Covalent Organic Framework Nanosheets as an Enhancer for Light-Responsive Oxidase-like Nanozymes: Multifunctional Applications in Colorimetric Sensing, Antibiotic Degradation, and Antibacterial Agents
A. Santhana Krishna Kumar, Wei‐Bin Tseng, Wei‐Bin Tseng, Emmanuvel Arputharaj, Po‐Jung Jimmy Huang, Wei‐Lung Tseng, Wei‐Lung Tseng, Tomasz Bajda
Abstract
We herein fabricated poly(ethyleneimine)-stabilized covalent organic framework nanosheets (PEI-COF NSs) via hydrothermal treatment and showed their roles in enhancing light-responsive oxidase-like activity; the interaction of citrate-capped gold nanoparticles (C-AuNPs) with PEI-COF NSs, named as PEI-COF NSs@C-AuNPs, results in an increased contact with dissolved O 2 due to large surface and porosity of PEI-COF NSs and abundant amino functional groups on their planar surface. As a result of these features, the conversion of dissolved oxygen into superoxide anions and hydroxyl radicals under visible light can also be effectively catalyzed. Thus, PEI-COF NSs@C-AuNPs under visible light can catalyze more efficiently than C-AuNPs. Subsequently, the surface modification of PEI-COF NSs@C-AuNPs with thiolate polyethylene glycol-functionalized folic acid allowed the colorimetric sensing of folic acid receptor-overexpressed MCF-7 cells with a limit of detection of 30 cells/mL. Successively, the treatment of PEI-COF NSs@C-AuNPs with NaBH 4 produces more surface defects, providing almost complete photodegradation of tetracycline and ciprofloxacin. In addition, the citrate-capped silver nanoparticles (C-AgNPs) decorated with PEI-COF NSs (named PEI-COF NSs@C-AgNPs) showed excellent antibacterial activity against Escherichia coli and Staphylococcus aureus cells with 17 and 34 ng/mL minimum inhibitory concentrations and 2.1 and 1.8 g/mL inhibition zone diameters, respectively, under visible light; the bactericidal mechanism of PEI-COF NSs@C-AgNPs was further investigated using electron microscopy-related techniques.