Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
2000-11-20
2003-10-21
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S325000, C435S243000, C435S304100, C435S305200, C219S386000, C219S428000, C219S438000
Reexamination Certificate
active
06635471
ABSTRACT:
The present invention relates to the use of electrically conducting polymers in the production of apparatus such as incubators for use in the culture of biological material as well as apparatus and methods for incubating biological material.
Culture of biological material, such as plant or animal cells, bacteria, viruses or hybridoma or other immortal cell lines are required in a wide variety of purposes. For example, the cell lines may be cultured for use in experimental purposes. In addition, bacteria and in particular recombinant bacteria may be cultured used in the production of materials such as antibiotics or other pharmaceuticals. Antibodies useful in diagnosis and therapy in a wide range of fields are prepared for example by the culture of hybridoma or other immortal cells lines.
For diagnostic purposes, for example in the areas of food hygiene monitoring, it may be necessary to culture any bacterial or viral strains isolated in order to obtain significant quantities for detection and/or identification.
Plant cells may be cultured to prepare calluses for use in transformation to produce recombinant plants.
The controlled heating of shake flasks or other vessels used in the culture of biological material is often carried out using large heaters or incubators. Multiple shake flasks, each containing the biological material to be tested and culture medium are held within these devices. The temperature within the incubator is held at a temperature at which the biological material may be grown. Generally, this will be of the order of 37° C. which is an acceptable temperature for the culture of many types of biological material. However, this may not be the optimum culture temperature for all biological material being cultured within the container, particularly when a wide range of different biological materials are contained within different individual shake flasks.
Furthermore, this may not provide an economical method of heating where only a small number of samples are required as it is necessary to heat and maintain the entire apparatus at the desired temperature, even when only a few samples are contained within it.
Finally, incubation of certain strains, in particular recombinant stains of bacteria etc. require specific temperature conditions and transitions in order to induce or “switch on ” desired genes. Certain strains require culturing for a predetermined period at one temperature followed by adjustment of the temperature to a different level in order to obtain expression of a particular gene. At present, such a complex operation has to be carried out manually, which means that an operator has to be present at the particular moment when the temperature change is required, in order to remove the incubation vessel from the constant temperature environment, and heat or cool it as appropriate.
There is a need for a more controllable method of heating incubation vessels used in the culture of biological material. Copending International Patent Application No. PCT/GB97/03187 describes reaction vessels which utilise electrically conducting polymers as the heating means. It has been found that such vessels may be adapted for use in the incubation of biological material.
According to the present invention there is provided the use of incubation means for the controlled heating of biological materials, said means comprising an electrically conducting polymer connectable to a power supply, said polymer being either contiguous or integral with an incubation vessel, or adapted to be in thermal contact with an incubation vessel.
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. No. 5,106,540 and U.S. Pat. No. 5,106,538. Many polymers, for example, polytetrafluoroethylene (PTFE) or polyethylene (PE) can be formed into electrically conducting polymers by inclusion of graphite in the polymer material.
Suitable conducting polymers can provide temperatures up to 300° C. and so are well able to be used in incubation processes where the range of temperatures is between 0° and 100° C., typically between 15° and 50° C.
Incubation vessels which may be used in the context of the invention are well known in the art. They may comprise shake flasks, petrie dishes, test tubes, chemostats, fermenters or slides including microscope slides.
An advantage of the invention over a known incubators or ovens is that the temperature within individual incubation vessels can be controlled independently of one another.
The heating rate achievable 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.
Suitably however, the temperature within each vessel may be set using for example a simple thermostat device which cuts off the current to the polymer if the temperature within the flask exceeds the desired temperature.
The thermal properties of an electrically conducting polymer and in particular it low thermal mass, will ensure that adjustments in the temperature will take place rapidly. If desired however, the incubation 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 an incubation vessel will generally allow the apparatus to take a more compact form than existing incubators. This may be useful when carrying out culture processes in field conditions such as in the open air, on a river, on a factory floor or even in a small shop.
The incubation 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 incubation vessel, in thermal contact with the vessel. The sheath can either be provided as a shaped cover which is designed to fit snugly around an incubation vessel or it can be provided as a strip of film which can be wrapped around the incubation vessel and secured.
The polymer sheath arrangement means that close thermal contact is achievable between the sheath and the incubation 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 incubation vessel and the heater. Furthermore, a polymer sheath can be used to adapt apparatus using pre-existing incubation vessels. In particular, a strip of flexible polymer film can be wrapped around an incubation 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 incubation vessel. The incubation vessel may be made from the polymer by extrusion, injection moulding or similar techniques. Alternatively, the incubation 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 incubation vessel is coated with the polymer, or again in which the vesse
Lee Martin A
Leslie Dario L
Moore Paul
Beisner William H.
Nixon & Vanderhye P.C.
The Secretary of State for Defence in Her Britannic Majesty&apos
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