Immobilization of Ag nanoparticles on TiO2 nanotubes electrochemically formed on Ti-6Al-4V alloy

ALEJANDRA L. MARTÍNEZ; DANIEL O. FLAMINI; SILVANA B. SAIDMAN

Mar del Plata

Congreso; 34th Topical Meeting of The International Society of Electrochemistry; 2023

Universidad Nacional de Mar del Plata

Ti and its alloys have been extensively studied as biomaterials. Specifically, Ti-6Al-4V has been studied due to its good corrosion resistance, biocompatibility, low density and favorable mechanical properties. Regardless of its good characteristics, the release of the alloying elements into the physiological environment is a health risk that should not be ignored. It has been reported that Al and V are related with health issues like osteomalacia, peripheral neuropathy and Alzheimer?s disease [1]. For this reason, different techniques have been employed to modify the alloy surface in order to improve its corrosion behavior in physiological media. Furthermore, bacterial infection is the most frequent complication associated with biomaterials. Consequently, it is important that the material presents an effective antibacterial activity to prevent infections. Silver is an environmentally friendly material that has low toxicity and has been tested against different microorganisms [2]. In this work, TiO2 nanotubes (NTs) were electrochemically synthesized onto Ti-6Al-4V and then modified with Ag nanoparticles (AgNps) to enhance the corrosion behavior in Ringer solution and provide antibacterial activity against S. aureus and E. coli. Ti-6Al-4V in the form of rods axially mounted in a Teflon holder were used as working electrodes (WE) and a large Pt sheet of 1 cm2 area was used as reference electrode for nanotube formation. The exposed surface area of WE was 0.07 cm2. In order to form TiO2 nanotubes, the WE were immersed in a solution containing 1 M H3PO4 and 0.4 % (v/v) HF during 2 h at an applied potential of 20 V. The solution was under stirring during the anodization process. After this, the electrodes were rinsed in triply distilled water and introduced into a three electrode electrochemical cell containing 0.1 M KCl and 0.2 mM Ag(NO3)2 for the deposition of AgNps. For this process, a potential of -0.6 V was applied for 3s for AgNps nucleation, then a cyclic voltammetry was performed from -0.3 to 0 V for 40 cycles for the growth of them. The presence of AgNps was confirmed by scanning electron microscope (SEM) and X-ray energy dispersion (EDX). After the electrodeposition process, corrosion tests were carried out in Ringer solution through different electrochemical techniques: Tafel polarization curves, linear sweep voltammetry, chronoamperometry and open circuit potential measurements. It was found that the formation of TiO2 nanotubes, together with the presence of AgNPs, shifts the corrosion potential towards nobler values, maintaining a low corrosion current density. Finally, the antibacterial capacity of the coatings was evaluated. The Kirby-Bauer method [3] was used for this purpose. The strains studied were a culture of S. aureus and E. coli. The antibacterial capacity of the samples was determined considering the width of the inhibition zone around the modified surfaces. It was determined that the presence of AgNps reduced the bacterial growth obtaining inhibition halos of 15 mm.References1. A. Singh, and A.K. Dubey, ACS Applied Biomaterials 1 (2018) 3-20.2. S. Chernousova, M. Epple, Silver as antibacterial agent: Ion, nanoparticle, and metal, Angew. Chemie - Int. Ed. 52 (2013) 1636?16533. A.W. Bauer, W.M.M Hirby, J.C. Sherris, and M. Truck, American Journal of Clinical Pathology 45 (1966): 493-496.