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

OBJECTIVE: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.