A Colorimetric Strategy Based on Aptamer-Catalyzed Hairpin Assembly for the On-Site Detection of <i>Salmonella typhimurium</i> in Milk
<i>Salmonella typhimurium</i> (<i>S. typhimurium</i>) is a foodborne pathogen that has caused numerous outbreaks worldwide, necessitating the development of on-site strategy to prevent early contamination. Here, we set up an enzyme-free strategy for aptamer-catalyzed hairpin...
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| Autores principales: | , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/fbe09687ed9747f1b327850290efed60 |
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| Sumario: | <i>Salmonella typhimurium</i> (<i>S. typhimurium</i>) is a foodborne pathogen that has caused numerous outbreaks worldwide, necessitating the development of on-site strategy to prevent early contamination. Here, we set up an enzyme-free strategy for aptamer-catalyzed hairpin assembly in which salt-induced aggregation of unmodified gold nanoparticles (AuNPs) served as a colorimetric signal output, allowing on-site detection of <i>S. typhimurium</i> in milk. The aptamer-functionalized magnetic beads were used as a vehicle of specifically enriching target bacteria which conjugated with target aptamer to trigger the “Y” shape catalytic hairpin assembly (Y-CHA) circuit. Due to the hairpins desorbing from the surface of AuNPs to the formation of a large amount of double-stranded DNA (dsDNA), AuNPs turned from dispersion to aggregation in the presence of <i>S. typhimurium</i>, resulting in a change of the colorimetric signal from red to blue-gray. The signal output showed a linear relationship for <i>S. typhimurium</i> over a concentration range of 10<sup>2</sup> to 10<sup>6</sup> CFU/mL, with a sensitivity of 2.4 × 10<sup>2</sup> CFU/mL under optimal conditions. The visual protocol has excellent selectivity even in the presence of other competitive bacteria and has been validated in real milk samples with a sensitivity of 2.8 × 10<sup>3</sup> CFU/mL. |
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