Gallium oxide nanoparticle induced inhibition of bacterial adhesion and biofilm formation

Toxicity of nano scaled Ga₂O₃ and functionalized (carboxyl -COOH; amine -NH) nanoparticles was examined against a gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. NP concentrations in the range of 0.25 to 25 μg/mL were tested. Strain specificity in antimicrobial activity was observed. Ga₂O₃ treatments resulted in 26% inhibition of growth of planktonic cells in S. aureus at the lowest concentration of 0.25 μg/mL. Carboxyl functionalization resulted in a higher percentage of inhibition than that for amine functionalization in the growth of planktonic cells. In comparison, the gram negative strain (E. coli) has shown an increase in planktonic cell growth on treatment with Ga₂O₃ nanoparticles. The increase is lower in case of Ga₂O₃ treatment alone than those observed for COOH and NH modification. In contrast to planktonic cells, Ga₂O₃ and its functional groups retard biofilm formation even when high percentage of planktonic S. aureus and E. coli cells have survived the treatment. Higher percentage inhibition of biofilms is observed with both the functional groups. In comparison, higher percentage inhibition of biofilms is observed in the case of E. coli at the lowest concentration tested, when more than 100% of the planktonic cells survived the treatment. Results indicate that Ga₂O₃ may be involved in interfering with the molecular mechanisms.