Preparation and Surface PEGylation of Crosslinked Polydimethylsiloxane Substrates with Tunable Moduli
Mechanical patterns on cell culture substrates can be potentially used as effective cues in directing cell migrations. Fully functional substrates require not only readily tunable modulus to generate mechanical stimuli but also proper surface properties to ensure proper interactions with the surrounding media. In this study, crosslinked polydimethylsiloxane (PDMS) with tunable modulus ranging from 50 to 1000 kPa was fabricated using platinum-catalyzed hydrosilylation between vinyl and -SiH functionalized PDMS pre-polymers. Substrate modulus was tuned as a function of the density of the reactive moieties (-SiH) on crosslinkers, the molar ratio between vinyl and -SiH functionalities, and the average molecular weight between adjacent crosslinkers. To overcome the hydrophobicity of PDMS surfaces, mono-vinyl-terminated polyethylene glycol (V-PEG) was grafted onto crosslinked PDMS thin films containing excess -SiH functionality via surface hydrosilylation reaction. Efficiency of surface PEGylation was controlled by surface density of -SiH groups, molecular weight of V-PEG, and catalyst concentrations.