Photocatalytic and antibacterial performance of β-cyclodextrin-TiO2 nanoparticles loading sorbic and benzoic acids

Abstract

TiO2 nanoparticles (NPs) have been modified with β-cyclodextrin (βCD)-food preservative complexes. The susceptibility of Escherichia coli and Staphylococcus aureus to TiO2 NPs, sorbic acid (SA), benzoic acid (BA), and β-Cyclodextrin-TiO2 NPs including SA or BA, was studied. At 0.5 mg mL−1, TiO2 NPs were more effective in the inhibition of bacterial growth than modified-TiO2 NPs, achieving 71% inhibition rate. At the higher concentration of 3 mg mL−1 there were no significant differences between treatments, being all of them highly effective reaching 90% inhibition. Higher treatment-doses were related to slower growth rates. Flow cytometry findings suggested efficient NPs interaction with bacteria, being more noticeable in the case of TiO2 NPs. Regarding the photocatalytic activity, under 0.600 mW cm−2 irradiation, TiO2 NPs reached 95% methylene-blue dye degradation after 150 min, while βCD-TiO2 NPs showed 3-times lower kinetic constant. Overall results suggest potential application of the new systems in active packages to protect food from microbial spoilage.