Surface forces affecting the biocompatibility of modified polydimethylsiloxane films

This study investigates the changes in surface properties once polysaccharides and polyethylene glycol are covalently bonded to the surface of polydimethylsiloxane with the goal of understanding how changes in those properties would affect the surface forces relevant to protein adsorption. Polydimethylsiloxane (PDMS) was selected as a substrate for its use in microfluidic and biomedical applications. PDMS is treated with a remote microwave oxygen plasma to form hydroxyl groups which allow for grafting sites for covalent attachment. The effects of chamber pressure and substrate temperature on the hydroxyl group formation rate are measured and optimized. The PDMS and modified PDMS films are characterized by contact angle, zeta potential, tapping mode atomic force microscopy (AFM) imaging, and Hamaker constants with model hydrophobic and hydrophilic particles. The relative effects on the van der Waals and electrostatic forces are discussed.