Effect of modification of titanium surfaces to graft poly(ethylene glycol)methacrylate-arginine-glycine-aspartic polymer brushes on bacterial adhesion and osteoblast cell attachment

Abstract

To study the effect of poly(ethylene glycol)methacrylate(PEG)-arginine-glycine-aspartic(RGD)polymer brushes graft on bacterial adhesion and MC3T3 osteoblast cell attachment on titanium, and to investigate if the modification of titanium will enable the implant to be anti-fouling and promot osteointegration. PEG was tethered on titanium surface modified with 2-bromoisobutyryl bromide(denoted as Ti-Br)to form Ti-PEG brushes. Functionalization of the Ti-PEG surface with RGD was performed to form Ti-PEG-RGD brushes. The chemical composition of modified titanium surfaces was characterized by X-ray photoelectron spectroscopy(XPS). Changes in surface hydrophilicity and hydrophobicity were characterized by static water contact angle measurements. Streptococcus mutans(Sm), Actinomyces naeslundii(An)and osteoblast cell were cultured on pure titanium(Ti), Ti-PEG, Ti-PEG-RGD surfaces respectively. There were ten samples in each group. The bacterial adhesion ability and cell attachment were confirmed by fluorescence microscopy and scanning electron microscopy(SEM). The static water contact angle of Ti, Ti-Br, Ti-PEG, Ti-PEG-RGD was less than 10°, 80°, 45°, 55° respectively. XPS confirmed that PEG-RGD brushes were successfully tethered on titanium surfaces. Anti-bacterial test showed that on the pure-Ti, there were large amount of bacteria from both groups, however, in the Ti-PEG, Ti-PEG-RGD surfaces, both kind of bacteria were rare and distributed diffusely. Cell culture test showed that on the Ti-PEG-RGD surfaces, the number of cells was significantly more than that on the Ti and the Ti-PEG surfaces. PEG can inhibit both kind of bacteria adhesion and osteoblast cell attachment, and PEG-RGD brushes can not only inhibit bacterial adhesion but also promote osteoblast cell attachment.