Miniaturized flow thermocycler

Details Miniaturized flow thermocycler Miniaturized flow thermocycler

1996-05-23

1998-02-10

Redding, David A.

Chemistry: molecular biology and microbiology

Apparatus

4352891, 4352931, 422 681, 422 8211, 422102, 422109, 422198, C12M 300

Patent

active

057168423

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a miniaturized flow thermocycler applicable in thermally controlled biochemical and biological molecular processes, respectively, particularly for use in so-called polymerase chain reaction methods in which definite sequences out of a mixture of DNA sequences are amplified.
When carrying out thermally controlled biochemical and biological molecular processes, respectively, very often procedure steps at different temperatures are required. Such an exposure to varying temperatures is of particular importance in the so-called polymerase chain reaction.
The polymerase chain reaction method has been recently developed to amplify definite DNA sequences and its essential features have been outlined in "Molekulare Zellbiologie", Walter de Gruyter, Berlin-New York 1994, pg. 256/257' by Damell, J.; Lodish, H.; Baltimore, D. Inter alia, it is essential in the method that mixtures of DNA sequences are subject to definitely varying temperatures. To this end stationary sample treatment devices are employed where the respective samples are inserted into reaction chambers for being subject to a periodical hot-cold-temperature cycle, the respectively desired DNA sequences being amplified depending on the specifically preselected primers. The efficiency of the reaction chambers known heretofore is considered insufficient. Therefore a miniaturized reaction chamber has recently been proposed (Northrup et al, DNA Amplification with Microfabricated reaction chamber, 7th International Conference on Solid State Sensors and Actuators, Proc. Transducers 1993, pg. 924-26), which permits a four-times faster amplification of desired DNA sequences compared to known arrangements. The reaction chamber which is capable to of receiving up to 50 .mu.reaction fluid comprises a structurized silicon cell of a longitudinal extension on an order of size of 10 mm which is, in one sample injection direction, sealed by a thin diaphragm via which the temperature exposure is executed by miniaturized heating elements. Also with this device the DNA sequence to be amplified is inserted via micro-channels into the cell, subjected to a polymerase chain reaction and subsequently drawn off. Irrespective of the advantages obtained with the device, it still exhibits the disadvantage that the reaction chamber has to be heated and cooled in its entity which only permits limited rates of temperature changes. Particularly at a further reduction of the sample sizes, the parasitic heat capacity of the reaction chamber and, if employed, of a tempering block becomes more dominant to the reaction liquid so that the high temperature changing rates, otherwise feasible with small liquid volumes, cannot be achieved, which renders the efficiency of the method comparatively low. Additionally, a comparatively expensive control system is required to obtain a respectively stable temperature control of the reaction liquid furthermore, the heating and cooling power applied, respectively, is substantially consumed in the ambient units rather than in the reaction liquid.
Furthermore, a thermocycler operating on the flow principle is known from the U.S. Pat. No. 5,270,183 in which the reaction liquid to be amplified passes through a tube being subsequently wound once or multifold around a plurality of cylinders which are kept on different temperatures. As it is, such an arrangements permits amplification of even comparatively low sample amounts down to 25 .mu.l. However, such a device is very difficult to handle and requires considerable skill on the side of the apparatus producer so that it is entirely unsuited for large scale production.


SUMMARY OF THE INVENTION

It is an object of the present invention provide a miniaturized thermocycler which, compared to the state of art, permits to more effective control of biochemical and biological molecular, respectively, processes and, in particular, the method for polymerase chain reaction, which obviates the problem of parasitic heat capacities and which is inexpensive in manufactu

REFERENCES:
patent: 5270183 (1993-12-01), Corbett et al.
patent: 5498392 (1996-03-01), Wilding et al.
patent: 5587128 (1996-12-01), Wilding et al.
"Molekulare Zellbiologie", (by Darnell, J.; Lodish, H.; Baltimore, D., published by Walter de Gruyter, Berlin-New York 1994, pp. 256-257).
"DNA Amplification With A Microfabricated Reaction Chamber", (by M. Allen Northrup, Michael T. Ching, Richard M. White, and Robert T. Watson, 7th International Conference on Solid State Sensors and Actuators, Proc. Transducers 1993, pp. 924-926).

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