G-triplex/hemin DNAzyme mediated colorimetric aptasensor for Escherichia coli O157:H7 detection based on exonuclease III-assisted amplification and aptamers-functionalized magnetic beads

• Published in: Talanta (Oxford) Vol. 269; p. 125457
• Main Authors: Pang, Lidong, Wang, Ling'e, Liang, Yaqi, Wang, Zhenghui, Zhang, Wei, Zhao, Qianyu, Yang, Xinyan, Jiang, Yujun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2024
• Subjects: Aptamers-functionalized magnetic beads; Colorimetric aptasensor; Escherichia coli O157; Exonuclease III-Assisted amplification; G-triplex/hemin; Colorimetric aptasensor; Aptamers-functionalized magnetic beads; G-triplex/hemin; Exonuclease III-Assisted amplification; Escherichia coli O157; H7
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2023.125457

Escherichia coli O157: H7 (E. coli O157: H7) is one of the most common foodborne pathogens and is widespread in food and the environment. Thus, it is significant for rapidly detecting E. coli O157: H7. In this study, a colorimetric aptasensor based on aptamer-functionalized magnetic beads, exonuclease III (Exo III), and G-triplex/hemin was proposed for the detection of E. coli O157: H7. The functional hairpin HP was designed in the system, which includes two parts of a stem containing the G-triplex sequence and a tail complementary to cDNA. E. coli O157: H7 competed to bind the aptamer (Apt) in the Apt-cDNA complex to obtain cDNA. The cDNA then bound to the tail of HP to trigger Exo III digestion and release the single-stranded DNA containing the G-triplex sequence. G-triplex/hemin DNAzyme could catalyze TMB to produce visible color changes and detectable absorbance signals in the presence of H2O2. Based on the optimal conditions, E. coli O157: H7 could be detected down to 1.3 × 103 CFU/mL, with a wide linear range from 1.3 × 103 to 1.3 × 107 CFU/mL. This method had a distinguished ability to non-target bacteria, which showed good specificity. In addition, the system was successfully applied to detect E. coli O157: H7 in milk samples. [Display omitted] •A simple and universal colorimetric aptasensor was constructed.•G-Triplex/hemin DNAzyme was used to catalyze the color change produced by TMB-H2O2.•The aptasensor based on EXO III-assisted had good specificity and sensitivity.•This protocol successfully detected E. coli O157:H7 in contaminated milk samples.