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

Abstract

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.