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<p>Controlling <i>Salmonella</i> contamination throughout the food supply chain is critical for ensuring food safety and protecting public health. Despite recent advancements, alternative detection methods are still needed to mitigate the impact of <i>Salmonella</i> and improve its monitoring in complex food matrices. In this study, we present a simple and cost-effective approach for the preliminary detection of <i>Salmonella</i> in liquid foods such as milk and carrot juice. Gold nanoparticles (AuNPs) were synthesized and functionalized by physical adsorption of a specific anti-<i>Salmonella</i> aptamer onto their surface. For detection, aptamer-functionalized AuNPs were incubated with serial dilutions of <i>Salmonella</i> in buffer, milk, and carrot juice samples, and colorimetric changes were recorded visually and by Ultraviolet-visible spectroscopy. The results were compared with those obtained by standard polymerase chain reaction (PCR) and culture methods. Optimal aptamer adsorption was achieved in 0.01&#xa0;M MES buffer containing 200 mM NaCl at pH 5.8. Transmission electron microscopy characterization demonstrated that the functionalized AuNPs were stable against salt-induced aggregation and maintained good dispersion. The zeta potential increased to − 27 mV, indicating successful aptamer stabilization on the AuNP surface. The aptamer-functionalized AuNPs were evaluated as plasmonic aptasensors for <i>Salmonella</i> detection in both buffer and real food samples. The sensor exhibited a sensitivity of 400 CFU/mL with a linear detection range from 10³ to 10⁷ CFU/mL. High specificity was observed, with a 5-fold greater response to <i>Salmonella</i> compared to other tested bacteria, including <i>Escherichia coli</i>,<i> Staphylococcus aureus</i>,<i> Bacillus cereus</i>,<i> Citrobacter freundii</i>,<i> and Proteus mirabilis.</i> In field samples, the aptasensor demonstrated promising sensitivity, specificity, and accuracy, ranking third after PCR and cell culture methods. Future work should focus on optimizing sensor performance and sample preparation to enhance detection in complex food matrices and enable multiplex pathogen detection.</p>

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Detection of Salmonella contamination in milk and fruit juice with aptasensors based on the surface plasmon resonance of gold nanoparticles

  • 期刊论文

  • 发表日期：

    2025年9月8日

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  • Abbas Najafpour Khadem,
  • Behrouz Akbari-Adergani,
  • Ehsan Shokri,
  • Mahdi Rahaie,
  • Gholamhassan Asadi

摘要

Controlling Salmonella contamination throughout the food supply chain is critical for ensuring food safety and protecting public health. Despite recent advancements, alternative detection methods are still needed to mitigate the impact of Salmonella and improve its monitoring in complex food matrices. In this study, we present a simple and cost-effective approach for the preliminary detection of Salmonella in liquid foods such as milk and carrot juice. Gold nanoparticles (AuNPs) were synthesized and functionalized by physical adsorption of a specific anti-Salmonella aptamer onto their surface. For detection, aptamer-functionalized AuNPs were incubated with serial dilutions of Salmonella in buffer, milk, and carrot juice samples, and colorimetric changes were recorded visually and by Ultraviolet-visible spectroscopy. The results were compared with those obtained by standard polymerase chain reaction (PCR) and culture methods. Optimal aptamer adsorption was achieved in 0.01 M MES buffer containing 200 mM NaCl at pH 5.8. Transmission electron microscopy characterization demonstrated that the functionalized AuNPs were stable against salt-induced aggregation and maintained good dispersion. The zeta potential increased to − 27 mV, indicating successful aptamer stabilization on the AuNP surface. The aptamer-functionalized AuNPs were evaluated as plasmonic aptasensors for Salmonella detection in both buffer and real food samples. The sensor exhibited a sensitivity of 400 CFU/mL with a linear detection range from 10³ to 10⁷ CFU/mL. High specificity was observed, with a 5-fold greater response to Salmonella compared to other tested bacteria, including Escherichia coli, Staphylococcus aureus, Bacillus cereus, Citrobacter freundii, and Proteus mirabilis. In field samples, the aptasensor demonstrated promising sensitivity, specificity, and accuracy, ranking third after PCR and cell culture methods. Future work should focus on optimizing sensor performance and sample preparation to enhance detection in complex food matrices and enable multiplex pathogen detection.