Electrophoretic deposition of vancomycin loaded halloysite nanotubes-chitosan nanocomposite coatings

The vancomycin loaded halloysite nanotubes (HNTs)/chitosan nanocomposite coating with drug delivery and antibacterial activity was fabricated by electrophoretic deposition (EPD) on titanium substrate. Suspensions of HNTs were prepared in different alcohols containing water, chitosan and acetic acid (AA). The amount of chitosan adsorbed on HNTs decreased with increasing the AA concentration. In contrast to isopropanolic suspensions, the zeta potential of HNTs decreased with increasing the AA content in methanolic and ethanolic ones. Current density increased or remained nearly constant during EPD for all suspensions due to the increased electrolysis of water. Despite of the lowest zeta potential, the coating deposited from isopropanolic suspension with 0.1 vol% of AA had the finest microstructure and the lowest roughness. Coatings were characterized by microstructural (SEM and AFM), thermal (TG/DTA) and mechanical (pull-off adhesion test) analyses. Ethanolic suspension with 1 vol% of AA was selected as the optimum suspension and drug (vancomycin) loaded coating was prepared using it. The coating exhibited desired drug release profile: initial burst release and then long term slow release. The loading of coating with vancomycin increased (about 27%) its antibacterial performance against Gram-positive Staphylococcus aureus bacteria.