Zirconium-Coated -Cyclodextrin Nanomaterials for Biofilm Eradication

Under alkaline treatment, zirconyl chloride (ZrOCl2.8H(2)O) became a zirconia gel and formed a stable complex with beta-cyclodextrin (beta CD). This complex was highly active in reactive oxygen species (ROS) formation via H2O2 decomposition. Its surface with numerous hydroxyl groups acts as an ionic sponge to capture the charged reaction intermediates, including superoxide (O-2(-center dot)) and the hydroxyl radical ((OH)-O-center dot). ROS, especially (OH)-O-center dot radicals, are harmful to living microorganisms because of their kinetic instability, high oxidation potential, and chemical nonselectivity. Therefore, (OH)-O-center dot radicals can engage in fast reactions with virtually any adjacent biomolecule. With H2O2, 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-beta CD-H2O2 also eradicated more than 99% of the biofilm of these four pathogens. Considering the difficult acquisition of resistance to the oxidation of (OH)-O-center dot, the results suggested that this beta CD-based nanomaterial might be a promising agent to target both drug-resistant pathogens with no cytotoxicity and exceptional antimicrobial activity.