A fibrous titanium phosphate as repository for silver on modified surfaces of titanium and titanium alloys

Abstract

Silver is a metal known for its antimicrobial activity against Gram-positive and Gram-negative bacteria, including antibiotic-resistant strains, fungi, protozoa and certain viruses. It is used for treatment of infections, preventing bacterial colonization on medical devices and for water treatment. Silver, as an antiseptic agent, is efficient while present in glass, titanium and polymers. This motivates its use in biomedical applications, water and air purification, food production, cosmetics, clothing and numerous household products. Titanium and its alloys were widely used as artificial joints, bone fixation devices or dental implants, in orthopedic field, mainly due to their great mechanical properties, corrosion resistance and biocompatibility. However, some shortcomings of native titanium were found to hinder its osteointegration and even affect the long-term survival of Ti-based implants. The deposition of nanostructured thin films of certain inorganic compounds on the surface of a metal, thus creating thin film/metal composites, is of particular interest in this field. It has been shown that the materials composed of titanium-based coatings on the Ti-metal surfaces can be used as implants with excellent apatite-forming and antibacterial abilities. Recently, the surface wettability control has attracted significant attention because of the promising applications of superhydrophobic and superhydrophilic materials for self-cleaning, corrosion resistant, fluidic drag reduction, and oil-water separation. In this way, Yada et al. has reported the superhydrophilicity and superhydrophobicity properties of π-titanium phosphate nanorod thin films modified with alkylamine molecules (the first synthesis of π-Ti2O(PO4)2·2H2O was reported by our Lab in the end of the last century), while Lu has described the thin film preparation composed of π-titanium phosphate nanorods by performing a hydrothermal treatment of a titanium plate in phosphoric acid solution at 250 °C. Finally, Park et al. by performing a hydrothermal treatment of the titanium plate in phosphoric acid solution at 180 °C has also obtained a π-titanium phosphate thin film of approximately 5 μm thick and having needle-like surface microstructures. In this context, the present communication is devoted to the ability of π-titanium phosphate to the intra-crystalline incorporation of silver(I) cations as a way for the trapping of bioactive metals into a neutrally charged framework, with the consecutive incorporation of the produced material into titanium (and titanium alloys) surfaces.