Dual FITC lateral flow immunoassay for sensitive detection of Escherichia coli O157:H7 in food samples.
A pattern of signal amplification lateral flow immunoassay (LFIA) for pathogen detection, which used fluorescein isothiocyanate (FITC) labeled antigen and antibody for dual FITC-LFIA was developed. Escherichia coli O157:H7 (E.coli O157:H7) was selected as the model analyte. In the signal amplification LFIA method, FITC was mixed with sample culture medium, with the presence of E.coli O157:H7 in the samples, the bacteria could emit a yellow-green fluorescence after incubation, creating a fluorescent antigen probe. This antigen probe was added to LFIA, which already contained E.coli O157:H7 monoclonal antibodies-FITC (McAb-E.coli O157:H7-FITC) dispersed in the conjugate pad. Another E.coli O157:H7 McAb was the test line, and goat anti-mouse IgG antibody was the control line in nitrocellulose (NC) membrane. The visual limit of detection (LOD) of the strip for qualitative detection was 10(5) CFU/mL while the LOD for semi-quantitative detection could down to 10(4) CFU/mL by using scanning reader. Signal amplification LFIA was perfectly applied to the detection of food samples with E.coli O157:H7. The LOD was substantially improved to 1 CFU/mL of the original bacterial content after pre-incubation of the bread, milk and jelly samples in broth for 10, 8 and 8h respectively. The results of this method was more sensitive by 10-fold than the conventional colloidal gold (CG) based strips and comparable to the traditional ELISA. This simple, low-cost and easy to be popularized method served as a significant step towards the development of monitoring food-borne pathogens in food-safety testing.
School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Chunmei
C
Song
School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Jinxin
J
Liu
School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Jianwu
J
Li
School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address: liuq@usst.edu.cn.
Qing
Q
Liu
D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation; D015169:Colony Count, Microbial; D004867:Equipment Design; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D015200:Fluoroimmunoassay / Q000295:instrumentation*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008892:Milk / Q000382:microbiology
D055910:Antibodies, Immobilized; D000911:Antibodies, Monoclonal; D005456:Fluorescent Dyes; D016650:Fluorescein-5-isothiocyanate
Dual lateral flow immunoassay; Escherichia coli O157:H7; FITC; Signal amplification