Combination Of Physical And Chemical Modification On The Surface Of PDMS

Because of its easy fabrication, non-toxicity, good elasticity, high chemical resistance and optical transparency, polydimethylsiloxane (PDMS) is widely used in microfluidic-based analytical chemistry and bio-analytical chemistry applications in the past decades. In spite of the many advantages of PDMS, however, the surface of PDMS is naturally hydrophobic, which limits its practice in a variety of applications. Consequently, a lot of efforts have been made to modify PDMS to enhance its surface property.Well defined nanostructures were created on PDMS surface through anodized aluminum oxide (AAO) template method. On top of the nanostructures, polyvinyl alcohol (PVA) was coated after the nano patterned PDMS was exposed to air plasma. The influence of the combined modification on surface properties of PDMS was examined by ATR-FTIR and water contact angle measurement. The impact of plasma pretreatment time and storage time in ambient environment were investigated, and property of films with or without nanostructures was compared. Experimental results show that long-term stable hydrophilic surfaces of PDMS can be achieved by PVA coating and be further improved by the surface nanostructures. The modified PDMS was also used for cell culture. The results indicate that both nano structuring and chemically modifying the PDMS surface improves cell growth. Additionally. combination of these surface modifications has an additive effect on cell proliferation.Hyaluronic acid (HA) is widely presented in the extracellular matrix. It is a linear polysaccharide composed by repeat N-acetyl glucosamine and D-glucuronic acid. CD44is a class of transmembrane glycoprotein and is the most important hyaluronan receptor on the cell surface. It is expected to find an efficient and simple way to capture cancer cells using the affinity between HA and CD44. In the experiment, HA was modified on the nano structured PDMS. The modified PDMS could promote cell growth and the effect become greater with time. By integration of HA modification into microfluidic channel, cell capture could be achieved.The nanostructures on the surface of PDMS could improve the enrichment of small molecule drugs, such as quinine and ciprofloxacint. The fluorescence signal was significantly enhanced by nano structureed PDMS compared with native PDMS. This method can provide a simple and convenient analytical tool for drug screening.In the future, it is planned to modify the surface of PDMS with more specific substances such as antigen-antibody in order to improve the combination efficiency and selectivity. This specific modification can provide a new way for cell enrichment and screening.