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Millisecond kinetics on a microfluidic chip using nanoliters of reagents

Song, Helen and Ismagilov, Rustem F. (2003) Millisecond kinetics on a microfluidic chip using nanoliters of reagents. Journal of the American Chemical Society, 125 (47). pp. 14613-14619. ISSN 0002-7863. doi:10.1021/ja0354566.

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This paper describes a microfluidic chip for performing kinetic measurements with better than millisecond resolution. Rapid kinetic measurements in microfluidic systems are complicated by two problems: mixing is slow and dispersion is large. These problems also complicate biochemical assays performed in microfluidic chips. We have recently shown (Song, H.; Tice, J. D.; Ismagilov, R. F. Angew. Chem., Int. Ed. 2003, 42, 768-772) how multiphase fluid flow in microchannels can be used to address both problems by transporting the reagents inside aqueous droplets (plugs) surrounded by an immiscible fluid. Here, this droplet-based microfluidic system was used to extract kinetic parameters of an enzymatic reaction. Rapid single-turnover kinetics of ribonuclease A (RNase A) was measured with better than millisecond resolution using sub-microliter volumes of solutions. To obtain the single-turnover rate constant (k = 1100 +/- 250 s(-1)), four new features for this microfluidics platform were demonstrated: (i) rapid on-chip dilution, (ii) multiple time range access, (iii) biocompatibility with RNase A, and (iv) explicit treatment of mixing for improving time resolution of the system. These features are discussed using kinetics of RNase A. From fluorescent images integrated for 2-4 s, each kinetic profile can be obtained using less than 150 nL of solutions of reagents because this system relies on chaotic advection inside moving droplets rather than on turbulence to achieve rapid mixing. Fabrication of these devices in PDMS is straightforward and no specialized equipment, except for a standard microscope with a CCD camera, is needed to run the experiments. This microfluidic platform could serve as an inexpensive and economical complement to stopped-flow methods for a broad range of time-resolved experiments and assays in chemistry and biochemistry.

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URLURL TypeDescription CentralArticle
Ismagilov, Rustem F.0000-0002-3680-4399
Additional Information:Copyright © 2003 American Chemical Society. Published In Issue: November 26, 2003. Received April 4, 2003. This work was supported by the NIH (R01 EB001903), the Beckman Young Investigator program, Searle Scholars Program, the Predoctoral Training Grant (H.S.) of the NIH (GM 08720), and the Camille and Henry Dreyfus New Faculty Award. At The University of Chicago, work was performed at the MRSEC microfluidic facility funded by the NSF and at the Cancer Center DLMF. Photolithography was performed at MAL of the UIC. We thank A.V. Korennykh and Prof. J. A. Piccirilli for helpful suggestions and for providing samples of RNase A, Prof. T. R. Sosnick and Prof. T. Pan for helpful discussions, and J.D. Tice for the image shown in Figure 1 and for invaluable experimental assistance.
Funding AgencyGrant Number
NIBIBR01 EB001903
Beckman Young Investigator awardUNSPECIFIED
Searle Scholars ProgramUNSPECIFIED
NIHGM 08720
Camille and Henry Dreyfus FoundationUNSPECIFIED
Subject Keywords:x-ray-scattering; ribonuclease-a; time; flow; microreactor; substrate; enzyme; assay; base; step
Issue or Number:47
Record Number:CaltechAUTHORS:20130821-160732315
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40872
Deposited By: Whitney Barlow
Deposited On:28 Aug 2013 21:21
Last Modified:10 Nov 2021 04:23

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