摘要
In this study,a colorimetric biosensor was developed based on the use of aptamer-functionalized magnetic beads and catalytic hairpin assembly(CHA),in conjunction with a three-way junction DNA(3WJ/DNA)and isolated Gquadruplex/hemin DNAzyme triple signal amplification.This approach enabled the label-free,visual and sensitive detection of Escherichia coli O157:H7.The target bacterium binds to the aptamer,which releases complementary DNA,thereby triggering the CHA to produce 3WJ/DNA.The three ends of 3WJ/DNA can each form a G-quadruplex/DNAzyme,thereby catalyzing the 3,3′,5,5′-tetramethylbenzidine(TMB)-H2O2 system to turn blue.Notably,we provide a triple signal amplification method of G-quadruplex/hemin DNAzyme based on the triple end of CHA-3WJ/DNA by cleverly screening and designing an isolated G-quadruplex,significantly improving the sensitivity.The proposed method’s limit of detection(LOD)was 8 CFU/mL,exhibiting good linearity within the range of 10°-10^(8) CFU/mL.Impressively,the method successfully detected E.coli O157:H7 in ultrahightemperature-sterilized,pasteurized and raw milk,exhibiting good stability and reproducibility.
基金
supported by the Joint Funds of the National Natural Science Foundation of China[No.U21A20272].
