Immobilization of Zn species in a polypyrrole matrix to prevent corrosion and microbial growth on Ti-6Al-4V alloy for biomedical applications

Abstract

Polypyrrole (PPy) films were potentiostatically synthesized from an aqueous solution containing sodium salicylate (NaSa) on Ti-6Al-4 V alloy. In order to develop a coating to prevent corrosion and microbial growth on the alloy, the microstructured polymer matrix was employed for the immobilization of Zn species by means of two different methods. One of them involved the immobilization after the PPy electropolymerization (method 1) and the other one during the electrosynthesis process (method 2). The antimicrobial activity against Candida albicans and Staphylococcus aureus was evaluated. Only the coating obtained by method 2 showed antibacterial activity against S. aureus.To verify the acceptability of the coated samples for dental implant applications, the anticorrosive properties were evaluated by different electrochemical techniques (open circuit potential (OCP), linear sweep voltammetry (LSV), chronoamperometry (CA)) and electrochemical impedance spectroscopy (EIS) measurements). The electrolyte selected to simulate the intraoral condition was artificial saliva (AS) at pH 4 containing 0.20 % NaF. It was found that the electrode coated with unmodified and modified PPy showed a good corrosion protection behavior. The active dissolution process of the alloy was suppressed. Moreover, the coatings reduce the steady state current densities at 0.20 V (vs. saturated calomel electrode (SCE)) and decrease the release of Ti and V ions. No cracks or corrosion products were detected on the films after immersion in AS solution.