Zirconium-Coated β-Cyclodextrin Nanomaterials for Biofilm Eradication.

Under alkaline treatment, zirconyl chloride (ZrOCl 2 .8H 2 O) became a zirconia gel and formed a stable complex with beta-cyclodextrin (βCD). This complex was highly active in reactive oxygen species (ROS) formation via H 2 O 2 decomposition. Its surface with numerous hydroxyl groups acts as an ionic sponge to capture the charged reaction intermediates, including superoxide (O 2 -• ) and the hydroxyl radical ( • OH). ROS, especially • OH radicals, are harmful to living microorganisms because of their kinetic instability, high oxidation potential, and chemical nonselectivity. Therefore, • OH radicals can engage in fast reactions with virtually any adjacent biomolecule. With H 2 O 2 , the complex with cationic and hydrophobic moieties interacted with the anionic bacterial membrane of two Gram-positive ( Staphylococcus aureus and S. epidermidis ) and two Gram-negative ( Escherichia coli and Klebsiella pneumoniae ) strains. The Zr-βCD-H 2 O 2 also eradicated more than 99% of the biofilm of these four pathogens. Considering the difficult acquisition of resistance to the oxidation of • OH, the results suggested that this βCD-based nanomaterial might be a promising agent to target both drug-resistant pathogens with no cytotoxicity and exceptional antimicrobial activity.