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Published January 15, 1998 | public
Journal Article

Microfabricated Silicon Mixers for Submillisecond Quench-Flow Analysis


Elucidation of fast chemical reactions such as protein folding requires resolution on a submillisecond time scale. However, most quench-flow and stop-flow techniques only allow chemical processes to be studied after a few milliseconds have elapsed. In order to shorten the minimum observation time for quench-flow experiments, we designed a miniaturized mixer assembly. Two "T" mixers connected by a channel are etched into a 1 cm × 1 cm silicon chip which is interfaced with a commercially available quench-flow instrument. Decreasing the volume of the mixing chambers and the distance between them results in an instrument with greatly reduced dead times. As a test of submillisecond measurements, we studied the basic hydrolysis of phenyl chloroacetate. This reaction proceeds with a second-order rate constant, k = 430 M^(-1) s^(-1), and shows pseudo-first-order kinetics at high hydroxide concentrations. The chemical reaction data demonstrate that the silicon device is capable of initiating and quenching chemical reactions in time intervals as short as 110 μs. The performance of these mixers was further confirmed by visualization using acid-base indicators.

Additional Information

© 1998 American Chemical Society. Received for review July 30, 1997. Accepted October 22, 1997. Publication Date (Web): January 15, 1998. Abstract published in Advance ACS Abstracts, December 15, 1997. This work was supported by the Rita Allen Foundation, the David and Lucile Packard Foundation and the Searle Scholars Program/The Chicago Community Trust. D.B. acknowledges support from the Deutsche Forschungsgemeinschaft.

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