Influence of Si3N4 and CuO Nanoparticles on the Microstructure and Properties of Multiphase Graphite Oxide/Hydroxyapatite/Sodium Alginate Coatings Obtained By Electrophoretic Deposition on Titanium Alloy

Abstract

In this work, we report an electrophoretic deposition path for efficient fabrication of advanced multiphase coatings, consisting of Ca cross-linked sodium alginate with graphite oxide n-GtO flakes mixed into bioactive hydroxyapatite and CuO or Si3N4 antibacterial nanoparticles. Anionic sodium alginate molecules ensured electrosteric stabilisation of the suspension. The effects of the chemical composition of the suspension and deposition parameters on coating morphology were investigated. Hydroxyapatite and antibacterial agents formed agglomerates fairly well spread within the alginate matrix. The coatings with Si3N4 incorporation presented outstanding adhesion to the Ti-13Nb-13Zr alloy substrates. All coatings revealed hydrophilic surfaces and showed a high ability to protect the alloy substrates from corrosion in Ringer’s solution. A hydroxyapatite layer was formed as a result of soaking the coated samples in simulated body fluid for 3 weeks. CuO-containing samples showed significantly improved antibacterial properties against E. coli. The incorporation of n-GtO alone did not induce any cytotoxic effects of the coatings against MG-63 cells but its combination with CuO and Si3N4 reduced the cell viability. However, this behaviour was much more pronounced for the CuO-containing coatings. This work demonstrates the outstanding development potential of electrophoretically deposited multifunctional coatings with potential application in long-term titanium bone implants.