Table 1.

Comparison of rapid detection methods for hazardous substances in foods and COVID-19.

Methods	COVID-19		Hazardous		Characteristics	Instruments	Mechanism
	Targets	Specimens	Targets	Samples
high-throughput sequencing (HTS)	DNA	Upper or lower respiratory tract	Foodborne pathogen, genetically modified composition, foodborne composition, etc.	Fermented food, meat products, etc.	No need to culture, no preference, can complete the detection of a variety of pathogens such as bacteria, fungi, viruses and parasites at one time	Sequencer	After the target RNA is made into a DNA library that can be identified and analysed by a sequencer, the simultaneous detection of millions of nucleic acid sequences can be achieved
Real-time fluorescent quantitative PCR (RT-PCR)	DNA complementary to RNA	Upper or lower respiratory tract	Foodborne pathogen, genetically modified composition, foodborne composition, etc.	Fermented food, meat products, etc.	Not time-consuming, many test samples, simple and fast result judgment, low test cost, need professional instruments and operators	UV analyser, electrophoretic instrument	The complementary DNA obtained by the target genome RNA restore is used as a template to amplify the nucleic acid sequence of the pathogen, and the intensity of the fluorescent dye and the product is successfully detected by the intensity of the fluorescent signal
Loop-mediated isothermal amplification (LAMP)	DNA complementary to RNA	Upper or lower respiratory tract	Foodborne pathogen, genetically modified composition, foodborne composition, etc.	Fermented food, meat products, etc.	Fast amplification, simple operation, simple detection, and intuitive judgment of detection results	Turbidity or visualization	Design specific primers for specific areas of the target gene, then use strand-displacement DNA polymerase, and keep it at constant temperature for 10 min to achieve nucleic acid amplification
Recombinase polymerase amplification (RPA)	DNA	Upper or lower respiratory tract	Foodborne pathogens, genetically modified crops, food microorganisms, etc.	Fermented food, meat products, etc.	Sensitive amplification is achieved at normal temperatures, no equipment is required, the limit is low	RPA analyser	After the recombinase is involved, the protein-DNA complex is formed, the DNA chain substituted by the strand displacement enzyme is bonded to the SSB protein, and the DNA chain extends with the template DNA double helix continuously restricted to achieve product amplification
Constant temperature amplification chip	RNA	Upper or lower respiratory tract	Food microorganisms	Fermented food, meat products, etc.	High sensitivity, strong specificity, no complicated sample processing, easy to miss the detection of rare pathogenic pathogens	Analyser	Nucleic acid amplification and nucleic acid extraction were performed using a chain shift DNA polymerase under constant temperature conditions, and perform corresponding labelling by means of fluorescein
Detection technology based on Cas enzyme	RNA	Upper or lower respiratory tract	–	–	Low-cost, accurate, time-saving but requires high specificity of crRNA target recognition	Fluorescence analyser	CRISPR RNA binded the target sequence while the nonspecific endonuclease activity of Cas13 or Cas12 started, which led to the cleavage of nearby reporter RNAs and generated the signal
Colloidal gold immunochromatography assay (GICA)	IgM, IgG, total antibody	Blood or serum samples	Pesticide residues, veterinary drug residues, hormones	Meat products, crops, etc.	Quick and easy, no special equipment is needed, no quantification, risk of exposure, low sensitivity, and easily interfered with by environmental factors	Colloidal immunoassial analyser or visualization	Based on the antigen–antibody specific immune response, colloidal gold particles are used as a tracer to mark one of them The marker is driven by solvent chromatography and immune response occurs on the C/T line
Enzyme linked immunosorbent assay (ELISA)	IgA, IgM, IgG, total antibody, plasma cytokines	Whole blood, serum or plasma	Veterinary drugs residue, antibiotic, pesticides residue, protein, offending drug, genetically modified, toxins, etc.	Meat products, crops, etc.	Highly sensitive and specific, many options for different determination and analysis, few requirements for reagents, the reproducibility of data is higher	Enzyme detection instrument or visualization	The principle of colour change occurs through the binding of antibodies and enzyme complexes while maintaining immunoactivity of antibodies
Fluorescence immunochromatography	Total antibody and IgM	Blood or serum sample	Foodborne pathogen, metals ions, pesticides/herbicides/metabolites residues, preservatives, protein, etc.	Fermented food, meat products, crops, water, etc.	High sensitivity, high resolution, wide detection range and low reagent cost	Fluorescence spectrophotometer	Use fluorescent substances as tracer markers to label specific antibodies (or antigens), and then combine with the antigens (or antibodies) to be tested, and detect the specific fluorescence reaction with a fluorescence detector
Electrochemical biosensor	Reactive oxygen species (ROS) in the sputum sample	Sputum	Foodborne pathogen, metals ions, pesticides/herbicides/metabolites residues, preservatives, protein, etc.	Fermented food, meat products, crops, water, etc.	Simple structure, convenient assembly, sensitive and accurate detection results	Visualization	Identifying the interaction of the target analyte and the biosensor to convert the chemical amount of the analyte to the electrical signal to achieve the monitoring of the target
Lateral flow immunoassay (LFIA)	IgM, IgG, total antibody	Blood or serum sample	Proteins, pathogens, toxins and antibiotics	Processing food, dairy products, etc.	Low sensitivity, material errors will affect the test results	Visualization	Based on a sandwich immunoassay that captures the target molecule and shows different signals (colours) on the test and control line using colloidal gold, carbon, or latex as commonly labels
Chest computed tomography (CT) scan	Virus-infected lung	Lung	–	–	Painless, non-invasive, requiring highly trained personnel and sophisticated instrumentation	Computed tomography scanner	The detection of the virus in a patient is based on identifying the possible abnormalities caused by the viral infection in the chest by cross sectional X-ray images taken from different angles