Studies On Construction Of Immunsensor Based On Different Signal Label To Detection Of LAG-3 And ZEA

As a newly discovered tumor marker,lymphocyte activation gene-3（LAG-3）is preferentially expressed in various tumor subtypes and peripheral tissues,and contained value for early diagnosis of tumors.Zearalenone can induce apoptosis and damage DNA through fungal contamination and water transmission,thereby causing toxicity to various systems of the body.A method with high sensitivity and specificity has been developed,and it is essential to detect small molecules of mycotoxins and to detect macromolecular substances of proteins.Electrochemical immunosensor is a new analytical method combining immunology and electrochemical detection technology.It has high sensitivity,rapid reaction time,low cost,easy operation and can be used for on-site rapid inspection.It is important to detect both mycotoxins and macromolecules such as proteins by changing the modified substances.Therefore,by using different immune mechanisms,a novel electrochemical immunosensor was constructed to achieve rapid and accurate detection of tumor markers and mycotoxins.The main research contents and results of the project are as follows:1.A signal-decreased electrochemical immunosensor for the sensitive detection of LAG-3 protein based on a hollow nanobox-MOFs/AuPt alloyIn this work,hollow nanobox metal-organic framework（HNM）nanocomposites were synthesised and utilised for the first time in a signal decreased electrochemical immunosensor for the ultrasensitive quantitative determination of lymphocyte activation gene-3（LAG-3）protein,which is a newly discovered biomarker.With the aid of signal materials,namely,SiO₂-tagged anti-LAG-3 antibody（SiO₂-Ab₂）and the biotin-streptavidin system,the sensor can achieve signal amplification.Encapsulation of tin dioxide-functionalised reduced graphene oxide（rGO-SnO₂）and gold and platinum alloys（AuPt alloys）onto the surface of hollow nanobox metal-organicframeworks（HNMs）wasperformedtoprepare rGO-SnO₂/hollow nanobox-MOFs/AuPt alloys（rGO-SnO₂/HNMs/AuPt）as the matrix.SiO₂-Ab₂,which is used as the signal-decreased label,can be utilised to enhance the distinction of the electrochemical signal after the specific recognition between antibodies and antigens,owing to its large steric hindrance property.In this sensor,this proposed sandwich immunosensor can achieve a high sensitivity,especially in the presence of low concentrations of the LAG-3 protein.Under optimal conditions,this sandwich-designed immunosensor exhibited a sensitive detection of the LAG-3 protein from concentrations of 0.01 ng·mL^-11 to 1μg·mL^-1,with a lower detection limit of 1.1 pg·mL^-1（based on 3σ）.We proposed that this ultrasensitive biosensor can be utilised for the detection of the LAG-3protein in early clinical tumour diagnosis.2.A novel indirect competitively electrochemical immunosensor for ultrasensitive detection of zearalenone using multi-walled carbon nanotubes/chitosan in cereal and feedstuff samplesThe authors describe an electrochemical immunosensor to ultrasensitive detection of zearalenone（ZEA）using carboxylic group-functionalized multi-walled carbon nanotubes/chitosan（cMWCNTs/CS）without blocking step in cereal and feedstuff samples.In electrochemical immunosensor,the substrate catalyzes alkaline phosphatase to produce a stable and strong anodic electrochemical immunosensor at 0.35V in diethanolamine solution.After the glassy carbon electrode（GCE）were modified by the cMWCNTs/CS,electrochemical current response improved distinctly.Its morphology,filed emission scanning electron microscopic,atomic force microscope,differential pulse voltammetry,cyclic voltammetry and electrochemical impedance spectroscopy were researched.Compared with conventional methods,the established immunosensor was exhibited a simpler process and a higher level of sensitive.Under optimal conditions,this method could quantitatively detect ZEA range from 0.01 to 1000ng·mL^-11 with a detection limit of 4.7 pg·mL^-1.The assay could be applied for quantitative monitoring several cereal and feedstuff samples.The results showed satisfactory recovery and consistency with those of High Performance Liquid Chromatography（HPLC）method.