New approaches regarding the electrochemical behaviour of the Ti-6Al-4V alloy functionalized with antimicrobial peptide JI-2 via plasma polymerization

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Ti-6Al-4V alloy is widely used in the biomedical sector due to its excellent biocompatibility, corrosion resistance, and mechanical properties. However, the use of this material as an implant is still susceptible to failure due to bacterial adhesion on the surface. Initial studies performed by this research group demonstrated and characterized the functionalization process of the Ti-6Al-4V alloy with antimicrobial JI-2 peptide via plasma polymerization method. However, the electrochemical properties of the functionalized system are still little explored. Here, we present new insights regarding the global electrochemical behaviour of the functionalized Ti-6Al-4V with PAA/JI-2 in 0.6 mol L-1 NaCl solution. Open circuit potential and electrochemical impedance spectroscopy techniques were used. The electrochemical tests were accompanied by a detailed microstructural analysis by SEM. The results demonstrated the PECVD technique was advantageous to produce thin films based on acrylic acid monomer on the Ti-6Al-4V surfaces. The PAA/JI-2 thin films shifted the corrosion potential (Ecorr) of the Ti-6Al-4V alloy to more positive values, indicating a better thermodynamic stability. The capacitance of the barrier layer decreases for the uncoated specimens with increasing immersion time, suggesting an increase in the thickness of the native oxide layer. In contrast, the opposite effect was verified for the Ti-6Al-4V/PAA/JI-2.