Grafting of architecture controlled poly(styrene sodium sulfonate) onto titanium surfaces using bio-adhesive molecules: Surface characterization and biological properties.

This contribution reports on grafting of bioactive polymers such as poly(sodium styrene sulfonate) (polyNaSS) onto titanium (Ti) surfaces. This grafting process uses a modified dopamine as an anchor molecule to link polyNaSS to the Ti surface. The grafting process combines reversible addition-fragmentation chain transfer polymerization, postpolymerization modification, and thiol-ene chemistry. The first step in the process is to synthetize architecture controlled polyNaSS with a thiol end group. The second step is the adhesion of the dopamine acrylamide (DA) anchor onto the Ti surfaces. The last step is grafting polyNaSS to the DA-modified Ti surfaces. The modified dopamine anchor group with its bioadhesive properties is essential to link bioactive polymers to the Ti surface. The polymers are characterized by conventional methods (nuclear magnetic resonance, size exclusion chromatography, and attenuated total reflection-Fourier-transformed infrared), and the grafting is characterized by x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and quartz crystal microbalance with dissipation monitoring. To illustrate the biocompatibility of the grafted Ti-DA-polyNaSS surfaces, their interactions with proteins (albumin and fibronectin) and cells are investigated. Both albumin and fibronectin are readily adsorbed onto Ti-DA-polyNaSS surfaces. The biocompatibility of modified Ti-DA-polyNaSS and control ungrafted Ti surfaces is tested using human bone cells (Saos-2) in cell culture for cell adhesion, proliferation, differentiation, and mineralization. This study presents a new, simple way to graft bioactive polymers onto Ti surfaces using a catechol intermediary with the aim of demonstrating the biocompatibility of these size controlled polyNaSS grafted surfaces.