Osteogenic potential of graphene coated titanium is independent of transfer technique

Abstract

The rapid integration of titanium implants into native bone remains a challenge in orthopedics and dental im- plantology. Several surface modifications have been attempted, but with limited success. Graphene coating has emerged as a candidate for shortening integration time due to its osteogenic potential. The wet transfer technique (WGp) is widely used to demonstrate graphene’s osteogenic potential but it is laborious and time-consuming, hence compromising industrial scalability and market adoption. Moreover, this transfer method traps water be- tween the coating and the target substrate, which can further deteriorate the coating and compromise its clinical translation even more. Alternatively, the dry transfer (DGp) method, based on the mechanized application of pressurized heat, allows graphene films to be transferred directly from a tape onto titanium in few minutes at a low cost. Here, we show that a single dry transfer procedure can coat > 90% of titanium samples with graphene. Compared with uncoated titanium, DGp increased the expression of cellular adhesion and collagen-related genes, collagen production, and bone formation. Raman and atomic force microscopy showed that cellular structures and stiffness were similar to those observed on uncoated titanium and X-ray powder diffraction confirmed that DGp favors the early formation of octacalcium phosphate. The results demonstrating the potential of DGp were similar to WGp, confirming that the changes in transfer procedures performed to improve the likelihood of in- dustrial scalability and clinical translation do not compromise the osteogenic potential of the graphene coating on titanium.