Antimicrobial photocatalytic PANI based-composites for biomedical applications

Abstract

Surface contamination and transmission can lead to Hospital Acquired Infections (HAI) in a healthcare environment. To tackle this problem, a sustainable antimicrobial coating is desirable. Photocatalytic coatings with titanium dioxide (TiO2) as the main component activated by UV light are one option. In order to implement the coating in a real-world hospital setting the photocatalytic component must show activity under visible light. In this article the TiO2 photocatalyst was synthesised as both 2- and 3- component composites with polyaniline (PANI) or poly(aniline-co-3-aminobenzoic acid) (fPANI) and Ag nanoparticles to achieve photocatalytic performance activated by visible light. The UV-DRS results supported the visible light photocatalytic capability of both 2- and 3-component composite systems, and the ESR spectra exhibited the presence of charge carriers (unpaired electrons), which was confirmed by conductivity studies. The intensity of the ESR peak increases around 3-fold for PANI/fPANI-TiO2-Ag composites compared to pure PANI/fPANI. The conductivity of pure PANI and fPANI was only mildly enhanced in 3-component systems, which could be due to presence of TiO2, whereas the value increased by around three times for PANI/fPANI-Ag 2-component system due to conductive Ag nanoparticles. The composites with fPANI showed improved antimicrobial activity than PANI composites against three representative microorganisms Escherichia coli, Staphylococcus aureus and a model viral strain bacteriophage Phi X 174. Finally, we proposed a mechanism for photocatalytic activity for both 2- and 3- component systems.