Antibacterial activity of the micro and nanostructures of the optical material tris(8-hydroxyquinoline)aluminum and its application as an antimicrobial coating

Abstract

Although tris(8-hydroxyquinoline)aluminum (Alq₃), a fluorescent optical organometallic material, is known for its applications in optoelectronics, it has only few and limited applications in the biological field. In this study, the antibacterial activity of Alq₃ micro and nanostructures was investigated. We prepared Alq₃ nanostructures. We prepared nanosized Alq₃ as rice-like structures that assembled into flower shapes with an α-crystal phase. Then, Alq₃ micro and nanostructure antibacterial activities were estimated against seven human pathogenic bacterial strains. Besides, we compared their antibacterial activities with those of standard antibiotics. The minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and IC50 were evaluated. Alq₃ micro and nanostructure antibacterial activity showed considerable values compared to standard antibiotics. Besides, the obtained data revealed that the antibacterial activity of Alq₃ in nanostructures with a new morphology is more than that in microstructures. The antibacterial activity of Alq₃ nanostructures was attributed to their more surface interactions with the bacterial cell wall. The molecules of 8-hydroxyquinoline in the Alq₃ structure could play crucial roles in its antibacterial activity. To apply the achieved results, Alq₃ was incorporated with polystyrene (PS) in a ratio of 2% to fabricate a PS/Alq₃ composite and used to coat glass beakers, which showed inhibition in the bacterial growth reduced to 65% compared with non-coated beakers. The finding of this study showed that Alq₃ could be used as a promising antimicrobial coating.