Surface Modification Of Poly (Dimethylsiloxane) By Polysaccharides And Assay Of Their Biocompatibility

An improved approach for the surface modification of poly(dimethylsiloxane) (PDMS) using carboxymethylcellulose (CMC), carboxymethyl-β-1,3-dextran (CMD), and alginic acid (AA) was investigated. The PDMS substrates were first oxidized in an H2SO4/H2O2 solution to transform the Si-CH3 groups on their surfaces into Si-OH groups. Then, methylmethacryl groups were grafted onto the substrates through a silanization reaction using 3-(trimethoxysilyl) propylmethacrylate. Sequentially, cysteamine was conjugated on the silanized surfaces by the reaction between the thiol and methylmethacryl groups under UV 254 nm exposure. Afterwards, the amino-terminated PDMS substrates were sequentially reacted with CMC, CMD, and AA in the presence of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), resulting in the grafting of polysaccharides onto PDMS surfaces. The composition and chemical state of the modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS). In addition, the stability and dynamic characteristics of the polysaccharide-grafted PDMS substrates were investigated by XPS and temporal contact angle experiments. A protein adsorption assay using bovine serum albumin (BSA), chicken egg albumin, lysozyme, and RNase-A showed that the introduction of CMD and AA can reduce the adsorption of negatively-charged BSA and chicken egg albumin, but increase the adsorption of the positively-charged lysozyme and RNase-A. However, CMC-modified PDMS surfaces showed protein-repelling properties, regardless of whether the protein was positively- or negatively-charged. A cell culture and migration study of glioma C6, MKN-45, MCF-7, and HepG-2 cells revealed that the polysaccharide-modified PDMS greatly improved the cytocompatibility of native PDMS.