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<p>Bacterial contamination poses significant threats to public health through food safety issues, creating a critical need for rapid and sensitive bacterial detection platforms. Herein, we developed a novel label-free fluorescent detection system leveraging target-triggered hybridization chain reaction (HCR) amplification, using <i>Escherichia coli</i> (<i>E. coli</i>) as a proof of concept. We engineered a hairpin-structured capture probe integrating an <i>E. coli</i>-specific aptamer with an HCR trigger sequence, achieving fluorescence amplification through three synergistic mechanisms: (1) HCR-driven DNA duplex assembly; (2) enhanced SYBR Green I (SG-I, a cost-effective non-labeled dye) intercalation into HCR-generated DNA duplexes; and (3) target-selective fluorescence modulation via MnO<sub>2</sub> nanosheets that quench background fluorescence through preferential adsorption of single-stranded DNA (ssDNA)-bound SG-I over duplex DNA-intercalated dye, exploiting the differential binding affinity of MnO<sub>2</sub> for ssDNA versus double-stranded DNA. This strategy enabled a fluorescence sensor with high sensitivity (detection limit: 17&#xa0;CFU/mL), excellent specificity, and broad dynamic range (5.0 × 10<sup>1</sup> ~ 5.0 × 10<sup>7</sup>&#xa0;CFU/mL), demonstrating robust performance in complex food matrices through successful <i>E. coli</i> detection in spiked milk and lettuce samples with recoveries of 98.81 to 104.26%, thereby underscoring the method’s reliability and practical utility for on-site food safety monitoring in real-world scenarios.</p> Graphical abstract <p></p>

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Target-triggered hybrid chain amplified fluorescence aptasensor based on label-free dye and MnO2 nanosheets system for Escherichia coli detection

  • 期刊论文

  • 发表日期：

    2025年5月28日

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  • Hao Liang,
  • Danliang Li,
  • Shiyu Jia,
  • Xuebing Zhang,
  • Qinqin Bai,
  • Ziyi Wang,
  • Yujiao Cai,
  • Jian Liu,
  • Lili Chen

摘要

Bacterial contamination poses significant threats to public health through food safety issues, creating a critical need for rapid and sensitive bacterial detection platforms. Herein, we developed a novel label-free fluorescent detection system leveraging target-triggered hybridization chain reaction (HCR) amplification, using Escherichia coli (E. coli) as a proof of concept. We engineered a hairpin-structured capture probe integrating an E. coli-specific aptamer with an HCR trigger sequence, achieving fluorescence amplification through three synergistic mechanisms: (1) HCR-driven DNA duplex assembly; (2) enhanced SYBR Green I (SG-I, a cost-effective non-labeled dye) intercalation into HCR-generated DNA duplexes; and (3) target-selective fluorescence modulation via MnO2 nanosheets that quench background fluorescence through preferential adsorption of single-stranded DNA (ssDNA)-bound SG-I over duplex DNA-intercalated dye, exploiting the differential binding affinity of MnO2 for ssDNA versus double-stranded DNA. This strategy enabled a fluorescence sensor with high sensitivity (detection limit: 17 CFU/mL), excellent specificity, and broad dynamic range (5.0 × 101 ~ 5.0 × 107 CFU/mL), demonstrating robust performance in complex food matrices through successful E. coli detection in spiked milk and lettuce samples with recoveries of 98.81 to 104.26%, thereby underscoring the method’s reliability and practical utility for on-site food safety monitoring in real-world scenarios.

Graphical abstract