Research And Application Of Chemical Sensor For Insulin And Disease Markers

Insulin is a peptide hormone secreted by pancreatic?cells and has a role in regulating blood sugar levels.The detection of insulin in serum or plasma is of great value in the diagnosis of clinical diabetes-related diseases.The analysis and detection of disease markers can provide a scientific basis for the diagnosis and classification of diseases,and the examination of clinical treatment effects and prognosis.Therefore,chemical sensors for the detection of insulin and disease markers with low development cost,simple detection,high sensitivity and high anti-interference are of great significance.Electrochemical sensor is a combination of electrochemical analysis and sensor technology,while colorimetric sensor is a type of optical sensor.They are all chemical sensors,which have the advantages of fast response,strong anti-interference,simple operation,high sensitivity and low cost,and are widely used in new drug research and development,environmental monitoring,disease treatment and drug analysis.In this paper,a new type of chemical sensor was constructed by electrochemical and UV methods,combining high specific surface area of carbon nanomaterial,excellent catalytic property of metal nanomaterial and high stability of the simulated enzymes,and the sensor was applied to the detection of insulin and disease markers.The main content of this paper can be divided into the following five aspects:1.Ru?bpy?₃Cl₂ was modified onto the DNA-dispersed multi-walled carbon nanotube electrode?MWCNTs-DNA/GCE?by cyclic voltammetry?CV?and characterized by scanning electron microscopy?SEM?.The modified electrode has a good electrocatalytic performance for the insulin with a linear range from 0.02 to 10.0?M,a high sensitivity of 362 nA/?M,and a detection limit of 6.1 nM.Some physiological substance,such as bovine serum albumin,lysozyme,thrombin,glucose and so on,had no obvious interference for detection of insulin.This sensor has been successfully applied to the detection of insulin in human serum.2.Glass carbon electrode?GCE?was modified with?-cyclodextrin-graphene oxide??-CD-GO?by drop coating and electrodeposited with sodium 1,2-naphthoquinone-4-sulfonate?NQS?to obtain NQS/?-CD-GO/GCE.A decrease of the oxidation peak current of NQS,arising from the specific binding of cholyglycine?CG?and NQS through a nucleophilic substitution reaction,was used for indirect detection of CG.The difference of oxidation peak current was linear to the CG concentration in the range of 0.2-60.0?M and the detection limit of CG was 0.061?M.Moreover,the CG sensor showed good repeatability and stability and had been applied to the determination of CG in human serum with satisfactory recoveries.3.A novel electrochemical sensor was constructed based on multi-walled carbon nanotubes and platinum nanoparticle composites?MWCNTs-PtNPs?for simultaneous detection of homovanillic acid?HVA?and vanillylmandelic acid?VMA?.Electrochemical studies showed that MWCNTs-PtNPs modified GCE had an excellent separation performance for HVA and VMA,showing a significant peroxidase mimetic oxidation catalysis.Under optimal conditions,the sensor exhibits good linear responses for HVA and VMA in the range of 0.2-80.0 and 0.5-80.0?M with the detection limits of 80.0 nM for HVA and 173.0 nM for VMA?S/N=3?,respectively.Furthermore,MWCNTs-PtNPs/GCE was successfully applied to the simultaneous determination of HVA and VMA in human urine samples.4.A colorimetric sensor for rapid detection of creatinine was constructed based on the peroxidase activity of FeS₂-carbon black nanocomposites?FeS₂-CB?.FeS₂-CB were prepared by the one-pot method using green reagents such as FeCl₃·6H₂O,L-cysteine and carbon black,and characterized by scanning electron microscope?SEM?,transmission electron microscope?TEM?and X-ray diffraction?XRD?.The difference in absorbance of the reaction system was linear to the creatinine content in the range of 1.0-25.0?M,and the detection limit is0.25?M.The creatinine content in serum samples was determined by the standard addition method.The results showed that the method could be applied to the detection of creatinine in human serum.5.The calcium fluoride?CaF₂?nanoparticles were successfully synthesized by a simple direct precipitation method and used as a peroxidase mimic for rapid and high sensitive colorimetric detection of aldosterone.Experiments had shown that CaF₂ had a peroxidase activity and followed the Michaelis-Menten kinetics.The catalytic mechanism of CaF₂ nanoparticles can be attributed to the catalytic action of CaF₂nanoparticles,resulting in the decomposition of H₂O₂ to produce hydroxyl radicals?·OH?.The effects of solution pH,reaction temperature,the concentrations of TMB and H₂O₂ on the catalytic reaction were investigated.The difference in absorbance of the reaction system had a linear relationship in the concentration range of 2.0-40.0 nM with a detection limit of 0.6 nM.Moreover,the method had been used to detect aldosterone in human serum.