Establishment of indirect ELISA method for Salmonella antibody detection from ducks based on PagN protein

Machine learning supported single-stranded DNA sensor array for multiple foodborne pathogenic and spoilage bacteria identification in milk

Ensuring food safety through rapid and accurate detection of pathogenic bacteria in food products is a critical challenge in the food supply chain. In this study, a non-specific optical sensor array was proposed for the identification of multiple pathogenic bacteria in contaminated milk samples. Fluorescence-labeled single-stranded DNA was efficiently quenched by two-dimensional nanoparticles and subsequently recovered by foreign biomolecules. The recovered fluorescence generated a unique fingerprint for each bacterial species, enabling the sensor array to identify eight bacteria (pathogenic and spoilage) within a few hours. Four traditional machine learning models and two artificial neural networks were applied for classification. The neural network showed a 93.8 % accuracy with a 30-min incubation. Extending the incubation to 120 min increased the accuracy of the multiplayer perceptron to 98.4 %. This sensor array is a novel, low-cost, and high-accuracy approach for the identification of multiple bacteria, providing an alternative to plate counting and ELISA methods.

Dual-Functional Tetrahedron Multivalent Aptamer Assisted Amplification-Free CRISPR/Cas12a Assay for Sensitive Detection of Salmonella

Salmonellosis continues to impose a significant economic burden globally. Rapid and sensitive detection of Salmonella is crucial to preventing the outbreaks of foodborne illnesses, yet it remains a formidable challenge. Herein, a dual-functional tetrahedron multivalent aptamer assisted amplification-free CRISPR/Cas12a assay was developed for Salmonella detection. In the system, the aptamer was programmatically assembled on the tetrahedral DNA nanostructure to fabricate a multivalent aptamer (TDN-multiApt), which displayed a 3.5-fold enhanced avidity over the monovalent aptamer and possessed four CRISPR/Cas12a targeting fragments to amplify signal. Therefore, TDN-multiApt could directly activate Cas12a to achieve the second signal amplification without any nucleic acid amplification. By virtue of the synergism of high avidity and cascaded signal amplifications, the proposed method allowed the ultrasensitive detection of Salmonella as low as 7 cfu mL-1. Meanwhile, this novel platform also exhibited excellent specificity against target bacteria and performed well in the detection of various samples, indicating its potential application in real samples.