Electrochemical characterization of coatings for local prevention of Candida infections on titanium-based biomaterials

Prosthetic Joint Infections (PJI) are one of the most dangerous and devastating complications following total joint replacement, with important implications for patient health and high costs for Public Health. Fungi infections are a concern for the orthopedic community due to their recent increasing incidence and their resistance to antifungals. Nowadays, these infections are prevented by the prophylactic administration of antifungals. In this research, we propose an alternative to this approach through the local prevention of the infections using coatings deposited on the implants and loaded with antifungals. In this manner, new biodegradable coatings were synthesized with antifungals incorporation for the drug local release. Coatings were prepared using sol-gel technology based on 3-(trimethoxysilyl)propyl methacrylate (MAPTMS) and tetramethyl orthosilicate (TMOS). Two different fungicides (fluconazole and anidulafungin) were separately introduced at different concentrations. Coatings were deposited on powder metallurgical titanium (TiPM) substrates by dip-coating technique. After determination of the optimal synthesis parameters to obtain homogeneous films, coatings were physicochemically characterized by Scanning Electron Microscopy (SEM), Si-29 Nuclear Magnetic Resonance (Si-29 NMR), Thermogravimetric analysis (TGA), Contact Angle measurements and Electrochemical Impedance Spectroscopy (EIS) tests. Studies of drug release, cytotoxicity, biofilm inhibitory capacity, and hydrolytic degradation were also performed. This study demonstrated that the release of the physically-trapped in the polysiloxane network antifungals is proportional to the degradation of the coatings. In addition, the degradation kinetics in fluconazole-laden coatings were different from those loaded with anidulafungin and depended on the chosen precursors and their molar ratio and the molecular weight and concentration of the incorporated drug. Synthesized coatings loaded with anidulafungin are presented as an alternative to prevent PJI since in vitro tests performed demonstrated their non-cytotoxicity accompanied by antifungal effectiveness.