Research On Food Quality Detection Based On Metal Oxide Nano-biosensor

In recent years,food quality accidents frequently occur and cause serious health risks,and food quality and safety has been paid more and more attention by people,among which the detection of food chemical composition is a key link to control food quality and safety.Compared with most traditional methods which have long analysis cycle,large equipment and high detection cost at present,biosensors are widely concerned in the field of food safety detection because of their advantages such as short cycle,low cost,small size and portability,and diversity of detectable substances,how to develop sensitive elements with high sensitivity,high selectivity and strong anti-interference ability is the key problem of related research.Among them,the enzyme-free metal oxide nanomaterials are potential materials for the preparation of biosensor,which not only have similar catalytic properties to biological enzymes,but also have controllable morphology and excellent chemical and electrical properties.In this paper,three common small molecules involved in food safety detection,namely glucose,hydrogen peroxide（H₂O₂）and triethylamine,are studied from the aspects of the design,synthesis of metal oxide sensitive materials and the construction of sensors,a glucose electrochemical biosensor,a H₂O₂ electrochemical biosensor and a triethylamine gas biosensor were constructed,and the catalytic mechanism of each sensitive material was studied by a series of characterization tests.The research results are of great theoretical significance for the design and development of new high-performance biosensors for food safety detection.The specific work is as follows:1.Using carbon cloth as the substrate of electrochemical electrode,the nanowires array of Cu Co₂O₄（Cu Co₂O₄NWs/CC）was directly grown on the carbon cloth by hydrothermal and annealing methods.The structure,morphology and composition of the composite were characterized by Scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and X-ray diffraction（XRD）,a glucose electrochemical sensor was constructed,and the electrochemical properties of the sensor were tested by cyclic voltammetry,electrochemical impedance spectroscopy and amperometric-time curve method.The results showed that Cu Co₂O₄ NWs/CC had good catalytic activity for glucose with two linear ranges.The sensitivity was as high as 7164μA m M^-1cm^-2 when the concentration of glucose was 10μm～1 m M,and 4402μA m M^-1cm^-2 when the concentration of glucose was 1 m M～5 m M,the detection limit was 0.274μM（S/N=3）,and the selectivity and stability are good.The method can be used for the determination of glucose in wine and beverage.2.Using copper foam as the base of electrochemical electrode,the H₂O₂electrochemical sensor was prepared by hydrothermal synthesis of CF@Zn O nanorods（CF@Zn O NRs）and characterized by XRD,SEM and XPS.The results of electrochemical performance test showed that the sensitivity was up to98.7μA m M^-1 cm^-2,when the concentration of H₂O₂ was 5μm～2 m M.The sensitivity was as high as 88.34μA m M^-1 cm^-2,when the concentration of H₂O₂was 2 m M～5.5 m M,and the detection limit was as low as 0.11μM（S/N=3）.It has good anti-interference and reproducibility,and has a good performance in the detection of real milk samples,which is expected to be used in the relevant quality and safety detection of milk products.3.A novel oxygen-rich vacancy material,h-MoO₃/CuO hollow nanoboxes（h-MoO₃/CuO HNBs）,was synthesized by the oxygen vacancy concentration control method control method.It was revealed that the material had a high oxygen vacancy concentration by XRD,SEM and XPS.There are a large specific surface area（444.41 m²/g）and a large number of ultrafine mesoporous heterostructures with an average pore diameter of 3.8 nm.The gas sensing results show that the gas sensor has good sensitivity and high selectivity at the optimum operating temperature of 250℃.The response to 50 ppm triethylamine gas is 18 times higher than that of the pure CuO nanoboxes（CuO NBs）and the selectivity is 6～23 times higher,detection limit is as low as 0.1 ppm.This study provides a new idea for the introduction of oxygen vacancy defects into the design of new sensing materials,and further lays a technical foundation for the development of biosensors for the detection of triethylamine gas produced by fish spoilage.