Anodic tio2 nanotubes: Tailoring osteoinduction via drug delivery

TiO2 nanostructures and more specifically nanotubes have gained significant attention in biomedical applications, due to their controlled nanoscale topography in the sub-100 nm range, high surface area, chemical resistance, and biocompatibility. Here we review the crucial aspects related to morphology and properties of TiO2 nanotubes obtained by electrochemical anodization of titanium for the biomedical field. Following the discussion of TiO2 nanotopographical characterization, the advantages of anodic TiO2 nanotubes will be introduced, such as their high surface area controlled by the morphological parameters (diameter and length), which provides better adsorp-tion/linkage of bioactive molecules. We further discuss the key interactions with bone-related cells including osteoblast and stem cells in in vitro cell culture conditions, thus evaluating the cell response on various nanotubular structures. In addition, the synergistic effects of electrical stimulation on cells for enhancing bone formation combining with the nanoscale environmental cues from nanotopography will be further discussed. The present review also overviews the current state of drug delivery applications using TiO2 nanotubes for increased osseointegration and discusses the advantages, drawbacks, and prospects of drug delivery applications via these anodic TiO2 nano-tubes.