Production, Characterization and Application of Oxide Nanotubes on Ti–6Al–7Nb Alloy as a Potential Drug Carrier

Abstract

This work concerns the development of a method of functionalization of the surface of the biomedical Ti–6Al–7Nb alloy by producing oxide nanotubes (ONTs) with drug-eluting properties. Shaping of the morphology, microstructure, and thickness of the oxide layer was carried out by anodization in an aqueous solution of 1 M ethylene glycol with the addition of 0.2 M NH4F in the voltage range 5–100 V for 15–60 min at room temperature. The characterization of the physicochemical properties of the obtained ONTs was performed using SEM, XPS, and EDAX methods. ONTs have been shown to be composed mainly of TiO2, Al2O3, and Nb2O5. Single-walled ONTs with the largest specific surface area of 600 cm2 cm−2 can be obtained by anodization at 50 V for 60 min. The mechanism of ONT formation on the Ti–6Al–7Nb alloy was studied in detail. Gentamicin sulfate loaded into ONTs was studied using FTIR, TG, DTA, and DTG methods. Drug release kinetics was determined by UV–Vis spectrophotometry. The obtained ONTs can be proposed for use in modern implantology as carriers for drugs delivered locally in inflammatory conditions.

Production and Characterization of the Third-Generation Oxide Nanotubes on Ti-13Zr-13Nb Alloy

“…SWNTs can be produced electrochemically on the surface of the Ti-13Zr-13Nb electrode in 1 M C 2 H 6 O 2 electrolyte in the presence of F − ions, which can form water-soluble complexes with Ti, Zr, and Nb according to the Reactions (1)–(3) [ 11 , 12 , 49 , 50 ]: …”

“…Simultaneously, the fluoride ions inhibit the deposition of titanium hydroxides on the oxide layer. Reaction (4) describes the complexation of Ti 4+ ions, which migrate to the oxide surface and are ejected at the interface [ 12 , 49 , 50 ]: …”

“…The method of preparing the electrodes is described in detail in an earlier work [ 12 ]. To remove oxides from the Ti-13Zr-13Nb alloy surface, immediately before anodizing, each electrode with a geometric surface area of 3.14 cm 2 was immersed in 25% v / v HNO 3 (Avantor Performance Materials Poland S.A., Gliwice, Poland) for 10 min at room temperature and then re-cleaned with Milli-Q water in an ultrasonic bath for 20 min at room temperature.…”

“…However, the use of toxic alloying additives such as Al and V has been shown to pose a health risk to patients due to their harmful properties, including the induction of allergies, inflammation, Alzheimer’s disease, neuropathy, and more [ 4 , 10 ]. Titanium-based implants containing toxic vanadium are gradually being replaced by vanadium-free titanium alloys containing more biocompatible alloying additives in the form of Mo, Nb, Zr, and Ta, which can also stabilize the β structure in titanium [ 11 , 12 , 13 , 14 , 15 ].…”

“…Obtaining a porous surface of the Ti-13Zr-13Nb alloy enables the development of innovative long-term implants with increased osteoinductive properties. Recently, it was reported that the oxide nanotubes (ONTs) layer on the surface of titanium and its alloys could also be a carrier for drugs delivered to a specific place and enable their controlled release into the body at a specific rate, depending on the size of the nanotubes [ 12 ]. Due to their eluting properties, the ONTs can act as micro- or nano-syringes filled with medicinal, bactericidal, or tissue-forming substances.…”