Coating of metalic implant surfaces with bio compatible polymers to have bio activity

ABSTRACT The aim of the study is to coat 316L stainless steel which is used as an implant material with bio-compatible poly (HEMA-GDMA) by electropolymerization method in order to develop the functionality and the bio-compatibility of the coatings. In the electropolymerization cell, (NH4)2S2O8 and (H2SO4) were used as initiators, HEMA was used as the monomer, GDMA was the cross-linker, 316L stainless steel was the working electrode, graphite rod was the counter electrode and SCE (saturated calomel electrode) was used as the referance electrode. Also, Na2SO4 was added to improve the conductivity of the solution. The thickness and homogenity of the coatings differ depending on the type of the initiator used and concentrations of the initiator, monomer and the cosslinker. Also, applied potential, number of cycles and scan rates are important as CV parameters. In this study, these parameters were tried to be optimized and coatings with different thickness and adhesion properties were obtained. Corrosion potentials of the coatings were measured using potantiostat-galvanostat and electrochemical parameters were obtained from TAFEL extrapolatation technique. Also, water content determination was done to characterize the swelling behaviour of the hydrogel coatings. The tendency of Ca-P deposition on the coatings was explored either by immersing them in a simulated body fluid or by an urea assisted mineralization technique. MG63 human osteoblast-like cells were used to assess the biocompatibility of the hydrogel coatings. Surface morphologies of the coatings, cell adhesion and spreading, and presence of Ca-P minerals on the coatings were examined by SEM. Chemical characterizations were done using EDS, XRD and FT-IR. Thickness and roughness values of the coatings were obtained by the surface profilometer device. Keywords: Electropolymerization; Hydrogel; Biomineralization; Biomaterial; Corrosion