Adsorption behavior of serum proteins on anodized titanium is driven by surface nanomorphology

Protein adsorption behavior can play a critical role in defining the outcome of a material by affecting the subsequent in vivo response to it. To date, the effect of surface properties on protein adsorption behavior has been mainly focused on surface chemistry, but research on the effect of nanoscale surface topography remains limited. In this study, the adsorption behavior of human serum albumin, immunoglobulin G, and fibrinogen in terms of the adsorbed amount and conformational changes were investigated on bare and anodized titanium (Ti) samples (40 and 60 V applied voltages). While the surface chemistry, RMS surface roughness, and arithmetic surface roughness of the anodized samples were similar, they had distinctly different nanomorphologies identified by atomic force microscopy and scanning electron microscopy, and the surface statistical parameters, surface skewness Ssk and kurtosis Sku. The Feret pore size distribution was more uniform on the 60 V sample, and surface nanostructures were more symmetrical with higher peaks and deeper pores. On the other hand, the 40 V sample surface presented a nonuniform pore size distribution and asymmetrical surface nanostructures with lower peaks and shallower pores. The amount of surface-adsorbed protein increased on the sample surfaces in the order of Ti < 40 V < 60 V with the predominant factor affecting the amount of surface-adsorbed protein being the increased surface area attained by pore formation. The secondary structure of all adsorbed proteins deviated from that of their native counterparts. While comparing the secondary structure components of proteins on anodized surfaces, it was observed that all three proteins retained more of their secondary structure composition on the surface with more uniform and symmetrical nanofeatures than the surface having asymmetrical nanostructures. Our results suggest that the nanomorphology of the peaks and outer walls of the nanotubes can significantly influence the conformation of adsorbed serum proteins, even for surfaces having similar roughness values.

Impact of surface topography and coating on osteogenesis and bacterial attachment on titanium implants

Titanium (Ti) plays a predominant role as the material of choice in orthopaedic and dental implants. Despite the majority of Ti implants having long-term success, premature failure due to unsuccessful osseointegration leading to aseptic loosening is still too common. Recently, surface topography modification and biological/non-biological coatings have been integrated into orthopaedic/dental implants in order to mimic the surrounding biological environment as well as reduce the inflammation/infection that may occur. In this review, we summarize the impact of various Ti coatings on cell behaviour both in vivo and in vitro. First, we focus on the Ti surface properties and their effects on osteogenesis and then on bacterial adhesion and viability. We conclude from the current literature that surface modification of Ti implants can be generated that offer both osteoinductive and antimicrobial properties.