title: Rapid generation of spatially and temporally controllable long-range concentration gradients in a microfluidic device.
abstract: The ability to rapidly generate concentration gradients of diffusible molecules has important applications in many chemical and biological studies. Here we established spatially and temporally controllable concentration gradients of molecules (i.e. proteins or toxins) in a portable microfluidic device in an easy and rapid manner. The formation of the concentration gradients was initiated by a passive-pump-induced forward flow and further optimized during an evaporation-induced backward flow. The centimeter-long gradients along the microfluidic channel were shown to be spatially and temporally controlled by the backward flow. The gradient profile was stabilized by stopping the flow. Computational simulations of this dynamic process illustrated the combined effects of convection and diffusion on the gradient generation, and fit well with the experimental data. To demonstrate the applications of this methodology, a stabilized concentration gradient of a cardiac toxin, alpha-cypermethrin, along the microchannel was used to test the response of HL-1 cardiac cells in the micro-device, which correlated with toxicity data obtained from multi-well plates. The approach presented here may be useful for many biological and chemical processes that require rapid generation of long-range gradients in a portable microfluidic device.
authors.affiliation: Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Du
authors.forename: Jaesool
authors.initials: J
authors.lastname: Shim
authors.forename: Mahesh
authors.initials: M
authors.lastname: Vidula
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hancock
authors.forename: Edward
authors.initials: E
authors.lastname: Lo
authors.forename: Bong Geun
authors.initials: BG
authors.lastname: Chung
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Borenstein
authors.forename: Masoud
authors.initials: M
authors.lastname: Khabiry
authors.forename: Donald M
authors.initials: DM
authors.lastname: Cropek
authors.forename: Ali
authors.initials: A
authors.lastname: Khademhosseini
mesh_terms: D000818:Animals; D002460:Cell Line; D003198:Computer Simulation; D004058:Diffusion; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D009206:Myocardium / Q000166:cytology; D013997:Time Factors