Cell attachment to laser-induced AAm- and HEMA-grafted ethylene-propylene rubber as biomaterial: in vivo study

With the purpose of improved tissue compatibility, ethylene-propylene rubber (EPR)-based vulcanizates have been surface grafted with acrylamide (AAm) and 2-hydroxyethyl methacrylate (HEMA) using CO2-pulsed laser as excitation source. Grafted surfaces were characterized by performing scanning electron microscopy combined with energy dispersive X-ray analysis and attenuated total reflectance infrared spectroscopy to study the surface morphology and grafting. Surface hydrophilicity (measured by water drop contact angle) increased for the grafted samples. Fractal type of morphology is formed by the grafted poly(AAm) and poly(HEMA) chains on the surface of EPR, which provides both hydrophilic and hydrophobic sites. In vivo tissue compatibility was assessed by implanting test samples in the deep intramuscular and peritoneal layers of rabbits. After 8 weeks of implantation, comparative results indicate that the adhesion of macrophages to EPR samples modified with AAm and HEMA, with no respiratory burst and cellular damage, is significantly lower than their adhesion on unmodified surfaces which show an activated state of the attached macrophages. Also, no acute or chronic inflammatory reaction was observed at the site of implantation and a thinner fibrous tissue capsule formed around the modified samples, whereas foreign body giant cells adhered to unmodified EPR.