Bactericidal efficacy of UV activated TiO2 nanoparticles against Gram-positive and Gram-negative bacteria on suspension

Abstract

Two different TiO2 nanoparticles, NM101 and NM105, were evaluated against a range of Gram-positive (Staphylococcus aureus, Bacillus cereus, Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus acidophilus and Lactobacillus lactis) and Gram-negative (Salmonella enterica var. Enteridis and Escherichia coli) bacteria. Both NM101 and NM105 TiO2 nanoparticles (UV-exposed or none) had a significant antibacterial activity when the concentration of TiO2 suspension was 100 µg mL−1. The activation of the TiO2 NPs led, in all cases, to a shift in the growth curve, revealing lower counts as the concentration increased. E. coli was the most significantly affected pathogen by both TiO2 nanoparticles reaching among 2–3 log CFU.mL−1 reduction. In addition, in the case of the probiotic bacteria, NM105 TiO2 nanoparticles had similar effects as the bacterial density was reduced by 2–3 log CFU.mL−1. These results may be applied as a potent technology to be included in the formulation of new disinfectants.