Control of the degradation of silica sol-gel hybrid coatings for metal implants prepared by the triple combination of alkoxysilanes

Hybrid materials obtained by sol-gel process are able to degrade and release Si compounds that are useful in regenerative medicine due to their osteoinductive properties. The present work studies the behavior of new organic-inorganic sol-gel coatings based on triple mixtures of alkoxysilanes in different molar ratios. The precursors employed are methyl-trimethoxysilane (MTMOS), 3-glycidoxypropyl-trimethoxysilane (GPTMS) and tetraethyl-orthosilicate (TEOS). After optimization of the synthesis conditions, the coatings were characterized using 29Si nuclear magnetic resonance (29Si-MNR), Fourier transform infrared spectrometry (FT-IR), contact angle measurements, hydrolytic degradation assays, electrochemical impedance spectroscopy (EIS) and mechanical profilometry. The degradation and EIS results show that by controlling the amount of TEOS precursor in the coating it is possible to tune its degradation by hydrolysis, while keeping properties such as wettability at their optimum values for biomaterials application. The corrosion properties of the new coatings were also evaluated when applied to stainless steel substrate. The coatings showed an improvement of the anticorrosive properties of the steel which is important to protect the metal implants at the early stages of the regeneration process.The financial support of MAT2014-51918-C2-2-R, P11B2014-19 and Plan de Promoción de la Investigación from the Universitat Jaume I (Predoc/2014/25) is gratefully acknowledged. J. García-Cañadas acknowledge financial support from Ramón y Cajal programme (RYC-2013-13970). The experimental support of Raquel Oliver Valls and José Ortega Herreros is also acknowledged

A single coating with antibacterial properties for prevention of medical device-associated infections

Human bacterial pathogens found on medical implants are one of the main causes of morbidity and mortality, making the development of novel coatings the primary strategy in the prevention of medical device-associated infections. Here, we describe organic-inorganic hybrid coatings for metallic bone implants, based on sol-gel materials of proven osteogenic capacity. The coatings were doped with two bactericides: octenidine dihydrochloride (OCT) and chlorhexidine diacetate (CHX). These bactericides, known for their efficiency, are widely used in the prevention and elimination of bacterial infections. The coatings have good chemical and mechanical properties, making them suitable for use on medical devices. They also demonstrate strong antibacterial capacity, dependent on the concentration of the bactericide. They are not toxic to human osteoblasts. Our results suggest this system as a tool for coating medical devices to prevent bacterial infections