Antibiofilm and antioxidant biocompatible materials as thin films based on a PVB matrix loaded with quercetin

The development of bacterial biofilms is a concern to public health as they play a crucial role in the management of infections, hence enhancing chronic infection occurrence. Phytochemicals such as quercetin (QCT), alone or combined with traditional antimicrobials, are promising natural resources to combat biofilm-associated infections. In this work, a biocompatible material, polyvinyl butyral was processed into thin films and loaded with quercetin (0-11 wt%) in order to exploit its antibiofilm and antioxidant activity. These films were characterized for their morphology, wettability and by structural analysis. The in vitro release of quercetin was investigated in sodium phosphate buffer (PBS, 50 mM, pH 7.4, 37 °C). The effect of the released flavonoid on biofilm formation of Staphylococcus aureus strains, including methicillin resistant S. aureus (MRSA), was evaluated as well. The films formulated with 7% of QCT resulted in a 68% and73% inhibition of S. aureus ATCC 6538 and MRSA biofilms, respectively. The antioxidant activity of the membranes was determined by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, which showed DPPH radical inhibition up to 50% over the range of loaded QCT concentrations. Furthermore, the potential toxicity of the films was assessed by the Artemia salina Leach lethality bioassay, which evidenced the absence of toxicity against brine shrimp larvae. The overall results suggest the use of the novel PVB-based membranes as strategic tools for quercetin delivery and to control biofilm formation of S. aureus strains.