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<p>Rapid and accurate detection of pathogenic bacteria is critical for healthcare, food safety, and environmental monitoring. Here, we report a carbon dot-based fluorescent biosensor, prepared by a hydrothermal method, for sensitive and selective detection of <i>Escherichia coli</i> DNA. The carbon dots were characterized using field-emission scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy, confirming their uniform nanoscale morphology, structural integrity, and surface functionality. An amino-modified NH<sub>2</sub>-BL21 DNA probe enabled specific hybridization with the target sequence, producing quantifiable fluorescence changes. The biosensor exhibited a linear detection range of 50–250 fM, a limit of detection of 38.36 fM, recoveries of 87.06–113.57%, and stable performance over four weeks, with minimal cross-reactivity toward non-target sequences. Moreover, the carbon dot-based biosensor accurately detected <i>E. coli</i> DNA in drinking water and tap water, with recoveries of 95–126 and 93–119%, respectively, for concentrations of 75–225 fM. Lake water recoveries ranged from 68 to 119% at low concentrations, indicating minor matrix effects. Unlike most previously reported carbon dot-based sensing strategies, which rely on enzymatic amplification or labeling, this work demonstrates an amplification-free and label-free fluorescence detection strategy that achieves femtomolar sensitivity through direct probe-target hybridization. The simple fabrication procedure, high repeatability, and robust analytical performance underscore the potential of this platform for the rapid, reliable, and cost-effective detection of <i>Escherichia coli</i> DNA. These findings highlight the promise of carbon dot-based fluorescent biosensors as practical tools for point-of-care diagnostics, environmental surveillance, and food safety monitoring.</p>

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Fluorescent carbon dot-based biosensor for the rapid and sensitive detection of Escherichia coli DNA

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月29日

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  • Chau Nguyen Minh Hoang,
  • Son Hai Nguyen,
  • Michael Kraft,
  • Mai Thi Tran

摘要

Rapid and accurate detection of pathogenic bacteria is critical for healthcare, food safety, and environmental monitoring. Here, we report a carbon dot-based fluorescent biosensor, prepared by a hydrothermal method, for sensitive and selective detection of Escherichia coli DNA. The carbon dots were characterized using field-emission scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy, confirming their uniform nanoscale morphology, structural integrity, and surface functionality. An amino-modified NH2-BL21 DNA probe enabled specific hybridization with the target sequence, producing quantifiable fluorescence changes. The biosensor exhibited a linear detection range of 50–250 fM, a limit of detection of 38.36 fM, recoveries of 87.06–113.57%, and stable performance over four weeks, with minimal cross-reactivity toward non-target sequences. Moreover, the carbon dot-based biosensor accurately detected E. coli DNA in drinking water and tap water, with recoveries of 95–126 and 93–119%, respectively, for concentrations of 75–225 fM. Lake water recoveries ranged from 68 to 119% at low concentrations, indicating minor matrix effects. Unlike most previously reported carbon dot-based sensing strategies, which rely on enzymatic amplification or labeling, this work demonstrates an amplification-free and label-free fluorescence detection strategy that achieves femtomolar sensitivity through direct probe-target hybridization. The simple fabrication procedure, high repeatability, and robust analytical performance underscore the potential of this platform for the rapid, reliable, and cost-effective detection of Escherichia coli DNA. These findings highlight the promise of carbon dot-based fluorescent biosensors as practical tools for point-of-care diagnostics, environmental surveillance, and food safety monitoring.