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<p> A highly sensitive and specific immunoassay for the detection of <i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Typhimurium (<i>S.</i> Typhimurium)&#xa0;is presented, which integrates aptamer recognition with a DNA walker-based signal amplification strategy. Target bacteria are first captured by plate-immobilized antibodies and then specifically bound by an aptamer. Free unbound aptamer in the supernatant is harvested and sequesters a small fraction of initiator DNA, leaving most available for hybridization with, fluorescein-labeled thiolated DNA (SH-DNA-FAM). The initiator DNA/SH-DNA-FAM duplex then recruits the nicking endonuclease Nb.BbvCI, which cleaves the SH-DNA-FAM and releases the fluorophore from the AuNP-mediated quenching state. The liberated initiator DNA is recycled to drive successive cleavage events, resulting in a robust DNA walker amplification cascade and a strongly enhanced fluorescence signal. This method achieves a detection limit of 43 CFU/mL with a linear range of 10<sup>2</sup>–10<sup>6</sup> CFU/mL (R<sup>2</sup> = 0.98). Moreover, it not only displays excellent specificity but also enables rapid signal amplification, demonstrating considerable potential for food-safety monitoring.</p> Graphical Abstract <p></p>

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Sensitive detection of Salmonella enterica subsp. enterica serovar typhimurium based on antibody-aptamer dual recognition and DNA walker signal amplification

  • 期刊论文

  • 发表日期：

    2026年4月15日

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  • Wenjia Yan,
  • Jiahui Wang,
  • Liangying Cao,
  • Jiao Hu,
  • Chaohui Chen

摘要

A highly sensitive and specific immunoassay for the detection of Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) is presented, which integrates aptamer recognition with a DNA walker-based signal amplification strategy. Target bacteria are first captured by plate-immobilized antibodies and then specifically bound by an aptamer. Free unbound aptamer in the supernatant is harvested and sequesters a small fraction of initiator DNA, leaving most available for hybridization with, fluorescein-labeled thiolated DNA (SH-DNA-FAM). The initiator DNA/SH-DNA-FAM duplex then recruits the nicking endonuclease Nb.BbvCI, which cleaves the SH-DNA-FAM and releases the fluorophore from the AuNP-mediated quenching state. The liberated initiator DNA is recycled to drive successive cleavage events, resulting in a robust DNA walker amplification cascade and a strongly enhanced fluorescence signal. This method achieves a detection limit of 43 CFU/mL with a linear range of 102–106 CFU/mL (R2 = 0.98). Moreover, it not only displays excellent specificity but also enables rapid signal amplification, demonstrating considerable potential for food-safety monitoring.

Graphical Abstract