Abstract
This paper presents a functional nanoparticle-enhanced enzyme-linked immunosorbent assay (FNP-ELISA) for detection of enterohemorrhagic Escherichia coli (EHEC) O157:H7. Immunomagnetic nanoparticles (IMMPs) conjugated with monoclonal anti-O157:H7 antibody were used to capture E. coli O157:H7. Beacon gold nanoparticles (B-GNPs) coated with polyclonal anti-O157:H7 and biotin single-stranded DNA (B-DNA) were then subjective to immunoreaction with E. coli O157:H7, which was followed by streptavidin-horseradish peroxidase (Strep-HRP) conjugated with B-GNPs based on a biotin-avidin system. The solutions containing E. coli O157:H7, IMMPs, B-GNPs, and Strep-HRP were collected for detecting color change. The signal was significantly amplified with detection limits of 68 CFU mL-1 in PBS and 6.8 × 102 to 6.8 × 103 CFU mL-1 in the food samples. The FNP-ELISA method developed in this study was two orders of magnitude more sensitive than immunomagnetic separation ELISA (IMS-ELISA) and four orders of magnitude more sensitive than C-ELISA. The entire detection process of E. coli O157:H7 lasted only 3 h, and thus FNP-ELISA is considered as a time-saving method.
Highlights
The World Health Organization estimated that about 1.8 million people worldwide die every year from diarrheal diseases, which are often caused by consuming microbiologically contaminated food or by drinking water [1]
We developed a functional nanoparticleenhanced Enzyme-linked immunosorbent assay (ELISA) (FNP-ELISA) using immunomagnetic nanoparticles (IMMPs) and beacon gold nanoparticles (B-GNPs) for detecting E. coli O157:H7
Properties of IMMS We prepared Magnetic nanoparticles (MPs) that were roughly spherical in shape with diameters ranging from 40–60 nm, and contained an finding was supported by a previous study, which showed that target cells can be separated from samples using MPs coupled with aptamer/nucleic acid/antibody [45,46]
Summary
The World Health Organization estimated that about 1.8 million people worldwide die every year from diarrheal diseases, which are often caused by consuming microbiologically contaminated food or by drinking water [1]. Among the pathogens causing diarrheal diseases, enterohemorrhagic Escherichia coli (EHEC) strains are prominently responsible for serious foodborne outbreaks [2,3]. E. coli O157:H7, a predominant strain of EHEC that was first isolated and recognized as a new type of intestinal pathogenic bacterium in the United States in 1982 [4], has become a global public health problem. The development of a rapid and reliable detection of E. coli O157:H7 has become highly important for food safety and public health [6]. Some very sensitive and selective but expensive, complicated, and time-consuming methods have been applied in the detection of E. coli O157:H7, especially including immunomagnetic separation (IMS) analysis [13], flow cytometry [14], fluorescence in situ hybridization [15], DNA microarrays [16], and several label-free methods (such as surface plasmon resonance [17] and use of electrochemical impedance immunosensors [18,19])
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