Functionalization of titanium surfaces via controlled living radical polymerization: From antibacterial surface to surface for osteoblast adhesion

Abstract

Controlled surface graft polymerizations allowed a wide range of functionalities, from antibacterial effects to cell adhesion properties, to be imparted on titanium surfaces. A trichlorosilane coupling agent, containing an atom-transfer radical polymerization (ATRP) initiator, was first immobilized on the oxidized titanium (Ti-OH) surface to cater for the surface-initiated ATRP of 2-hydroxyethyl methacrylate (HEMA). The pendant hydroxyl end groups of the grafted HEMA chains were subsequently converted into carboxyl or amine groups to allow the coupling of gentamicin, penicillin, or collagen via the carbodiimide chemistry. The functionalized Ti surfaces were characterized by X-ray photoelectron spectroscopy and assayed for antibacterial activities or cell adhesion properties. The covalently immobilized antibiotics retain the antibacterial properties, as indicated by a significant reduction in the viability of contacting Staphylococcus aureus. The collagen-immobilized surfaces, on the other hand, promote fibroblast and osteoblast cells adhesion and proliferation. Thus, the present surface-initiated living radical graft polymerization technique allows the tailoring of the Ti surface with vastly different functions and is potentially useful to the design or improvement of Ti-based biomedical implants. © 2007 American Chemical Society.