Electrically conducting polymer reaction vessels

Details Electrically conducting polymer reaction vessels Electrically conducting polymer reaction vessels

1999-06-25

2002-08-20

Tran, Hien (Department: 1764)

Chemical apparatus and process disinfecting, deodorizing, preser

Chemical reactor

Including heat exchanger for reaction chamber or reactants...

C422S109000, C422S198000

Reexamination Certificate

active

06436355

ABSTRACT:

The present invention relates to vessels and apparatus for controlled heating of reagents for example those used in biochemical reactions and to methods for using these.
The controlled heating of reaction vessels is often carried out using solid block heaters which are heated and cooled by various methods. Current solid block heaters are heated by electrical elements or thermoelectric devices inter alia. Other reaction vessels may be heated by halogen bulb/turbulent air arrangements. The vessels may be cooled by thermoelectric devices, compressor refrigerator technologies, forced air or cooling fluids. The reaction vessels fit into the block heater with a variety of levels of snugness. Thus, the thermal contact between the block heater and the reaction vessel varies from one design of heater to another. In reactions requiring multiple temperature stages, the temperature of the block heater can be adjusted using a programmable controller for example to allow thermal cycling to be carried out using the heaters.
This type of heater arrangement is particularly useful for reactions requiring thermal cycling, such as DNA amplification methods like the Polymerase Chain Reaction (PCR). PCR is a procedure for generating large quantities of a particular DNA sequence and is based upon DNA's characteristics of base pairing and precise copying of complementary DNA strands. Typical PCR involves a cycling process of three basic steps.
Denaturation: A mixture containing the PCR reagents (including the DNA to be copied, the individual nucleotide bases (A,T,G,C), suitable primers and polymerase enzyme) are heated to a predetermined temperature to separate the two strands of the target DNA.
Annealing: The mixture is then cooled to another predetermined temperature and the primers locate their complementary sequences on the DNA strands and bind to them.
Extension: The mixture is heated again to a further predetermined temperature. The polymerase enzyme (acting as a catalyst) joins the individual nucleotide bases to the end of the primer to form a new strand of DNA which is complementary to the sequence of the target DNA, the two strands being bound together.
A disadvantage of the known block heaters arises from the lag time required to allow the heating block to heat and cool to the temperatures required by the reaction. Thus, the time to complete each reaction cycle is partially determined by the thermal dynamics of the heater in addition to the rate of the reaction. For reactions involving numerous cycles and multiple temperature stages, this lag time significantly affects the time taken to complete the reaction. Thermal cyclers based on such block heaters typically take around 2 hours to complete 30 reaction cycles.
For many applications of the PCR technique it is desirable to complete the sequence of cycles in the minimum possible time. In particular for example where respiratory air or fluids or foods for human and animal stock consumption are suspected of contamination rapid diagnostic methods may save considerable money if not health, even lives.
An alternative thermal cycler contains a number of capillary reaction tubes which are suspended in air. The heating and cooling of the reaction tubes is effected using a halogen lamp and turbulent air from a fan. The thermal dynamics of this system represent a considerable improvement over the traditional block heater design because heated and cooled air is passed across the reaction tubes and the required temperatures are achieved quite rapidly, the fan providing a homogeneous thermal environment and forced cooling. Using this apparatus 30 reaction cycles can be completed in about 15 minutes.
A disadvantage of this thermal cycler is that air cooling and heating are not readily suitable in multi-shot apparatus, certainly not, mobile or portable such apparatus.
The applicants have developed an efficient system for rapid heating and cooling of reactants which is particularly useful in thermal cycling reactions.
Accordingly, the present invention provides a reaction vessel comprising an electrically conducting polymer which emits heat when an electric current is passed through it.
Electrically conducting polymers are known in the art and may be obtained from Caliente Systems Inc. of Newark, USA. Other examples of such polymers are disclosed for instance in U.S. Pat. Nos. 5,106,540 and 5,106,538. Suitable conducting polymers can provide temperatures up to 300° C. and so are well able to be used in PCR processes where the typical range of temperatures is between 30° and 100° C.
An advantage of the invention over a conventional block heater is derived from the fact that polymers which conduct electricity are able to heat rapidly. The heating rate depends upon the precise nature of the polymer, the dimensions of polymer used and the amount of current applied. Preferably the polymer has a high resistivity for example in excess of 1000 ohm·cm. The temperature of the polymer can be readily controlled by controlling the amount of electric current passing through the polymer, allowing it to be held at a desired temperature for the desired amount of time. Furthermore, the rate of transition between temperatures can be readily controlled after calibration, by delivering an appropriate electrical current, for example under the control of a computer programme.
Furthermore as compared to a block heater, rapid cooling can also be assured because of the low thermal mass of the polymer. If desired however, the reaction vessel may be subjected to artificial cooling to further increase the speed of cooling.
Suitable cooling methods include forced air cooling, for example by use of fans, immersion in ice or water baths etc.
In addition, the use of polymer as the heating element in a reaction vessel will generally allow the apparatus to take a more compact form than existing block heaters, which is useful when carrying out chemical reactions in field conditions such as in the open air, on a river, on a factory floor or even in a small shop.
The reaction vessel may take the form of a reagent container such as a glass, plastics or silicon container, with electrically conducting polymer arranged in close proximity to the container. In one embodiment of the vessel, the polymer is provided as a sheath which fits around the reaction vessel, in thermal contact with the vessel. The sheath can either be provided as a shaped cover which is designed to fit snugly around a reaction vessel or it can be provided as a strip of film which can be wrapped around the reaction vessel and secured.
The polymer sheath arrangement means that close thermal contact is achievable between the sheath and the reaction vessel. This ensures that the vessel quickly reaches the desired temperature without the usual lag time arising from the insulating effect of the air layer between the reaction vessel and the heater. Furthermore, a polymer sheath can be used to adapt apparatus using pre-existing reaction vessels. In particular, a strip of flexible polymer film can be wrapped around a reaction vessel of various different sizes and shapes.
Where a sheath is employed it may be advantageous for it to be perforated or in some way reticulated. This may increase the flexibility of the polymer and can permit even readier access by a cooling medium if the polymer is not itself used to effect the cooling.
In another embodiment of the invention, the polymer is provided as an integral part of the reaction vessel. The reaction vessel may be made from the polymer by extrusion, injection moulding or similar techniques. Alternatively, the reaction vessel may be manufactured using a composite construction in which a layer of the conducting polymer is interposed between layers of the material from which the vessel is made or in which the internal or external surfaces of the reaction vessel is coated with the polymer, or again in which the vessel is basically made of the polymer coated with a thin laminate of a PCR compatible material. Such vessels may be produced using lamination and/or deposition such as chemical

Affiliated with

Also associated with

Rating

Electrically conducting polymer reaction vessels does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electrically conducting polymer reaction vessels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrically conducting polymer reaction vessels will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2954258