Development of AuNP-based biosensor as an alternative rapid and sensitive method for detection of Listeria monocytogenes

Abstract

Rapid, accurate, and field-deployable detection methods are essential to prevent outbreaks caused by Listeria monocytogenes (L. monocytogenes), a major foodborne pathogen associated with high morbidity and mortality rates. Conventional detection approaches, including PCR, VITEK-2, and MALDI-TOF/MS, although highly sensitive and specific, typically require 12–24 hours to yield results and depend on sophisticated instrumentation and trained personnel, thereby limiting their on-site applicability. In the present study, we developed a novel colorimetric biosensing platform based on oligonucleotide-functionalized gold nanoparticles (AuNPs) for the rapid, sensitive, and equipment-free detection of L. monocytogenes. A total of 200 dairy product samples were analyzed using selective culture media, biochemical assays, automated identification systems, molecular techniques, and the proposed AuNP–oligonucleotide probe biosensor. Of the nine presumptive L. monocytogenes isolates, six (66.7%) were confirmed by VITEK-2, MALDI-TOF, PCR, and AuNP-based biosensing. The developed AuNP biosensor demonstrated exceptional analytical performance, achieving a detection limit of 10 pg/µL and 100% specificity in discriminating L. monocytogenes from non-target bacterial species. The localized surface plasmon resonance (LSPR) response of the AuNPs exhibited a characteristic absorption peak within the 520–530 nm range, confirming successful target hybridization. This innovative AuNP-based optical biosensing system provides a rapid, accurate, and cost-effective alternative for L. monocytogenes detection, bridging the gap between conventional molecular diagnostics and field-based applications. The platform shows significant potential for integration into food safety surveillance programs and clinical diagnostic workflows.