Antibiofilm property of green synthesized iron oxide nanoparticles from neem leaves

The production of nanoparticles usually utilizes a large quantity of organic solvents, toxic chemicals and non-biodegradable stabilizing agents. Recent research has focused on the production of nanoparticles using green, sustainable and more biodegradable technology. The use of green synthesized IONPs should reduce environmental impact of the production of nanoparticles besides being potentially attractive for invasive applications. S. aureus is known to be resistant to multiple types of drugs due to the bacteria’s ability to form a biofilm. This study aims to investigate the antibiofilm activity of green synthesized IONPs extracted from neem leaves (Azadirachta indica) on the S. aureus bacteria. Insights into the cellular interactions and the cellular changes due to exposure towards the IONPs and the bacteria were observed and recorded. Firstly, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using a microdilution broth method. The antibiofilm activity of IONPs was then evaluated using a minimum biofilm inhibitory concentration (MBIC) assay. The morphology of the S. aureus biofilm after the treatment with MBIC₉₀ of IONPs was observed under a scanning electron microscope (SEM). From this study, green synthesized IONPs showed antibacterial activity with an MIC at 6.25 mg/ml and an MBC value at 25 mg/ml. The antibiofilm activity of IONPs displayed a dose-dependent pattern with MBIC₅₀ and MBIC₉₀, which were at 1.56 mg/ml and 12.5 mg/ml, respectively (P<0.05). The SEM image of the sample treated with IONPs at MBIC₉₀ showed significantly reduced biofilm formation and an abnormal morphology of the S. aureus was also observed, indicating good antibiofilm action. These findings suggest that the green synthesized IONPs have potential as an antibiofilm agent especially against the S. aureus bacteria and may prove useful in the future as an eco-friendly alternative in the fight against S. aureus infections.