Immunofluorescent-aggregation assay based on anti-Salmonella typhimurium IgG-AuNCs, for rapid detection of Salmonella typhimurium

Sensitive and rapid detection of pathogenic bacteria plays an important role in avoiding food poisoning. However, the practical application value of conventional assays for detection of foodborne bacteria, are limited by major drawbacks; these include the laboriousness of pure culture preparation, complexity of DNA extraction for polymerase chain reaction, and low sensitivity of enzyme-linked immunosorbent assay. Herein, we designed a non-complex strategy for the sensitive, quantitative, and rapid detection of Salmonella typhimurium with high specificity, using an anti-Salmonella typhimurium IgG-AuNC-based immunofluorescent-aggregation assay. Salmonella typhimurium was agglutinated with fluorescent anti-Salmonella typhimurium IgG-AuNC on a glass slide, and observed using a fluorescence microscope with photoexcitation and photoemission at 560 nm and 620 nm, respectively. Under optimized reaction conditions, the AuNC-based immunofluorescent-aggregation assay had a determination range between 7.0 x 10(3) and 3.0 x 10(8) CFU/mL, a limit of detection of 1.0 x 10(3) CFU/mL and an assay response time of 3 min. The technique delivered good results in assessing real samples.

Automated summary

This study presents a non-complex strategy for sensitive, quantitative, and rapid detection of Salmonella typhimurium with high specificity. The method utilizes fluorescent anti-Salmonella typhimurium IgG-AuNC to agglutinate Salmonella typhimurium on a glass slide, which is then observed using a fluorescence microscope. Under optimized conditions, the assay has a wide determination range, low detection limit, and fast response time.