Application Of Electrochemical Sensors Based On Noble Metals And Carbon Nanotubes In Biological And Food Detection

Some substances such as guanine,adenine,caffeic acid,sunset yellow have effect on human health.Searching for a sensitive,accurate and rapid method determination of these substances has great significance to people's life and health in the fields of clinical diagnosis and food monitoring.The electrochemical sensor has the advantages of the simple equipment,quick response,high sensitive and selectivity,which can provide a better choice for quantitative analysis.As noble metals materials have excellent catalytic activity.Their catalytic activity enhanced significantly with the big surface area when prepared into nano-scale.Carbon nanotubes possess unique structures,excellent electrical properties,catalytic properties and high chemical stability.Combining noble metals and carbon nanotubes is conducive to enrich reactive sites and improve electrochemical performance of materials.In this paper,noble metals and carbon nanotubes were used to fabricate electrochemical sensors for electrochemical determination of guanine,adenine,caffeic acid and sunset yellow,respectively.The contents and results of the study are as follows:?1?A facile strategy was used to fabricate an electrochemical sensor based on one-dimensional?1D?nanocomposites constructed by silver nanowires?AgNWs?and carboxylic multi-walled carbon nanotubes?MWCNTs-COOH?for electrochemical simultaneous determination of guanine and adenine.The AgNWs@MWCNTs-COOH nanocomposites exhibited excellent electrocatalytic activity for the oxidation of guanine and adenine.Under the optimum conditions,the sensor based on AgNWs@MWCNTs-COOH both showed linear range of 0.2-60?mol dm^-33 with detection limit of 0.08?mol dm^-3 for guanine and adenine determination,and approving results were obtained in the real DNA sample detection.?2?A nanocomposites which prepared by octahedral cuprous oxide supported palladium nanoparticles?Cu₂O-PdNPs?via a facile method combined electrochemical deposition with galvanic replacement reaction,and carboxylic multi-walled carbon nanotubes?MWCNTs-COOH?were modified on the surface of glassy carbon electrode?Cu₂O-PdNPs@MWCNTs-COOH/GCE?to fabricate a sensor for electrochemical detection of caffeic acid.Cu₂O-PdNPs@MWCNTs-COOH exhibited remarkable electrocatalytic activity toward the oxidation of caffeic acid.At optimized test conditions,the Cu₂O-PdNPs@MWCNTs-COOH/GCE revealed wider linear ranges of 0.006-60?mol dm^-3with a lower detection limit of 0.002?mol dm^-3 toward caffeic acid,and satisfactory recovery for determination of caffeic acid was obtained in red wine samples.?3?Octahedral cuprous oxide?Cu₂O?was prepared by electrochemical deposition.Cu₂O supported AuNPs composites?Cu₂O-AuNPs?were prepared by spontaneous redox reaction between Cu₂O and HAuCl₄.A nanocomposites sensor was constructed by Cu₂O-AuNPs@MWCNTs-COOH for electrochemical detection of sunset yellow.The experimental conditions were optimized by investigating the effects of different pH,sweeping speed,accumulation time and accumulation potential on the electrochemical behavior of sunset yellow.At optimized test conditions,the Cu₂O-AuNPs@MWCNTs-COOH nanocomposites sensor revealed linear range of 0.02-50?mol dm^-3 with detection limit of0.008?mol dm^-3 toward sunset yellow.In addition,the proposed nanocomposites electrochemical sensor showed good selectivity,stability and reproducibility for sunset yellow determination,and satisfactory results were obtained during the determination of sunset yellow in the real Fanta samples.