Sol–gel coatings for protection and bioactivation of metals used in orthopaedic devices

Abstract

The aim of this work is the production and characterisation of sol-gel coatings for protection and bioactivation of metals used as standard surgical implant materials, such as stainless steel 316 L (ASTM F138), Co based alloys (ASTM F75) and titanium alloy Ti-6Al-4V (ASTM F67). These films should both prevent degradation of the substrates by wear or corrosion, and bioactivate the material for inducing the formation of a hydroxyapatite (HA) rich layer onto the material surface, thereby permitting a natural bonding to living tissues. Formation of HA layers can be observed on performing in vitro tests by soaking the material in simulated body solutions. The work describes the development of coatings containing bioactive glass and glass-ceramic particles in hybrid methyl-triethoxysilane (MTES) and tetraethylorthosilicate (TEOS) acidic sol, applied by dip-coating to surgical alloys, AISI 316 L, ASTM F75 and ASTM 67, with the aim of accomplishing both high corrosion resistance of the metal in the body environment and adhesion of the implant to the surrounding tissue. The performance of the coated metal was evaluated in vitro by electrochemical techniques including potentiodynamic polarisation curves and electrochemical impedance spectroscopy, to follow the formation of hydroxyapatite on the surface, as well as the in vitro release of ions by plasma atomic emission spectroscopy (ICP-MS) after up to one year of immersion. In vivo behaviour was evaluated by subcutaneous tests and endomedullar implantation in Hokaido rats to study possible rejection reactions and natural bonding to living tissue.

Surface engineering of titanium thin films with silk fibroin via layer‐by‐layer technique and its effects on osteoblast growth behavior

“…This is the main stream of biomedical materials research in the future. 5 Titanium and its alloys are well known to be biocompatible materials, which were extensively used in dental 6 and orthopedic 7 as well as cardiovascular 8 fields for manufacturing medical devices, such as dental implants or hip-joint replacement devices as well as for heart-valves and cardiac pacemakers. However, even if a titanium implant osseo-integrates, it is only passively integrated with bone and, as other metals; it cannot directly bind to bone.…”

Sol-Gel SiO2-CaO-P2O5 biofilm with surface engineered for medical application

“…A great number of materials are used today to replace damaged bones and tissues, including metallic materials due to their excellent mechanical properties, such as strength and hardness. Unfortunately, these materials have two main disadvantages: 1) the tendency to release metallic ions when exposed to body fluids and 2) the formation of a non-adherent fibrous capsule around implant [6][7][8][9][10] . Considering these disadvantages, ceramic materials (bioactive materials) have been successfully used to coat metallic materials for decades.…”

Build up of multilayered thin films with chitosan/DNA pairs on poly(D,L‐lactic acid) films: Physical chemistry and sustained release behavior

“…Surface engineering or modification of a biomedical device based materials is a major research topic. [3][4][5] The main reason is that the biological response to tissues of an implant is mainly dominated by the biomaterial surface properties, via the interactions with components of the biological surroundings for a given application. 6 Cell and/or gene-activated material are the advanced requirement for biomaterials research in the future to generate a new functional biomaterial.…”