Convenient Method for Modifying Poly(dimethylsiloxane) with Poly(ethylene glycol) in Microfluidics

This report describes a convenient and reproducible method for the covalent modification of poly(dimethylsiloxane) (PDMS) with poly(ethylene glycol) (PEG) chains to suppress nonspecific protein adsorption. PEG additives terminated with a vinyl group are added into the PDMS prepolymer; when the PDMS is thermally cured, the vinyl group reacts with the silane groups on the PDMS, which covalently link the PEG group to the PDMS network. The PEG-modified PDMS surfaces are characterized with FT-IR, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. We also examined the modified PDMS for on-chip capillary electrophoresis and its capability of resisting nonspecific protein adsorption using bovine serum albumin (BSA) as a model. Based on our study, a molecular mechanism is given to successfully explain the surface properties of the modified PDMS surfaces.