We demonstrate the green synthesis of enzyme mimic metal-bismuth oxyhalide nanomaterials at room temperature from an aqueous mixture of metal ions or metal nanoparticles, bismuth ions, and halide ions. The enzymatic activity of the bismuth oxyhalide nanomaterials can be regulated by doping with suitable metal such as Au, Ni, Mn or Zn. Depending of the metal doping the nanozymes exhibit different enzyme-like activities, such as oxidase and peroxidase-like activity. Aptamer-modified gold nanoparticles/bismuth oxychloride (Apt-Au NPs/BiOCl) nanocomposites, gold nanoparticles/bismuth oxyiodide (Au NPs/BiOI) nanocomposites, and nickel oxide nanoparticles/bismuth oxyiodide (NiO NPs/BiOI) nanocomposites exhibit peroxidase-like or oxidase-like activity for the catalytic conversion of Amplex Red (AR) to fluorescent resorufin. The catalytic activity of Apt-Au NPs/BiOCl nanocomposites is suppressed by vascular endothelial growth factor-A165 (VEGF-A165) molecules that specifically interact with the aptamer units (Del-5-1 and v7t-1) on the nanocomposite surface, which enables efficient detection of VEGF-A165 in biological samples. The AR/H2O2-Apt-Au NPs/BiOCl nanocomposites probe shows high selectivity (&gt;1000-fold over other proteins) and sensitivity (detection limit ~0.5 nM) for the detection of VEGF-A165. Similarly, some heavy metal ions also inhibit the enzyme-like activity of Au NPs/BiOI nanocomposites and NiO NPs/BiOI nanocomposites, which allows for the detection of Hg2+ and Pb2+ ions, respectively, down to nanomolar quantities. The practicality of these two nanozyme probes was validated by analysis of Hg2+ and Pb2+ ions in environmental water samples (tap water, river water, lake water, and sea water). In addition to sensing, the oxidase-like activity of Au/BiOI nanocomposites is effective in wide spectrum antimicrobial activity against E. coli, K. pneumoniae, S. enteritidis, S. aureus, B. subtilis, and methicillin-resistant S. aureus (MRSA). The bactericidal property of the Au/BiOI nanocomposite arose from the combined effect of the disruption of the bacterial membrane through a strong interaction of the nanocomposite with the bacteria and the generation of reactive oxygen species. Furthermore, intrastromal administration of Au/BiOI nanocomposites can effectively alleviate S. aureus-induced bacterial keratitis in rabbits, suggesting a significant disinfectant benefit in preclinical studies.

Enzyme-mimic metal-bismuth oxyhalide for sensing and antimicrobial applications

2019 Fall National Meeting

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