The specimen holder 20 is then rotated again
relative to the cam-plate 40 so that the latch remote end 36
of the spring/latch assembly 30 and position 28 on tha
specimen holder 20 leave the apex portion 48 of the first
35 chamber 46a and move along the cam side 46c toward the second
chamber 46b. As the specimen holder 20 is being rotated, the
cam side 46c of the first chamber 46a pushes the latch member
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34 and, in turn, the spring member 32 of the spring/latch
assembly 30 back into the slot 26 on the specimen holder 20
and in a compressed state. The spring member 32 of the
spring/latch assembly 30 is thus ready for the next thrust.
After the spring/latch assembly 30 is forced back into the
slot 26, the result of the reaction can be easily observed -
through the transparent cam-plate 40.
The above steps are then repeated until the latch
remote end 36 of the spring/latch assembly 30 passes all the
1o cam-shaped chambers 46 and comes to the end position to
engage with the slot member 52. Thereby, the result of a
previous reaction is made to react with the reagent and/or
wash solution 90 contained in the inner bore member 41 of a
next chamber 46. In this way, the specimen is carried
through a series of reactions in an analysis for detecting
analyte(s) contained therein. The final result of the test
can be easily observed through the transparent cam-plate 40.
After the completion of the test, the self-contained assay
device 1 can be discarded and no cleaning step is necessary.
In an alternative embodiment where the housings 10
and 40 and the specimen holder 20 are not transparent,
observation of the final result can be made through the
observation port 58 on the cam-plate 40 and/or the through
holes 18 and 84 (Fig. 4a and 11) in the first housing 10 and
the blotter member 80 respectively, when the cover 59 is
removed. The cover 59 can be replaced before the assay
device 1 is discarded.
In a preferred embodiment, one or more inner bore
members 41 containing a wash solution is used in the self-
contained assay device 1. Such wash solutions 90' are
arranged similarly in the inner bore members 41 of desired
cam-shaped chambers 46. In another preferred embodiment,
wash solution 90' is arranged alternately with the reagent
90. Thereby, after each reaction of the reagent 90 and the
specimen, a wash solution 90' is dispensed to wash away any
unbound specimen or reagent. In this Way, only the bound
resultant is left at position 28 or the membrane member 29 on
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the specimen holder 20, which is to be used for the next
reaction with the reagent 90 in the inner bore member 41 of
the next chamber 46. A reagent or wash solution may be the
fluid contained in the first inner bore member. In a
preferred embodiment, a wash solution is contained in the
first inner bore member. _
In an alternative embodiment, the operation of the
self-contained assay device 1 is automated. Accordingly, an
operating apparatus (not shown) is employed, which can be any
conventional apparatus for conducting a similar operation. A
typical operating apparatus can have a first and a second
clamping members for holding the first housing 10 and the
knob member 70 of the assay device 1 respectively. The first
and second clamping members are rotatable relative to each
other through a step motor to conduct the test. In a
preferred embodiment, the first and second clamping members
each include an orientating device engagable with the
orientating devices 15 and 75 on the assay device 1. The
orienting devices on the clamping members can be in the form
of recesses or preferably keys complementary to the keys and
recesses 15 and 75 on the assay device 1. In this manner,
the assay device 1 can be properly orientated in the
operating apparatus for the benefit of utilizing a reader,
such as a bar code reader, for automatic analysis.
The operating apparatus can also have a computer
device for electronically controlling the testing operation.
The computer device is programmed so that it can control the
temperature and the time period for each reaction in the
assay device 1. In addition, the operating apparatus can
have an automatic reader to identify various test resultants
retained on the membrane member 29. The automatic reader can
be of various forms such as a bar code scanner or other types
of color reaction detectors. The automatic reader can be
linked to a computer or other device to automatically record
and store the results of the tests conducted using the assay
device, e.g., for medical records keeping.
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When using the assay device 1 of the present
invention on the operating apparatus to conduct a test, the
first housing 10 and the knob member 70 of the assay device 1
are held by the first and second clamping members of the
apparatus respectively. In a preferred embodiment, the
orientating devices on the assay device 1 and those on the
operating apparatus are made to engage with one another.
Thereby, the automatic bar code reader can align with the end
position or the observation port 58 of the assay device 1 for
i0 automatic assay and analysis.
After the assay device 1 is properly oriented and
held in the operating machine, a step motor then rotates one
of the first housing 10 and the knob member 70 step by step
so that the spring/latch assembly 30 moves from one chamber
46b to a next chamber 46b in each rotation. For each test,
the step motor only moves a predetermined number of steps,
depending on the number of steps of a particular test or the
number of chambers 46b of the assay device 1. Upon
completion of all the rotation steps, the step motor stops so
that the user can exam the test results. When the test
finishes, the operating machine releases the assay device 1
or disposes the assay device 1 as desired.
Figs. 13 through 21 show different embodiments of a
self-contained assay device 100 of the present invention..
Referring to Fig. 13, a self-contained assay device 100 of
the present invention is shown in cross-section. The self-
contained assay device 100 has a first housing 110 for
encasing a specimen holder 120 containing a spring/latch
assembly 130. A second housing 140, preferably a cam-plate,
is provided to be tightly fit with the first housing 110 and
thus fixed thereto, while the specimen holder 120 and the
second housing 140 are rotatable relative to each other. The
spring/latch assembly 130 is adapted to move radially in the
assay device 100. The cam-plate 140 has an opening 154 (Fig.
15a) thereon for introducing a specimen into the assay device
100.
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When the specimen holder 120 and the cam-plate 140
are made to rotate relative to each other, the spring/latch
assembly 130 can move radially outwardly to break a reagent
packet 190 contained in the self-contained assay device 100.
Thus, the reagent released from the packet 190 can react with
the added specimen for analysis purposes. The reagent packet
190 can be in various forms such as capsules, packets or the
like, even though Fig. 13 shows a capsule 190 in specific.
As shown in Figs. 14a and 14b, the first housing
110 of the assay device 100 consists of a bottom plate 112
and an upstanding wall 114. The upstanding wall 114 has a
height so that the first housing 110 can accommodate both the
specimen holder and the cam plate as will be described later.
Preferably, the bottom plate 112 has a circular shape and
thus the upstanding wall 114 is also circular. A through
hole 116 is formed in the center of the bottom plate 112 for
passing a pin member on a specimen holder as will be
described later.
The first housing 110 of the assay device 100 can
be made of various materials and by various processes.
Materials, such as plastics, are preferred for their
inexpensive cost and non-erosive features. In an embodiment,
the first housing 110 is molded or otherwise fabricated of
clear or transparent plastic material. Acrylic is one
illustrative non-limiting example of a suitable plastic
material. As will be understood by those skilled in the art,
any of a number of other polymeric plastic materials are
suitable for fabricating the assay device of the present
invention. One advantage of using such a transparent plastic
material is that it is easier for the user to visually
observe, with an unaided eye, the elements housed in the
first housing 110 and to determine whether a chemical
reaction or binding has occurred in the assay device 100.
In an alternative embodiment, the first housing 110
has a through hole 118 provided on its bottom plate 112 and
near its upstanding wall 114. Such through hole 118 is
designed to assist the user in observing the final result of
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the assay reactions. The through hole 118 is particularly
needed when the housings 110 and 140, the specimen holder 120
and the blotter member are non-transparent. As will be
described later, the through hole 118 and other openings or
apertures on the second housing 140 and the blotter member
are properly oriented upon assembly so that they will be _
aligned at an end position of the assay device 100.
The specimen holder 120, as shown in Figs. 15a and
15b, is in the shape of a circular plate 122 with a pin
member 124 extending from underneath and at the center
thereof. The circular plate 122 is dimensioned to be loosely
fit and freely rotatable inside the upstanding wall 114 of
the first housing 110 after assembling. The specimen holder
120 can also be made of various materials and by various
processes. Similar to that with the first housing 110,
materials, such as polymer plastics, are preferred for making
the specimen holder 120. In a preferred embodiment, the
specimen holder 120 is molded of clear acrylic either with or
without color. Moreover, the specimen holder 120 can be made
of cloudy plastic.
In the current preferred embodiment, the circular
plate 122 is stepped to form a center portion 122a and a
circular flange 122b surrounding the center portion 122a.
The center portion 122a has at least one slot 126 extending
radially from its periphery toward its center for
accommodating a spring/latch assembly 130 as will be
described later. The slot 126 has a closed end 126a located
near the center of the circular plate and open end 126b near
the periphery of the center portion 122a. The number of the
slot 126 can be one or more depending on the nature of the
test assays to be performed using the assay device.
One main function of the circular flange 122b is to
hold the specimen to be examined and/or other analyte(s) and
reagent(s). As will be described later, the added specimen
is deposited on the circular flange 122b of the specimen
holder I20 at a position at which the slot 126 opens. Such
position is designated by reference numeral 128 in Fig. 15a.
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In a preferred embodiment, at least the portion of the
circular flange 122b where position 128 is located is made of
a porous material. In this manner, any unbound specimen or
reagent can pass therethrough after each reaction or washing
process and be deposited on a blotter member as will be
discussed hereinafter.
In an embodiment, a membrane member 129 (Fig. 16a)
can be provided on the circular flange 122b of the specimen
holder 120 at position 128, as shown in Fig. 16b. The
i0 membrane member 129 is made of a porous material including
but not limited to such as nitrocellulose. Tn addition, the
position 128 on the specimen holder 120 has pores or channels
similar to those described above to allow liquid to pass
therethrough. Thus, unbound specimen or reagent is allowed
to pass through the membrane member 129 and position 128 onto
the blotter member 180, while the bound specimen or reagent
19o is immobilized by the membrane member 129 for subsequent
reaction or examination as will be discussed hereinafter.
The membrane member 129 can be retained in place
through various conventional methods such as adhesion,
embedment and insertion, etc. In the preferred embodiment as
shown in Fig. 15a, the circular flange 122b of the specimen
holder 120 has a cut-out portion 128' at position 128. The
cut-out portion 128' can be in the form of a through hole.
Thus, the membrane member 129 is inserted in the cut-out
portion or the through hole 128' and retained therein.
In certain embodiments, such as shown in Fig. 16a,
the membrane member 129 can have a plurality of areas or
zones 129b. Such areas or zones 129b are capable of
3o immobilizing one member of a specific binding pair, which is
complementary to the analyte(s) to be detected, to serve as a
"capture site" for any analyte in the specimen. For example,
if the analyte to be detected is an antibody, the antigen to
which the antibody binds specifically can be immobilized on a
predetermined area or zone, 129b, of the membrane member 129.
As another example, if the analyte to be detected is an
antigen, an antibody to which the antigen binds specifically
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can be immobilized on a predetermined area or zone, 129b, of
the membrane member 129.
Further, the membrane member 129 can be used to
immobilize not only the specimen and/or a member of the
specific binding pair but also one or more reagents which can
serve as a positive or negative control. For a positive -
control, the membrane member 129 has a predetermined amount
of the analyte(s) to be detected immobilized on a
predetermined area or zone 129b of the membrane member 129.
For a negative control, the membrane member 129 has a
predetermined amount of a substance to which the analyte does
not bind specifically immobilized on a predetermined area or
zone 129b of the membrane member 129.
Fig. 16a shows a number of areas or zones 129b at
which the appropriate substance to serve as a positive or
negative control and other tests can be immobilized. The
areas or zones 129b shown in Fig. 16a are presented for
illustrative purposes only and, as will be understood by
those skilled in the art, the size and configuration of the
areas or zones 129b is a matter of design choice.
In addition, the number of areas or zones 129b
depends upon the number of analytes to be assayed using the
device. For example, as shown in Fig. 16a, the areas or
zones 129b can have immobilized positive control reagents for
5 different assays. Alternatively, the zones or areas 129b
can have immobilized one substance for a negative control and
four positive control reagents. Fig. 16a is presented for
illustrative purposes only and the determination of the size,
number and configuration of the areas or zones 129b are well
within the skill in the art.
Additionally, the membrane member 129 can be
configured so that the portions of the membrane member 129
represented by the areas or zones 129b can be properly
oriented in a predetermined orientation. In a preferred
embodiment, a cut-out portion 129a (Fig. 16a) can be provided
on the membrane member 129 to assist in orienting the
membrane member 129 during manufacturing and assembling.
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other orientating mechanism as can be contemplated by those
skilled in the art can also be used.
The spring/latch assembly 130 consists of a spririg
member 132 (Fig. 13) and a latch member 134 (Figs. 17a and
5 17b), both adapted to be fit in the slot 126 on the specimen
holder 120. The spring member 132 is disposed at the closed
end of the slot 126 near the center of the specimen holder
120 while the latch member 134 is arranged adjacent to the
spring 132 and has a remote end 136 pointing outwardly. It
o is preferred that the spring member 132 is a compression
spring. The compression spring 132 is kept in its compressed
state before use. The remote end 136 of the latch member 134
is preferably curved to conform with a curved apex portion of
the cam-shaped chamber as will be described hereinafter and
15 therefore break a reagent packet 190 retained at the curved
apex portion more efficiently. The curved end 136 is further
cut to fona a tip portion 138 for fitting in a retaining
mechanism at start and end positions as will be described
later.
3p Digs. i8a apd 18b show the cam-plate 140, which is
configured as a circular disk made of plastic material, such
as clear acrylic. The peripheral of the cam-plate 140 is
dimensioned to be tightly fit in the upstanding circular wall
114 of the ffirst housing 110. There is a concave portion 142
Z5 formed on the underside of the cam-plate 140 which is
surrounded by a rim portion 144 of the cam-plate 140. The
concave portion 142 is adapted to accommodate the center
portion 122a of the specimen holder 120 while the rim portion
144 is supported on the circular flange 122b of the specimen
30 holder 120. In this manner, the cam-plate 140 can lay on the
specimen holder 120 when assembled.
A plurality of cam-shaped chambers 146 are provided
on the rim portion 144 of the cam-plate 140 and in
communication with the concave portion 142. It is preferred
35 that the cam-shaped chambers 146 are continuously and evenly
distributed along, at least a portion of, the peripheral of
the concave portion 142. Each chamber 146 has a triangular
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shape with its bottom portion 146a merging into the concave
portion 142. The other two sides 146b and 146c of each
chamber 146 meet at an apex 148, which is close to the
peripheral of the cam-plate 140. One of the two sides 146b
and 146c is a radial side 146b extending substantially
radially and the other side 146c is a cam side. The radial=
sides 46b alternate with the cam sides 146c along the
peripheral of the concave portion 142 of the chambers 146.
Preferably, at least part of the cam side 146c of
each chamber 146 is curved to facilitate the operation of the
assay device 100 as will be discussed later. In addition,
each chamber 146 preferably has a curved portion 149 near its
apex 148 which continues on to the radial side 146b and the
cam side 146c. In this manner, the curved apex portion 149
t5 and the cam side 146c of each chamber 146 provide a smooth
transition from the apex 148 of the chamber 146 to the radial
side 146b of the next chamber 146 as described hereinafter.
Further, the curved apex portion 149 also facilitates the
accommodation of a reagent packet 190 as will be described
hereinafter.
The number of chambers 146 for the self-contained
assay device 100 can be up to 6 or more depending on analysis
requirements. In a preferred embodiment shown in Fig. 18a,
four chambers 146 are provided. These chambers 146 are
continuously arranged along the peripheral of the concave
portion 142 to occupy about 240° arc thereof. The apexes 148
of two adjacent chambers 146 are spaced from each for about
60° arc of the peripheral of the concave portion 142.
It is also preferred that at least a portion of the
3o periphery of the rim portion 144 is free of any cam-shaped
chamber 146 and therefore a retaining mechanism can be
provided thereon. As shown in Fig. 18a, a pitch member 150
and a slot member 152 are provided along the periphery of the
concave portion 142 and in the rim portion 144. As will be
described in detail hereinafter, the pitch member 150 and the
slot member 152 are adapted to retain the spring/latch
assembly 130 in position at the start and the end of the
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operation of the assay device 100 respectively. The pitch
member 150 is located next to a radial side 146b of the first
chamber 146. The slot member 152 is located next to the cam
side 146c of the last chamber 146. In a preferred
embodiment, the pitch member 150, the slot member 152 and the
cam-shaped chambers 146 are all evenly distributed along the
periphery of the concave portion 142.
The cam-plate 140 also has an opening 154 located
on its rim portion 144, through which a specimen to be tested
is introduced into the self-contained assay device 100. A
filter member (not shown) can be affixed to the opening 154
for filtering debris or the like from the specimen. The
opening 154 is preferably aligned with the start position of
the assay device 100. It is also preferred that the opening
i5 154 and the cam-shaped chambers 146 are evenly distributed
along the periphery of the concave portion 142. In a
preferred embodiment shown in Fig. 18a, the opening 154 is in
the form of a through hole. The arc between the through hole
154 and one of its adjacent chambers 146 is also 60°. The
through hole 154 and the pitch member 150 are substantially
in the same radial direction. The through hole 150 is also
adapted to receive a receptacle 156 (Fig. 13) therein.
In a preferred embodiment as shown in Fig. 18b,
each cam-shaped chamber 146 has a recess portion 157 at its
curved apex portion 149. Such a recess portion 157 is
dimensioned to contain a reagent packet 190 such as a capsule
190 therein and thus facilitates to retain the capsule 190 in
place as will be described later.
The cam-plate 140 can further have an observation
3o port 158 (Fig. 18a) provided on its rim portionl 144. The
observation port 158 is preferably spaced away from the
center of the cam-plate 140 for such a distance that it can
be aligned with the position 128 on the specimen holder 120.
Further, the observation port 158 and the slot member 152 on
the cam-plate 140 are substantially in the same radial
direction. In a preferred embodiment, the arc between the
observation port 158 and its adjacent chamber 146 is also
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60°. The observation port 158 can be in the form of a
through hole.
Fig. l9 shows an alternative structure for retaining
reagent packet 190 in place. A retaining plate 160 is
provided which has a hollowed-out center 162 forming a donut
shape. The hollowed-out center 162 of the retaining plate
160 is adapted to loosely fit onto the center portion 122a of
the specimen holder 120 so that the retaining plate 160 lays
on top of the circular flange 122b upon assembly. An opening
portion 164 is provided on the retaining plate 160 for
passing the added specimen therethrough and onto position 128
of the specimen holder 120 at a start position of the assay
device 100.
The retaining plate 160 has a plurality of through
holes 167 thereon. Each through hole 167 corresponds to the
location of a curved apex portion 149 on the cam-plate 140
upon assembly. Thereby, the through holes 167 can assist in
retaining reagent packets, such as capsules 190, in place and
allow released reagents to pass through and onto the specimen
holder 120 at position 128. In the embodiment illustrated,
four holes 167 are formed on the retaining plate 160, each of
which can hold one reagent packet 190.
The retaining plate 160 can also have an
observation port 168 thereon, which can be aligned with
position 128 at an end position of the assay device 100. In
the embodiment as shown in Fig. 19, the observation port 168
on the retaining plate 16o is spaced away from its adjacent
through hole 167 for about 60°. The observation port 168 can
be in the form of a through hole.
Figs. 20a and 20b show a knob member 170, which can
facilitate the rotation between the specimen holder 120 and
the cam-plate 140. The knob member 170 has a through hole
172 therein which can fixedly engage with the pin member 124
on the specimen holder 120 through conventional means such as
adhesion. The peripheral 174 of the knob member 170 provides
the user with grip mechanism in operating the assay device
100. In a preferred embodiment, the peripheral 174 has
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straight knurls 176 thereon for assisting the user in
gripping the knob member 170. Alternatively, the peripheral
174 of the knob member 170 cam be scalloped. The
configuration of the peripheral 174 of the knob member 170
can be various shapes, such as circle, triangle, rectangle,
pentagon and hexagon. The knob member 170 can also have an=
irregular shaped peripheral 174 so long as the peripheral 174
can provide grip mechanism. It is preferred that the knob
member 170 has a flat bottom 178 so that, when it is attached
to the axal 124 on the specimen holder 120, the entire assay
device 100 can sit on a flat supporting surface.
Fig. 21 shows a blotter member 180 which can be
used in the self-contained assay device 100. The blotter
member 180 has a circular shape dimensioned to be tightly fit
in the upstanding wall 114 of the first housing 110. The
blotter member 180 has a center aperture 182 designed to pass
the pin member 124 of the specimen holder 20 therethrough.
Thereby, the blotter member 180 can be held between the first
housing 110 and the specimen holder 120 when the assay device
100 is assembled. One main function for the blotter member
80 is to absorb excess liquid or any liquid that may leak
into the first housing 110 and to prevent the same from
leaking out of the self-contained assay device 10.
Further, the blotter member 180 can have a through
hole 184 as shown in Fig. 21. The through hole 184 is
located near the periphery of the blotter member 180 and away
from the center of the blotter member 180 for a distance.
Such a distance is substantially the same to that the
position 128 is away from the center of the specimen holder
120. Thereby, as the assay device 100 is rotated to its end
position, the through hole 184 on the blotter member 180 can
be aligned with the position 128 for observation purpose.
The use of such through hole 184 is particularly applicable
for the case where the first and second housings 110 and 140
and the specimen holder 120 are all made of non-transparent
materials. When being used, such blotter member 180 is made
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aligned with the slot member 152 on the cam-plate 140 and is
preferably fixed to the first housing 110.
When assembled, the blotter member 180, the
specimen holder 120, the spring/latch assembly 130 and the
cam-plate 140 are all accommodated in the first housing 110.
The cam-plate 140 is fixedly fit with the first housing 110:
The specimen holder 120 is adapted to be rotatable relative
to the cam-plate 140 but retained in a start position through
the engagement between the latch tip portion 138 and the
nitch member 150 on the cam-plate 140. The spring/latch
assembly 130 is maintained in a compressed position. Reagent
packets 190 containing various reagents) and/or wash
solutions) for the test analysis or analyses are placed and
retained in the curved apex portions 149 of the chamber 146.
The receptacle 156 is attached to the opening 154 on the cam-
plate 140 for receiving a specimen to be tested in the assay
device 100.
Descriptions will now be made with regard to the
operation of the self-contained assay device 100 of the
present invention. The assay device 100 is first adjusted to
its start position where position 128 on the specimen holder
120 aligns with the opening 154 on the cam-plate 140. A
sufficient volume of a specimen to be tested is added into
the assay device 100 through the opening 154 on the cam-plate
14o so that it covers completely or wets the position 128 on
the specimen holder 120 or the membrane member 129. In a
preferred embodiment, the specimen is added into the assay
device 100 and evenly distributes on the circular flange 122b
of the specimen holder 120 at position 128. In other words,
the added specimen is deposited on the membrane member 129.
The specimen holder 120 is then rotated relatively
to the cam-plate 140 so that the spring/latch assembly 130 as
well as position 128 on the specimen holder 120, leaves the
start position and moves toward the first chamber 146.
During such rotation, the spring member 132 of the
spring/latch assembly 130 is retained in a compressed state
through the restriction exerted on tip portion 138 of the
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latch member 134 by the periphery of the concave portion 142
of the cam-plate 140.
When the spring/latch assembly 130 arrives at the
first chamber 146a where the peripheral of the concave
portion 142 discontinues, restriction on the compressed
spring 132 is released. The latch member 134 then thrusts =
radially outwardly and into the first chamber 146 till the
tip portion 138 of the latch member 134 reaches the curved
apex portion 149a of the first chamber 146a. The tip portion
138 thus breaks the capsule 90 retained thereat to release
the reagent contained in the capsule 90. The released
reagent thus flows into the first chamber 146a and deposits
on the circular flange 122b of the specimen holder 120 at the
position 128 where the member 129 is attached. The reagent
can thus react with the specimen on membrane member 129 at
position 128 on the specimen holder 120.
After the reaction, unbound specimen or reagent
will pass through the membrane member 129, and/or the porous
position 128 on the circular flange 122b and deposit on the
blotter member 180. The bound specimen or reagent, on the
other hand, is immobilized by the membrane member 129 on the
specimen holder 120 for a subsequent assay reaction.
In an embodiment where the rim portion 144 and the
circular flange 122b are water-tightly engaged, the unbound
specimen or reagent may also be carried away by the first
chamber 146a upon further rotation of the assay device 100 to
the next reaction position. Alternatively, when the rim
portion 144 and the circular flange 122b do not have a water-
tight engagement, unbound specimen or reagent can flow
therebetween and deposit onto the blotter member 180.
The specimen holder 120 is then rotated again
relative to the cam-plate 140 so that the spring/latch
assembly 130 and the position 128 on the specimen holder 120
leave the apex portion 148 of the first chamber 146a and move
along the cam side 146c toward the second. chamber 146b. As
the specimen holder 120 is rotated, the cam side 146c of the
first chamber 146a pushes the latch member 134 and, in turn,
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the spring member 132 of the spring/latch assembly 130 back
into the slot 126 on the specimen holder 120 and in a
compressed state. The spring/latch assembly 130 is thus
ready for the next thrust. After the spring/latch assembly
30 is forced back into the slot 126, the result of the
reaction can be easily observed through the transparent cam-
plate 140.
The above steps are repeated until the latch remote
end 136-of the spring/latch assembly 130 passes all the cam-
l0 shaped chambers 146 and comes to the end position to engage
with the slot member 152. Thereby, the result of a previous
reaction is made to react with the reagent and/or wash
solution (see below) contained in a next capsule 90 which is
retained in a next chamber 146. In this way, the specimen is
carried through a series of reactions in an analysis for
detecting analyte(s) contained therein. The final result of
the test can be easily observed through the transparent cam-
plate 140, or through the observation ports 118, 158, 168 and
184. After the test, the assay device 100 can be discarded
and no cleaning step is necessary.
In a preferred embodiment, one or more capsules
190' containing a wash solution, i.e., "cleaning capsules"
are used in the self-contained assay device 100. Such
cleaning capsules 190' are arranged at the curved apex
portions 149 of desired cam-shaped chambers 146. In another
preferred embodiment, cleaning capsules 190' alternate with
the capsules 190 containing reagent(s). Thereby, after each
reaction of the reagent 190 and the specimen, a cleaning
capsule 190' is broken to release a cleaning agent or wash
solution to wash away any unbound specimen or reagent. In
this way, only the bound resultant is left at the position
128 or the membrane member 129 on the specimen holder 120,
which is to be used for the next assay reaction with the
reagent in the next reagent capsule 190.
The assay devices of the present invention,
including illustrated devices 1 and 100, are useful to
determine the presence .(or absence) of an analyte in a sample
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or specimen suspected of containing the analyte. Any type of
specimen or sample in fluid form can be used, including but
not limited to biological samples such as blood, serum,
plasma, milk, urine, sweat, saliva, cerebrospinal fluid,
amniotic fluid, semen, vaginal and cervical secretions,
bronchial secretions, intestinal fluid, wound fluid (exudates
and transudatesj, thoracentesis fluid, cell or tissue
suspensions, etc., environmental samples such as water
samples, soil suspensions, etc.
As used according to the present invention, an
analyte is intended to mean any compound or composition to be
assessed which is a member of a specific binding pair and may
be a ligand or a receptor. A member of a specific binding
pair is one of two different compounds or compositions,
having an area, either on the surface or in a cavity, which
specifically binds to and is thereby defined as complementary
with a particular spatial and polar organization of the other
compound or composition. The members of a specific binding
pair are generally referred to as "ligand" and "receptor"
("anti-ligand").
As used herein, a ligand includes any compound or
composition for which a receptor naturally exists or can be
prepared. Illustrative ligands include but are not limited
to antigens; hormones; pheromones; signal substances such as
Z5 neurotransmitters, signal proteins and peptides, etc.; enzyme
substrates and cofactors; ligands for receptor proteins;
nucleic acids and polynucleotides; biotin; lectins; growth
factors or cytokines; drugs; toxins; etc.
As used herein, a receptor (anti-ligand) includes
any compound or composition which recognizes a particular
spatial and polar organization of a compound or composition,
e.g., an epitopic or determinant site or a complementary
binding site. Illustrative receptors include but are not
limited to immunoglobulins or antibodies or antigen binding
portions thereof such as Fv, F(ab~)Z, Fab fragments, single
chain antibodies, chimeric or humanized antibodies,
complementary determining regions of antibodies; hormone
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receptors; pheromone receptors; signal substance receptors;
enzymes; protein receptors; nucleic acids and
polynucleotides; avidin or streptavidin; lectin binding
proteins; growth factor or cytokine receptors; drug
receptors; etc. As will be understood easily by those
skilled in the art, nucleic acids, polynucleotides and -
oligonucleotides which are complementary to one another can
serve as the two members of a specific binding pair which can
be used in the assay devices of the present invention, one
serving as ligand and the other serving as receptor or anti-
ligand.
When the analyte to be detected is an antigen
associated with an infectious agent such as a bacterium,
fungus, virus, mycoplasma or other parasite, the assay device
of the invention can be used for the detection of infectious
disease in a patient from which the sample or specimen is
obtained. When the analyte to be detected is an antibody
against an antigen associated with an infectious agent, the
assay device of the invention can be used to detect the
presence of immunity to an infectious disease in the patient
from whom the specimen is obtained. In this instance, the
signal detected can be compared to a standard provided, and
immunity is assessed by comparison to appropriate signal,
e.g., color developed, indicating at least a minimum antibody
titer present. In one embodiment, the standard can be
provided as appropriate zones) 29b (see Figs. 6a-6c) [or
zones) 129b (see Figs. 16a)] on the membrane member. The
two above-described uses of the present device are only
illustrative examples. Numerous other uses for the assay
devices of the invention will occur to those skilled in the
art depending upon the analyte to be detected, including but
not limited to detection of the presence or absence of
particular types of cancer, genetic mutations or defects,
metabolic imbalances, drugs, toxins, pesticides, etc. and are
all within the scope of the applications or methods for using
the present invention.
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Simply for ease of description, the following
discussion is written with respect to the assay device of the
invention illustrated as device "1". The discussion is
applicable to the assay device of the invention illustrated
as "device 100". For clarity, reference to device 100 is
included in square brackets at various places in the -
discussion.
The reagents and/or wash solutions, optionally
including an ancillary material such as a buffer, stabilizer,
i0 additive to enhance binding, etc., contained in the assay
device 1 as well as the amount of reagent retained in the
inner bore member 41 of the assay device 1 [or in reagent
packet 190 of device 100] will depend upon the analyte to be
detected and is readily known to those skilled in the art.
Likewise, the reagents and/or wash solutions, optionally
including an ancillary material such as a buffer, stabilizer,
additive to enhance binding, etc., contained in the assay
device as well as the amount of reagent retained in the
reagent packets 90 of the assay device will depend upon the
analyte to be detected and is readily known to those skilled
in the art.
In all instances, there is at least one reagent 90
[or packet 190 which contains a reagent] which is
complementary to and binds specifically to the analyte(one
member of a specific binding pair) which is to be tested for
in the assay, i.e., the other member of the specific binding
pair.
In all instances, there is provided at least one or
more of the reagents which provides a signal system, such as
a color change, which indicates the presence of-the analyte
in the specimen being tested. One reagent which is a member
of the specific binding pair which binds specifically to the
analyte, i.e., second specific binding pair member, or
another molecule which binds specifically to the second
binding pair member is labelled to provide a signal system.
Suitable signal systems employ the use of an enzyme label, a
fluorescent label, a chemiluminescent label or enhanced
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chemiluminescent label, or a radioactive label, etc. Non-
radioactive labels are preferred. Suitable signal systems
are well-known to those skilled in the art. Sae, for
example, David Wild, ed., The Immunoassay Handbook, Stockton
5 Press, 1994, particularly at pages 63-77 for suitable
labels and signal generation systems useful when the
specific binding pair members are antigen and antibody (or
binding portion thereof). See, for example, George H, Keller
et al., DNA Probes, Stockton Press, 1989, particularly at
10 pages 71-148 for suitable labels and signal generation systems
when the specific binding pair members are complemeatary
polyaucleotides.
Preferred are signal systems in which a change,
15 such as in color, indicating the presence of analyte in a
specimen can be detected visually by the naked eye of the
person using the assay device under normal ambient
conditions. Alternatively, signal systems in which a change
indicating the presence of analyte in a specimen can be
Zo detected using the naked eye of the person using the assay
device aided by, for example, light of a particular
wavelength, e.g., ultraviolet light, etc. or which can be
detected using spectrophotometric or other instrumental
detection systems can be used. Less preferred is a signal
Z5 system using a radioactive label; in such instance an
appropriate device for detecting emitted radiation is used.
As one illustrative example, when the analyte to be
detected is an antigen suspected of being present in a
patient specimen, the reagents retained in the assay device 1
30 can include a capture anti-antigen antibody bound to the
reaction membrane member, a second anti-antigen antibody that
recognizes a different epitope from that recognized by the
capture antibody labelled, e.g. with an enzyme such as
horseradish peroxidase; a wash solution, and a substrate for
35 the enzyme label, e.g., 2,2'-azino-bis (ethylbenzothiazoline-
6-sulfonate) (ABTS), D-phenylenediamine (OPD) or (3,3',5,5'-
tetramethyl benzidine (TMB) (all peroxidase substrates).
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Alternatively, the reagents for such assay can include a
capture antibody, an anti-antigen antibody; a wash solution;
an anti-antibody labelled e.g., with an enzyme; a wash
solution and a substrate for the enzyme label.
As another illustrative example, when the analyte
to be detected is an antibody suspected of being present in=a
patient specimen, the reagents retained in the assay device 1
can include an antigen to which the suspected antibody binds
specifically bound to the reaction membrane member; a wash
solution; anti-immunoglobulin, e.g., human immunoglobulin,
antibody labelled e.g., with an enzyme label; a wash
solution; and a substrate for the enzyme label which when
reacted with the enzyme provides a detectable color change
indicating presence of the analyte.
i5 According to an embodiment of the present
invention, illustrated in Fig. 6a a predetermined amount of
the analyte to be detected is immobilized on a predetermined
portion of the membrane member 29, i.e., 29b, provided on the
circular flange 22b of the specimen holder 20 at position 28.
The predetermined amount of immobilized analyte reacts with
all the reagents 90 and affords a positive analyte control
that provides a positive control signal indicating that the
reagents are functioning properly and assuring the user of
the device that the assay has been successfully conducted.
The following illustrative example describes a
method for detecting an analyte which is an antigen, e.g. a
hepatitis A antigen, suspected of being present in a patient
using the self-contained assay device of the present
invention. The example is for illustrative purposes only and
is in no way intended to limit the scope of the methods of
the invention or the appended claims. As will be appreciated
by those skilled in the art, the methods for using the self-
contained assay device can be modified or changed for use to
assay for numerous other analytes and all such modifications
or changes may be practiced and are encompassed within the
scope of the appended claims.
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As an example, the method for detecting hepatitis
antigen comprises: introducing a predetermined quantity of a
specimen which is a patient blood sample into the self-
contained assay device 1 of the present invention through the
opening 54 on the cam-plate 40 which contains a filter member
57 for removing particulates, said assay device having a -
number of reagents immobilized onto separate portions of the
membrane member 29, i.e., 29b, positioned on the specimen
holder 20 onto which the blood sample is introduced. The
membrane member 29 at specific areas and zones 29b has
immobilized thereon the following substances: hepatitis A
viral antigen (positive control), unrelated protein such as
gelatin (negative control), anti-hepatitis A antibody
(capture antibody), anti-hepatitis C antibody and anti-
i5 hepatitis B antibody respectively; rotating the specimen
holder 20 relative to the cam-plate 40 to move the latch
member 34 and the spring member 32 of the spring/latch
assembly 30 from a start position toward a first chamber 46
till the latch remote end 36 reaches the apex portion 48 of
the first chamber so that the latch member 34 drives a
plunger member 47 to dispense a wash solution to wash away
any unbound material; rotating the specimen holder 20
relative to the cam-plate 40 to move the spring/latch
assembly 3o to the next chamber 46 to dispense a reagent 90
containing an anti-hepatitis A antibody that recognizes an
epitope different from the one recognized by the capture
antibody, labelled with an enzyme label; permitting the
released antibody to contact the specimen on the membrane
member for a sufficient time so that any antigen present can
bind to the enzyme labelled antibody; rotating the specimen
holder 20 relative to the cam-plate 40 to move the latch
member 34 and the spring member 32 of the spring/latch
assembly 30 to the next chamber 46 to dispense a reagent 90
retained therein releasing a wash solution; repeating the
above step till the latch remote end 36 of the spring/latch
assembly 30 reaches the next chamber 46 and dispenses a
reagent 90 retained therein releasing a substrate for the
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enzyme (label) and permitting reaction to occur between any
enzyme labelled antibody bound to the specimen holder 20 and
the enzyme substrate to provide a color change indicative of
the presence of antigen; and rotating the specimen holder 20
relative to the cam-plate 40 to move the latch member 34 and
the spring member 32 of the spring/latch assembly 30 from the
last chamber 46 to an end position; and observing the
results, comparing the color signal developed on the portion
of the membrane member 29 to which the specimen was applied
with that of the portion of the membrane member 29b on which
hepatitis A was immobilized as a positive control to
determine whether hepatitis A is present in the patient
sample.
In another embodiment, the self-contained assay
device 1 can be used to detect the presence of more than one
analyte in a sample. In a preferred mode of this embodiment
of the invention, the assay device 1 can be used to detect
the presence of a number of antibodies to a number of
infectious agents to assess whether a patient has sufficient
immunity to each of the various infectious agents.
As an illustrative example, the assay device 1 can
be used to detect antibodies against a panel of viral agents,
e.g., measles, mumps and rubella, etc. in order to assess the
status of vaccination against each such virus. A sufficient
amount of specimen is applied to wet or to cover the membrane
member 29. The membrane member 29 at specific areas or zones
29b contains the following substances: human serum
immunoglobulins (positive control), gelatin, an unrelated
protein (negative control), measles antigen, mumps antigen,
and rubella antigen, respectively. As will be understood by
those skilled in the art, the position and/or configuration
of each of the positive and negative controls and of each of
the antigens on the membrane member is identified to help
easily determine which one or more antibodies is/are present
in the specimen. See, for example, Figs. 6a-6c. The
specimen is permitted to contact the membrane member 29 for a
time sufficient for any antibody in the specimen to bind to
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the immobilized antigen(s). The first chamber 46 retains
wash solution to wash away any unbound antibody. The next
chamber 46 retains anti-human immunoglobulin labelled with an
enzyme label. The next chamber 46 retains a wash solution to
wash away any unbound labelled antibody. The next chamber 46
retains enzyme substrate, which provides a color change when
reacted with enzyme (labelled antibody). Thus, when the
assay is completed, visualization of the results is easily
provided to determine the presence or absence of each of
i0 measles, mumps and rubella antibodies in the patient
specimen.
The foregoing description is only illustrative of
the principle of the present invention. It is to be
recognized and understood that the invention is not to be
limited to the exact configuration as illustrated and
described herein. Accordingly, all expedient modifications
readily attainable by one versed in the art from the
disclosure set forth herein that are within the scope and
spirit of the present invention are to be included as further
2o embodiments of the present invention. The scope of the
present invention accordingly is to be defined as set forth
in the appended claims.
30
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