Bactericidal efficacy of UV activated TiO2 nanoparticles against Gram-positive and Gram-negative bacteria on suspension Eficacia bactericida de nanopartículas de TiO2 activadas por luz UV contra bacterias Gram-positivas y Gram-negativas en suspensión

Two different TiO 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 TiO nanoparticles (UV-exposed or none) had a significant antibacterial activity when the concentration of TiO suspension was 100 µg mL. The activation of the TiO 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 TiO nanoparticles reaching among 2-3 log CFU.mL reduction. In addition, in the case of the probiotic bacteria, NM105 TiO nanoparticles had similar effects as the bacterial density was reduced by 2-3 log CFU.mL. These results may be applied as a potent technology to be included in the formulation of new disinfectants.