Hierarchical Au Nanoflowers Formed in an Ionic Liquid/Water System for Bacterial Inhibition.

The waning potency of antibiotics against resilient bacterial strains highlights the imperative demand for nanomaterial approaches in addressing bacterial infections. However, the creation of a nanostructure in the post-antibiotic era has necessitated not only exceptional antibacterial activity but also high accessibility endowed with compatible natural molecules. By using a type of biomolecule-derived ionic liquid phases as the passivating ligands, we showcase a simple synthetic route to flower-shaped gold nanoparticles (AuNPs) of over 100 nm in diameter, which represent a class of large antibacterial nanostructures against both Gram-positive and Gram-negative bacteria. The hierarchical growth of the gold nanoflowers (AuNFs) achieved within minutes relies on the competition between individual domain particle growth and thermodynamic particle coalescence, which is thought to be driven by large reaction kinetics and nanoparticle passivation. Insights into the antibacterial activity reveal that the positively charged AuNFs with many protrusions cause enhanced membrane permeability and disruption of the bacterial membrane while boosting the level of intracellular reactive oxygen species (ROS). The minimum inhibitory concentration (MIC) of the AuNFs can be as low as 16 μg/mL, outperforming most of the reported AuNPs. Our findings present a general approach to hierarchical nanomaterials with antibacterial properties achievable without the need for a professional background, suggesting a potential solution to antibacterial resistance and reduced reliance on antibiotics. [ABSTRACT FROM AUTHOR]