Antimicrobial activity of delaminated aminopropyl functionalized magnesium phyllosilicates

In this study, dispersed aminopropyl functionalized magnesium phyllosilicates (AMP clay) were tested for antimicrobial activity against various Gram negative and Gram positive bacteria including multidrug resistant bacterial strains and fungi. The AMP clay strongly inhibits the growth of microorganisms such as Escherichia coli, Staphylococcus aureus and Candida albicans. The inhibition of microbial growth by AMP clay is attributed to the amino propyl groups and their charge interactions. The bactericidal effect of AMP clay occurred within 1 h, and 95% killing was observed within 2 h. In addition, AMP clay could kill microbes by disrupting membrane integrity and thus essential components inside the cells. This effect was also evaluated through membrane depolarization assays and measured by the release of intracellular enzymes. The assessment of cell damage by the AMP clay was obtained by scanning electron microscopy (SEM) observation. Moreover, AMP clay activity was stably maintained after a long storage time of up to 30 days at different temperature conditions. The goals of this study were to synthesize the dispersed AMP clay from a commercially available substrate, which can be applied to various biomedical applications and environmental protection.