Chemiluminescent aptasensor capable of rapidly quantifying Escherichia Coli O157:H7

•Development of biosensor using E. Coli O157:H7 aptamer instead of antibodies.•Biosensor capable of quantifying E. Coli O157:H7 without time-consuming procedures.•Cost-effective and rapid biosensor capable of trace-levels of E. Coli O157:H7.

Cost-effective and easy-to-use biosensor was developed for the rapid quantification and monitoring of Escherichia (E.) Coli O157:H7 in sample using E. Coli O157:H7 aptamer, graphene oxide (GO)/iron nanocomposites, and guanine chemiluminescence detection. E. Coli O157:H7 aptamer-conjugated 6-carboxyfluorescein (6-FAM) with excellent specificity captured E. Coli O157:H7 in a sample when the mixture was incubated for 1 h at 37 °C. Free E. Coli O157:H7 aptamers remaining in sample after the incubation were removed with GO/iron nanocomposites based on the principle of π–π stacking interaction between free aptamer and GO/iron nanocomposites. Then, E. Coli O157:H7 bound with aptamer-conjugated 6-FAM in sample emitted strong light when guanine chemiluminescent reagents (e.g., 3,4,5-trimethoxylphenylglyoxal hydrate, Tetra-n-propylammonium hydroxide) were added in the sample. The strength of light emitted in guanine chemiluminescence reaction was proportionally enhanced with the increase of E. Coli O157:H7 concentration. The limit of detection (LOD) of biosensor capable of quantifying E. Coli O157:H7 with good accuracy, precision, and reproducibility was as low as 4.5×103 cfu/ml. We expect that the rapid analytical system can be applied in the field of food safety as well as public health.

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