Electrophoretic deposition and characterization of composite chitosan/ Eudragit E 100 or poly(4-vinylpyridine)/mesoporous bioactive glass nanoparticles coatings on pre-treated titanium for implant applications

Titanium implants are surface-modified to achieve bioactivity and often antibacterial properties. Such surface coatings may increase corrosion degradation and be weakly attached to the substrate. In the present research, biodegradable composite coatings, investigated so far as smart environment-sensitive, slowly releasing silver to the implant neighborhood, were produced as a combination of chitosan (CS) with Eudragit E 100 (EE100) or poly (4-vinylpyridine) (P4VP) polymers incorporating mesoporous bioactive glass nanoparticles (MBGNs). Such coatings were designed to positively affect corrosion resistance, bioactivity in vitro, and the bonding to the surface. The coating was obtained in a single electrophoretic deposition (EPD) process on the surface of chemically etched grade 2 titanium. The deposition was carried out using an ethanol-based suspension for 5 min at 60 V. Suspension stability was assessed through the quantification of zeta potential. The fabricated coatings underwent microstructural analysis, chemical composition profiling, surface roughness measurement, wettability assessment, thickness determination, evaluation of corrosion resistance, and investigation of their adherence to metallic substrates. Additionally, an immersion test extending up to 14 days was employed to assess the coatings' capacity for calcium phosphate formation. The resulting coatings tightly covered the metallic substrate; the CS/ EE100/MBGNs coating exhibited superior uniformity, which can be attributed to the increased stability of this suspension, indicated by a higher zeta potential value. The deposited MBGNs showed a diameter of <100 nm. The prepared coatings have contributed to improved corrosion resistance of the system and facilitated the deposition of calcium phosphates. All investigated surfaces showed hydrophilic properties. Substrate-coating adhesion was notably enhanced for the CS/EE100/MBGNs coating. The proposed coatings, after in vitro and in vivo cytotoxicity studies, can successfully be applied on long-term load-bearing titanium bone implants.