Dual-mode sensing by cobalt oxyhydroxide nanosheet for antibiotics

Abstract

Here, we present a cobalt oxyhydroxide (CoOOH) nanosheet-driven dual-mode sensor for fluoroquinolone antibiotics detection using fluorescence and colorimetric strategies. By using the intrinsic oxidizing ability of CoOOH nanosheets, 3,3′,5,5′ tetramethylbenzidine (TMB) was directly oxidized, causing its blue product (oxTMB) enabling sensitive and se-lective detection. A fluorescence quenching effect was observed owing to the inner filter effects, showing a noticeable change in blue coloration through interaction with fluoroquinolones (ofloxacin, norfloxacin, and ciprofloxacin). The sys-tem exhibited excellent sensitivity with linear responses in the range of 0–250 nM with the lowest detection limit of 2.23 nM, 19.31 nM, and 29.03 nM for ofloxacin, norfloxacin, and ciprofloxacin, respectively, outperforming many existing sen-sors. These findings formulate a fresh scheme for fluorescence and colorimetric analysis of Antibiotics in water. Fur-thermore, a cost-effective, mobile-device-assisted paper-based sensing system was developed for quick and visual field-level detection of fluoroquinolones. These sensors provide a practical and user-friendly tool for rapid antibiotic screen-ing, which can be completed within minutes. The proposed system offers a promising strategy for environmental and pharmaceutical monitoring, using CoOOH nanosheets as a versatile component in sensor development.