title: DNA-based hybridization chain reaction and biotin-streptavidin signal amplification for sensitive detection of Escherichia coli O157:H7 through ELISA.
abstract: This study reported on a novel sandwich enzyme linked immunosorbent assay (ELISA) for the sensitive determination of Escherichia coli O157:H7 (E. coli O157:H7) by using DNA-based hybridization chain reaction (HCR) and biotin-streptavidin signal amplification. The anti-E. coli O157:H7 polyclonal antibody (pAb) was immobilized in the ELISA wells. The anti-E. coli O157:H7 monoclonal antibody (mAb) and initiator strand (DNA1) were labeled on gold nanoparticle (AuNP) to form a mAb-AuNP-DNA1 complex. In the presence of the target E. coli O157:H7, the sandwiched immunocomplex, which is pAb-E. coli O157:H7-mAb-AuNP-DNA1, could be formed. Two types of biotinylated hairpin were subsequently added in the ELISA well. A nicked double-stranded DNA (dsDNA) that contained abundant biotins was formed after HCR. Detection was performed after adding horseradish peroxidase-streptavidin and substrate/chromogen solution. Under optimal conditions, E. coli O157:H7 could be detected in the range of 5×10(2) CFU/mL to 1×10(7) CFU/mL; the limit of detection was 1.08×10(2) CFU/mL in pure culture. The LOD of the novel ELISA was 185 times lower than that of traditional ELISA. The proposed method is considerably specific and can be applied in the detection of whole milk samples inoculated with E. coli O157:H7. The coefficient of variation of in pure culture and in whole milk was 0.99-5.88% and 0.76-5.38%, respectively. This method offers a promising application in the detection of low concentrations of food-borne pathogens.
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors: Qi
authors: Q
authors: Guo
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors: Jiao-Jiao
authors: JJ
authors: Han
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors: Shan
authors: S
authors: Shan
authors: Jiangxi Province Center for Disease Control and Prevention, Nanchang 330096, China.
authors: Dao-Feng
authors: DF
authors: Liu
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors: Song-Song
authors: SS
authors: Wu
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors: Yong-Hua
authors: YH
authors: Xiong
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China. Electronic address: talktolaiwh@163.com.
authors: Wei-Hua
authors: WH
authors: Lai
mesh_terms: D001710:Biotin / Q000737:chemistry*; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli; D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification*; D007118:Immunoassay / Q000295:instrumentation; D017404:In Situ Hybridization, Fluorescence / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019809:Streptavidin / Q000737:chemistry*
chemical_list: D004269:DNA, Bacterial; D001710:Biotin; D019809:Streptavidin
keywords: Escherichia coli O157:H7; Hybridization chain reaction; Signal amplification