DEVICE FOR THERMAL CONVECTION POLYMERASE CHAIN REACTION

DISPOSITIF A CONVECTION THERMIQUE POUR UNE REACTION EN CHAINE DE LA POLYMERASE

English Abstract

Provided in the present invention is a device for thermal convection polymerase chain reaction (PCR). The device is used for bearing a test tube such that PCR is performed in the test tube. The device comprises a heat radiating base which has a body and a passage provided through the body to be used for the insertion of the test tube, wherein the passage has a large diameter section and a small diameter section positioned below the large diameter section. Therefore, it can be ensured that during the PCR process the surface temperature of the mixed liquid is lower than the temperature required in a primer annealing reaction.

French Abstract

La présente invention concerne un dispositif à convection thermique pour une réaction en chaîne de la polymérase (PCR). Le dispositif est utilisé pour supporter un tube à essai de sorte qu'une PCR est réalisée dans le tube à essai. Le dispositif comprend une base de rayonnement de chaleur qui a un corps et un passage présent à travers le corps destiné à être utilisé pour l'insertion du tube à essai, le passage ayant une grande section de diamètre et une petite section de diamètre positionnée au-dessous de la grande section de diamètre. Par conséquent, il peut être assuré qu'au cours du procédé de PCR, la température de surface du liquide mélangé est inférieure à la température nécessaire dans une réaction d'hybridation d'amorce.

Claims

Claims
1. A device for holding a test tube in which thermal convection polymerase
chain
reaction is performed, and for dissipating heat from the test tube, the device
comprising:
a heat dissipation base having a body provided with a passage for insertion of
the
test tube, wherein the passage has a large diameter section and a small
diameter section
located below the large diameter section;
wherein the test tube and the heat dissipation base are separated by an air
space;
the heat dissipation base dissipates heat from the test tube which is inserted
in the
passage; the heat dissipation base leaves a bottom of the test tube exposed
outside to be
heated.
2. The device of claim 1, further comprising a tube rack mounted on the
heat
dissipation base and provided with a receiving hole for insertion of the test
tube.
3. The device of claim 2, wherein the receiving hole of the tube rack
includes, in
successive order from a top of the receiving hole toward a bottom of the
receiving hole, a
large diameter section, a shoulder, and a small diameter section, wherein the
shoulder of
the receiving hole is adapted to stop a shoulder of the test tube.
4. The device of claim 2, wherein the tube rack has a bottom end inserted
into the
passage of the heat dissipation base.
5. The device of any one of claims 1 to 4, wherein the small diameter
section of the
passage of the heat dissipation base has a gradually decreasing diameter from
the top to
the bottom of said passage of said heat dissipation base.
6. The device of claim 1, wherein the heat dissipation base is made of
metal.
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Description

CA 02856345 2017-01-09
DEVICE FOR THERMAL CONVECTION POLYMERASE CHAIN
REACTION
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to devices for use in polymerase
chain reaction (hereinafter referred to as "PCR") and more particularly, to a
device for
holding a test tube for insulated isothermal PCR.
2. Description of the Related Art
In the field of biotechnology, polymerase chain reaction (PCR) is a
well-known technology used to amplify specific nucleic acid sequences. The PCR

process comprises three major steps including denaturation, primer annealing
and
extension. which require different reaction temperatures. The required
temperature for
the denaturation step is typically in a range between 90 C and 97 C. The
required
temperature for the primer annealing step will depend on the melting
temperature of
the primer used. Typically, the annealing temperature ranges from 35 C to 65
C. The
required temperature for the extension step is typically about 72 C.
The insulated isothermal PCR is based on Rayleigh-Benard convection,
which is driven by buoyancy when heating fluid layer from below, is a common
physical phenomenon. The insulated isothermal PCR is generally performed by
immersing the bottom of a test tube which contains a mixed liquid into a hot
water in
such a way that the rest of the test tube is exposed to atmosphere at room
temperature
for heat dissipation. As a result, the temperature of the mixed liquid will
gradually
decrease from the bottom of the mixed liquid having a temperature of about 97
C
toward the surface of the mixed liquid having a temperature of about 35 C.

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=
Because of the temperature gradient, the heat convection is induced, such that
the
mixed liquid will flow through various regions having different temperatures
and then
undergo different reaction steps.
In the conventional device for performing a convection PCR, because the
portion of the test tube, which is exposed to the ambient air at room
temperature for
heat dissipation, has a low heat dissipating rate, the temperature at the
surface of the
mixed liquid will become higher and higher due to the increment of the heating
time.
As a result, the temperature at the surface of the mixed liquid may rise to a
degree
higher than the required temperature suitable for conducting the primer
annealing step
before the convection PCR has been performed completely. Under this
circumstance,
the polymerase chain reaction may break, such that a desired, large amount of
copies
of specific nucleic acid sequences may not be obtained.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above-noted
circumstances. It is the primary objective of the present invention to provide
a device
for insulated isothermal PCR, which can ensure that the temperature at the
surface of
the mixed liquid is lower than the temperature suitable for conducting the
primer
annealing step in the PCR process.
To achieve the above-mentioned objective, the device provided by the
present invention is adapted for holding a test tube in which an insulated
isothermal
polymerase chain reaction is performed, which comprises a heat radiating base
having
a body provided with a passage for insertion of the test tube. The passage has
a large
diameter section and a small diameter section located below the large diameter
section.
By means of the design of the present invention, the temperature at the
surface of the
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CA 02856345 2017-01-09
mixed liquid can be kept in a degree lower than the temperature suitable for
conducting
the primer annealing step in the PCR process.
According to one aspect of the invention, it is provided that a device for
holding a
test tube in which insulated isotheimal polymerase chain reaction is
performed, the
= device comprising: a heat radiating base having a body provided with a
passage for
insertion of the test tube, wherein the passage has a large diameter section
and a small
diameter section located below the large diameter section; wherein the heat
radiating base
dissipates heat from the test tube which is inserted in the passage; the heat
radiating base
leaves a bottom of the test tube exposed outside to be heated.
According to another aspect of the present invention, there is provided a
device
for holding a test tube in which thelinal convection polymerase chain reaction
is
performed, and for dissipating heat from the test tube, the device comprising:

a heat dissipation base having a body provided with a passage for insertion of
the
test tube, wherein the passage has a large diameter section and a small
diameter section
located below the large diameter section;
wherein the test tube and the heat dissipation base are separated by an air
space; the
heat dissipation base dissipates heat from the test tube which is inserted in
the passage;
the heat dissipation base leaves a bottom of the test tube exposed outside to
be heated.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed
description given herein below and the accompanying drawings which are given
by way
of illustration only, and thus are not limitative of the present invention,
and wherein:
FIG. 1 is a schematic drawing showing a device for insulated isothermal PCR
according to a preferred embodiment of the present invention; and
FIG. 2 is an exploded view of the device for insulated isothermal PCR of the
preferred embodiment of the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, a device 10 for insulated isothermal PCR mainly comprises
a
heat radiating base 20 and a tube rack 30. The heat radiating base 20 includes
a body 22
provided with a passage 24 for insertion of a test tube 12. The passage 24 has
a large
diameter section 241 and a small diameter section 242 located below the large
diameter
section 241. Because a middle section 123 and an upper section 122 of the test
tube 12
are located inside the passage 24 of the heat radiating base 20 and the heat
radiating base
20 is made of a material having a high heat transfer coefficient, such as
aluminum, the
heat energy of the mixed liquid of PCR will be transferred through the ambient
atmosphere to the heat radiating base 20 for heat dissipation efficiently,
such that during
the PCR process the temperature at the surface of the mixed liquid can be
maintained at a
degree of about 10-55 C, which is lower
20
30
3a

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than the temperature suitable for performing the primer annealing step,
thereby
preventing the PCR from being interrupted due to high temperature at the mixed
liquid
level. In addition, the heat dissipation of the mixed liquid at the region
corresponding
to the large diameter section 241 will be lower than that at the region
corresponding to
the small diameter section 242. It is revealed by experiments that the
configuration of
the heat radiating base 20 provided by the present invention has a heat-
dissipating
effect helpful for conducting the insulated isothermal PCR.
In order to stably mount the test tube 12 in the heat radiating base 20, the
tube rack 30 can be further provided on the heat radiating base 20. The tube
rack 30 is
provided with a receiving hole 32 for insertion of the test tube 12 to stably
position the
test tube 12, thereby preventing the outer wall surface of the test tube 12
from
contacting the wall surface of the passage 24 of the heat radiating base 20 so
as to
avoid that the temperature of the mixed liquid drops too quickly.
In practice, the receiving hole 32 of the tube rack 30 may be configured, in
succession order from a top thereof toward a bottom thereof, a large diameter
section
321, a shoulder 322 and a small diameter section 323. in which the shoulder
322 is
adapted for stopping a shoulder 121 of the test tube 12 such that the test
tube 12 can be
stably positioned. In addition, a support seat 40 is provided below the heat
radiating
base 20. The bottom 124 of the test tube 12 is heated by a heat source (not
shown in
the drawings) to keep the temperature of the mixed liquid of PCR inside the
bottom
124 in a range about 90 C to 97 C.
Further, the bottom end 301 of the tube rack 30 is inserted into the passage
24 of the heat radiating base 20, such that the tube rack 30 is stably mounted
on the
heat radiating base 20.
Furthermore, in the preferred embodiment of the present invention, the
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diameter of the small diameter section 242 of the passage 24 is configured to
gradually
and downwardly decrease. According to many experiments and modifications, it
is
found that using this configuration to dissipate heat can yield a highest
reaction
efficiency of PCR. The aforesaid experiments for PCR were conducted in seven
different environmental temperatures ranging from 10 C to 40 C with a
condition that
the mixed liquid inside the bottom 124 of the test tube 12 was heated to 93 C
to 97 C.
The temperature of the heat radiating base 20 measured ranges from 36 C to 53
C, and
the temperature at the mixed liquid level measured ranges from 36 C to 53 C;
therefore, the PCR is performed smoothly.
The invention being thus described, it will be obvious that the same may be
varied in many ways. For example, as shown in FIG. 2, the heat radiating base
20 can
be provided with a plurality of passages 24 for holding a plurality of test
tubes 12 for
simultaneously performing polymerase chain reactions. Such variations are not
to be
regarded as a departure from the spirit and scope of the invention, and all
such
modifications as would be obvious to one skilled in the art are intended to be
included
within the scope of the following claims.
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Representative Drawing