TiO2 21 nm nanoparticles as a photocatalytic antimicrobial agent against Escherichia coli, Candida albicans and Methicillin resistant Staphylococcus aureus: A comparison

Objectives: To determine and compare the antimicrobial activity of 21 nm TiO2 nanoparticles against Escherichia colii, Candida albicans and Methicillin resistant Staphylococcus aureus (MRSA).Methods: Titanium dioxide (TiO2) 21 nm anatase nanoparticles (13.9 g/l) were suspended in miliQ (MQ) water, sonicated (35 MHz for 1 hour) and autoclaved. Sterile glass petriplates were treated with TiO2 suspension or sterile MQ(control). Overnight cultures of E.coli MRSA and C. albicans were added to TiO2 coated plates and control plates and kept at room temperature. Viable counts were obtained by spread plate method at 0 hours and 24 hours; before and after sunlight exposure for 30 minutes. Colony forming units (CFU) / ml was calculated to determine percentage reduction of CFU in presence of TiO2. Experiments were done in triplicates.Results: TiO2 nanoparticles demonstrated antimicrobial activity against E.coli, MRSA and C. albicans. Estimated percentage CFU reduction in E.coli (13±8.4), MRSA (12±6.6) and C. albicans (36±4.9 ) was observed at 0 hours of contact in the supernatant. The bactericidal effect was enhanced on exposure of the plates to sunlight. Estimated percentage CFU reductions are E. coli (46±7.9), MRSA (99±0.2 ) and C. albicans (99±0.4). The results for 24 hours were (95±1 ), (35±2.1 ) and (83±4 ) reduction for E. coli, MRSA and C. albicans respectively. When the 24 hour plates were exposed to sunlight (99±0.6), (99±0.6) and (99±0.2) reduction was seen for E.coli, MRSA and C. albicans respectively. Conclusion: Anatase 21 nm TiO2 nanoparticles show enhanced antimicrobial activity against the tested microbial strains following photoactivation by sunlight. Antimicrobial activity against three different types of microbial strains has varying effects