Characterization and biological properties of TiO2/PCL hybrid layers prepared via sol-gel dip coating for surface modification of titanium implants

Surface modification of implants to facilitate the integration process of the biomaterials is a strategy which has been attracting increasing attention. In this work, the sol-gel method has been used to synthesize organic-inorganic nanocomposite materials consisting of an inorganic titania matrix in which different percentages of a biocompatible polymer, the poly-epsilon-caprolactone (PCL), have been incorporated. The synthesized materials, still in sol phase, have been used to dip-coat titanium grade 4 substrates to improve the biological properties of the surface. Fourier transform infrared spectroscopy detected the formation of H-bonds between the C=O of PCL chains and the -OH groups of the sol-gel matrix. The morphological analysis of films has been performed via scanning electron microscopy (SEM) and has shown that the PCL addition allows the preparation of crack-free and porous coatings; however, uncoated areas develop if PCL is present in high percentages. Bioactivity properties of the coatings have been investigated by soaking coated substrates in a fluid simulating the human blood plasma and evaluating at a later stage the formation of a hydroxyapatite layer on the surface by means of SEM/EDX (energy dispersive X-ray). Coating biocompatibility has been studied by WST-8 assay using 3T3 cells seeded on coated and uncoated substrates. (C) 2015 Elsevier B.V. All rights reserved.