Colorimetric DNAzyme Biosensor for Convenience Detection of Enterotoxin B Harboring <i>Staphylococcus aureus</i> from Food Samples

In the present study, a colorimetric DNAzymes biosensor strategy was devised in combination with immunomagnetic separation for rapid and easy detection of enterotoxin B harboring <i>Staphylococcus aureus</i> from food and clinical samples. The method employs immunocapture of <i>S. aureus</i> and amplification of <i>seb</i> gene by DNAzyme complementary sequence integrated forward primer and with specific reverse primer. The DNAzyme sequence integrated dsDNA PCR products when treated with hemin and TMB (3,3′,5,5′-tetramethylbenzidine) in the presence of H₂O₂ produce colorimetric signal. A linear relationship of optical signal with the initial template of <i>seb</i> was obtained which could be monitored by visually or spectrophotrometrically for qualitative and quantitative detection. The limit of detection for the assay was approximately 10² CFU/mL of <i>seb</i> gene harboring target. This method is convenient compared to gel based and ELISA systems. Further, spiking studies and analysis on natural samples emphasized the robustness and applicability of developed method. Altogether, the established assay could be a reliable alternative, low-cost, viable detection tool for the routine investigation of <i>seb</i> from food and clinical sources