In-Situ Synthesis and Characterization of Chitosan/Hydroxyapatite Nanocomposite Coatings to Improve the Bioactive Properties of Ti6Al4V Substrates.

Zahra Ansari,Maria Grazia Raucci,Mahshid Kharaziha,Ines Fasolino,Alessandra Soriente,Mahdi Kalantar,Luigi Ambrosio

doi:10.3390/ma13173772

Abstract

Ti6Al4V alloy is still attracting great interest because of its application as an implant material for hard tissue repair. This research aims to produce and investigate in-situ chitosan/hydroxyapatite (CS/HA) nanocomposite coatings based on different amounts of HA (10, 50 and 60 wt.%) on alkali-treated Ti6Al4V substrate through the sol-gel process to enhance in vitro bioactivity. The influence of different contents of HA on the morphology, contact angle, roughness, adhesion strength, and in vitro bioactivity of the CS/HA coatings was studied. Results confirmed that, with increasing the HA content, the surface morphology of crack-free CS/HA coatings changed for nucleation modification and HA nanocrystals growth, and consequently, the surface roughness of the coatings increased. Furthermore, the bioactivity of the CS/HA nanocomposite coatings enhanced bone-like apatite layer formation on the material surface with increasing HA content. Moreover, CS/HA nanocomposite coatings were biocompatible and, in particular, CS/10 wt.% HA composition significantly promoted human mesenchymal stem cells (hMSCs) proliferation. In particular, these results demonstrate that the treatment strategy used during the bioprocess was able to improve in vitro properties enough to meet the clinical performance. Indeed, it is predicted that the dense and crack-free CS/HA nanocomposite coatings suggest good potential application as dental implants.

Highlights

Titanium (Ti)-based alloys, especially Ti6Al4V, having a high strength-to-weight ratio, low density, excellent corrosion resistance, low cytotoxicity, biocompatibility, and good mechanical properties, constitute one of the most used materials for biomedical applications [1,2]
This study aims to in-situ synthesize CS/HA nanocomposite coatings (HA content to 60 wt.%) on alkali-treated Ti6Al4V substrate via sol-gel process to obtain the crack-free coatings without any imperfection and pores
In order to mechanically interlock the coating to the substrate, alkali-treatment was performed

Summary

Introduction

Titanium (Ti)-based alloys, especially Ti6Al4V, having a high strength-to-weight ratio, low density, excellent corrosion resistance, low cytotoxicity, biocompatibility, and good mechanical properties, constitute one of the most used materials for biomedical applications [1,2]. The formation of an oxide layer on Ti decreased the dissolution rate of Ti implants in the biological environment. There is concern about the interaction of Ti-based implants with bone tissue after implantation as the oxide layer could not promote the formation of a hydroxyapatite layer and the bone could not directly bond to Ti6Al4V implants. Previous studies have reported high levels of Ti ions in the area of the Ti-based implants [2]. Materials 2020, 13, 3772 expanded to create interactions between Ti implants and the surrounding bone [3,4]. Hydroxyapatite (HA: Ca10 (PO4 ) (OH)2 ) coating as a principal inorganic element of natural bone can promote the formation of bone-like biological apatite on the implant surface [5]. Despite the advantages of HA for orthopedics and dental implant applications [6], its brittleness and low fracture toughness have been well-known as the main weaknesses of HA and have constrained its clinical applications [7,8]

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