On-site detection of tobramycin using low-cost and ultrasensitive ratiometric fluorescence sensing platforms based on S,N-co-doped dual emission carbon quantum dots.

Authors

Chumeng Wang, Yuning Chen, Nengsheng Ye, Lu Zhang, Yuhong Xiang

Published in

Analytica chimica acta. Volume 1422. Pages 346068. Nov 08, 2026. Epub Aug 03, 2026.

Abstract

Tobramycin (TOB) is widely used in livestock and aquaculture, but its excessive use leads to residues in animal-derived foods and the environment, threatening human health. Rapid on-site detection methods are urgently needed to ensure food safety and environmental surveillance.
We synthesized sulfur and nitrogen co-doped dual-emission carbon quantum dots (S,N-CQDs) with emission at 340 nm (carbon core) and 620 nm (surface state). A polyadenine-extended TOB aptamer selectively quenched the 620 nm emission via electrostatic interaction-induced aggregation, while the 340 nm emission served as stable internal reference. Upon TOB addition, specific aptamer-target binding restored the 620 nm fluorescence, enabling ratiometric detection. Smartphone based dual and single-light-source portable platforms were further developed for visual on-site detection via RGB analysis. The three methods exhibited linear ranges of 10.0 nM-1.0 μM, detection limits of 2.14, 8.02, and 4.87 nM, and recoveries of 95.2%-99.4% in spiked milk and river water.
This work presents an integrated "detection-visualization" strategy combining a ratiometric fluorescence aptasensor with smartphone-based portable platforms. The method offers several distinct advantages: (1) the ratiometric design with built-in self-calibration ensures reliable detection in complex matrices; (2) the portable platforms enable rapid, user-friendly, and equipment-free on-site analysis; (3) the entire sensing system is cost-effective and does not require sophisticated instrumentation. These features make our approach a promising tool for routine monitoring of antibiotic residues in food safety and environmental protection.

PMID:
42763140
Bibliographic data and abstract were imported from PubMed on 20 Sep 2026.

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