The Fabrication Of Nanoparticles-Based Electrochemical Biosensors And Their Applications In Chinese Herbal Medicinal Ingredients Analysis

Carbon fiber microelectrode(CFME)is a micro electrochemical sensor with the characteristics of small size,simple preparation and high sensitivity.It is often used to detect neurotransmitters,heavy metals and drug components.Nano gold(AuNPs),nano platinum(Pt Nps)and nano ruthenium(Ru Nps)are precious metal materials with excellent physical and chemical properties,such as large specific surface area,strong conductivity and good biocompatibility.In this paper,precious metal nano materials are used as the main modification materials of CFME,which improves the electrocatalytic activity,stability and selectivity of CFME,expands the application of CFME in the analysis of traditional Chinese medicine,and further explores the interaction between drug components and DNA.The specific research contents are as follows:(1)In this study,PtNPs were prepared by trisodium citrate reduction method.Nano platinum was modified to the surface of CFME by electrochemical deposition.The electrocatalytic activity of the modified electrode for luteolin was investigated by differential pulse voltammetry(DPV),cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).The stability,selectivity,accuracy and sensitivity of PtNPs/CFME were investigated,and the quantitative determination of luteolin in biological samples was realized.(2)In this paper,gold nanoparticles-graphene quantum dots were prepared by in-situ growth method.Nano silver and gold nanoparticles-graphene quantum dots composites were modified on carbon fiber microelectrode by electrochemical deposition method to obtain the gold nanoparticles-graphene quantum dots/nano silver/carbon fiber microelectrode(Au-GQDs/AgNPs/CFME).The morphology of the modified materials was characterized by scanning electron microscope and transmission electron microscope.The results showed that the modified materials had good dispersion and uniform particle size.The electrochemical behavior of quercetin(Qu)at different modified electrodes was investigated by cyclic voltammetry(CV)and differential pulse voltammetry(DPV).The electrodeposition time,scanning speed and p H of buffer solution were optimized.The oxidation mechanism of quercetin on Au-GQDs/AgNPs/CFME was explored,and the sensor can be used for the determination of quercetin in real samples.(3)In this study,a highly sensitive electrochemical sensor modified with AuNPs-RuNPs was constructed for the quantitative detection of catechin.HRTEM,SEM and elemental energy spectrum were used to investigate the morphological characteristics and elemental composition of the modified materials.The optimal scanning rate and pH of buffer solution were selected.The electrochemical response,stability,anti-interference and sensitivity of AuNPs/RuNPs/CFME were investigated,and the quantitative detection of catechin in mouse serum was realized.(4)Electrode sensitivity and selectivity in complex biological matrices are major challenges in the development of electrochemical sensors.Bimetallic nanoparticles provide a new perspective for enhancing electrocatalytic property because of some specific synergetic effects.In this work,platinum nanoparticles(PtNPs)and gold nanoparticles(AuNPs)modified carbon fiber microelectrode(PtNPs/AuNPs/CFME)was fabricated to determine aesculin and aesculetin simultaneously.Differential pulse voltammetry(DPV)method was conducted for the electrochemical sensing of aesculin and aesculetin,the modified electrode displayed high electrocatalytic activity for the redox of these two drugs.Furthermore,an electrochemical investigation of the interactions of these two drugs with Calf thymus double stranded DNA(dsDNA)was investigated by PtNPs/AuNPs/CFME,the decrease in peak currents is proportional to DNA concentration and can be used to detect DNA.The electrode was successfully used to measure aesculin and aesculetin in mouse serum and urine with 98.0–104.8 %recovery.The novel electrochemical probe possessed excellent performances of high sensitivity,good reproducibility,and simplicity of fabrication,which will facilitate effective detection of aesculin and aesculetin for metabolic kinetics study.