(83c) Surface Modification of Polymeric Substrate: Chemical, Topographical and Mechanical Cues Influencing Stem Cell Behavior

In cell culture, substrate surfaces are usually modified in a ?subtractive? or ?additive? manner to favor cell adhesion. Chemical etching and peptide conjugation of the substrate surface are examples of these two manners, respectively. It has been known that the surface modification may change its chemistry and topography. Here, we show that surface modification of polydimethylsiloxane (PDMS) using oxygen plasma changed the surface chemistry, and consequently the topography and elasticity of PDMS. PDMS has been widely used as a substrate for cell culture in biochips and microfluidics. However, the hydrophobic nature of the surface is a limitation. The most common practice is to utilize oxygen plasma to treat the PDMS and render a hydrophilic surface for improving cell adhesion. We investigated the oxygen plasma treatment of PDMS in terms of wettability, chemistry, topography and mechanical properties, detailed the plasma treatment process, and clarified the recovery mechanism. It was discovered that the oxygen plasma-induced chemical change modified the topography and the Young's modulus of PDMS. The latter factor has the predominant effect, overriding the chemical and topographical factors, on adhesion and differentiation of human mesenchymal stem cells (hMSCs) directly seeded on the PDMS surface. The collagen coating weakened the influence of stiffness change on the behaviors of hMSCs.