Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane)

SDS capillary gel electrophoresis of proteins in microfabricated channels

Analysis of variations in the concentrations or structures of biomolecules (e.g., mRNAs, proteins, peptides, natural products) that occur either naturally or in response to environmental or genetic perturbations can provide important insight into complex biological processes. Many biological samples are mixtures that require a separation step before quantitation of variations in the individual components. Two-dimensional denaturing gel electrophoresis has been used very effectively to separate complex mixtures of proteins, but it is time consuming and requires considerable amounts of sample. Microchannel-based separations have proven very effective in rapidly separating small amounts of nucleic acids; more recently, isoelectric focusing of proteins also has been adapted to the microchannel format. Here, we describe microchannel-based SDS capillary gel electrophoresis of proteins and demonstrate the speed and high resolution it provides. This development is an important step toward the miniaturization and integration of multidimensional and array separation methods for complex protein mixtures.

Patterning cells and their environments using multiple laminar fluid flows in capillary networks

This paper describes the use of laminar flow of liquids in capillary systems to pattern the cell culture substrate, to perform patterned cell deposition, and to pattern the cell culture media. We demonstrate the patterning of the cell culture substrate with different proteins, the patterning of different types of cells adjacent to each other, the patterned delivery of chemicals to adhered cells, and performing enzymatic reactions over select cells or over a portion of a cell. This method offers a way to simultaneously control the characteristics of the surface to which cells are attached, the type of cells that are in their vicinity, and the kind of media that cells or part of a cell are exposed to. The method is experimentally simple, highly adaptable, and requires no special equipment except for an elastomeric relief that can be readily prepared by rapid prototyping.