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

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.