Surface modification of poly-L-lactic acid (PLLA) membrane by grafting acrylamide: an effective way to improve cytocompatibility for chondrocytes

Poly-L-lactic acid (PLLA) membranes were photo-oxidized in hydrogen peroxide solution under ultraviolet light (UV) to introduce hydroperoxide groups onto the PLLA membrane surfaces. The photo-oxidized membranes were then immersed in acrylamide (AAm) solution containing Fe2+ to graft polyacrylamide (PAAm) onto the PLLA membrane surfaces. The density of the hydroperoxide groups introduced on the PLLA membrane surfaces varied with the temperature and the photo-oxidization time. The occurrence of grafting was verified by X-ray photoelectron spectroscopy (XPS). The degree of grafting increased with the monomer concentration and the polymerization time. Water contact angle measurements showed that the wettability of the modified PLLA membranes had improved. Chondrocytes proliferated more rapidly and were more spread out on the modified membrane than on the control PLLA membrane, indicating that the PAAm-grafted PLLA membrane has better cytocompatibility for chondrocytes.