Nanozymes for Detection of Foodborne Pathogens

Foodborne pathogens are bacteria, viruses, parasites, and some fungi that cause foodborne illness, mainly Escherichia coli, Listeria, Pseudomonas aeruginosa, Enterobacter sakazakii, Shigella, Salmonella and Norovirus. Food contamination caused by foodborne pathogens has attracted worldwide attention. Enzyme-linked immunosorbent assay (ELISA) is one of the most commonly used methods for the detection of such pollutants.

Using nanozymes instead of natural biological enzymes can effectively avoid the defects of biological enzyme application, improve the sensitivity, stability and efficiency, and reduce the cost. Creative Enzymes provides nanozymes and detailed protocols for detecting foodborne pathogens.

Analysis of Escherichia coli with Nanozyme

• Escherichia coli is a pathogenic bacterium that seriously endangers human health.
• Creative Enzymes develops lateral immunochromatography with Pd / Pt nanozyme-labeled antibody based on the sandwich of double antibodies. The Pd / Pt enzyme has excellent peroxisome-like activity and can efficiently catalyze the H₂O₂-TMB color reaction, significantly improving the sensitivity of the detection.
• Using the same double-antibody sandwich principle, we use Pt / Au nanozyme as an antibody marker to catalyze the oxidation of TMB by H₂O₂ for the visualization of E. coli by immunochromatography.

Fig. 1 Schematic principle of this novel multi-readout and label-free LFIA for E. coli detection. (Wang Z, et al., 2020)

• In addition, we prepare modified Prussian blue nanozyme. It is used as an H₂O₂-TMB color signal catalytic amplification probe and specific identification material to form a sandwich structure for visual analysis of E. coli. The detection methods described above are simple to operate and do not require pre-processing such as bacterial culture and nucleic acid extraction, enabling rapid on-site screening of pathogens.

Analysis of Listeria with Nanozyme

• Listeria monocytogenes is one of the most common and lethal foodborne pathogens, causing infections of the nervous and immune systems.

Fig. 2 Schematic representation for the preparation of Fe₃O₄ NPC (A), the principle of the Fe₃O₄ NP-based biosensor (B), and the Fe₃O₄ NPC catalyzed signal amplification biosensor (C). (Zhang L, et al., 2016)

• We design and prepare a Fe₃O₄ magnetic nanoparticle cluster (NPC) with peroxidase-like activity. The content of Listeria in the samples is determined by colorimetric sandwich assay using aptamers coupled with nanozymes. This method has high catalytic activity against H₂O₂-TMB and can be effectively used as a signal amplification probe to increase sensitivity and specificity.
• We also develop a colorimetric sensor based on Ag nanozymes to regulate the aggregation morphology of Au nanoparticles. Aptamer-modified magnetic beads and antibody-modified Ag enzymes were used to trap Listeria to form a sandwich structure. It is also combined with magnetic separation techniques to enable accurate determination of Listeria in samples.

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