1520-Plat

Binding kinetics in a laminar flow mixing device: modeling and experimental verification.

Warren Zipfel¹, Jonas Korlach¹, Lisa Kwok¹, Rebecca Williams¹, Watt Webb¹, Lois Pollack¹

1Cornell University, Applied and Engineering Physics, 212 Clark Hall, Ithaca, New York 14853

We describe the use and analysis of a laminar flow or diffusional mixing device first described by Knight et al. (Phys. Rev. Lett. 80:3863). Rate constants of second order reactions can be obtained by assuming simple lateral diffusion of the reactant species into the center jet and application of the appropriate kinetic model. Required operational parameters such as flow velocity were determined using fluorescence correlation spectroscopy, and the dynamics of mixing and binding was acquired by multiphoton fluorescence imaging of the jet. Verification of the model is demonstrated by measurements of calcium binding to indicator dyes yielding nearly diffusion-limited second order rate constants for calcium binding equivalent to those determined by other methods. The working model is useful for understanding the device limitations for kinetics measurements and for obtaining useful specifications for the design of improved laminar flow mixers. This research was made possible in part by grant number P41-RR04224 to WRZ, JK, RMW and WWW from the National Center for Research Resources, National Institutes of Health.