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Graft copolymerization by ionization radiation, characterization, and enzymatic activity of temperature-responsive SR-g-PNVCL loaded with lysozyme

Abstract:

Advanced polymeric materials suitable as components of implantable or insertable medical devices and endowed with the ability to host safe antimicrobial enzymes are attracting much attention. The aim of this work was to surface-modify silicone rubber (SR) films with N-vinylcaprolactam (NVCL) to reversibly load and release lysozyme. NVCL was first grafted onto SR film applying a direct gamma-ray irradiation method in order to provide SR with temperature-responsive hydrophilic nanobrushes coating. The effect of absorbed dose and monomer concentration on the grafting yield was studied in detail. Temperature-sensitive SR-g-NVCL films were characterized by FTIR-ATR, CP/MAS 13C NMR, DSC, TGA, and SEM. Elasticity properties of grafted films were recorded. The hydrophilicity of modified films was analyzed through swelling degree and water contact angle. The lower critical solution temperature (LCST) of SR-g-NVCL was studied in aqueous media. Lysozyme (Lyz) was successfully loaded onto graft copolymer surface via weak electrostatic and hydrophobic interactions. Antimicrobial activity of SR-g-PNVCL-Lyz films was demonstrated in vitro against Micrococcus lysodeikticus.