Study On The Application Of Nano-Microelectrochemical Sensor Arrays In Bioanalysis

In recent years,electrochemical sensors have attracted the interest of many researchers due to their simple operation,low cost,rapid detection,in-situ detection,high sensitivity,and good flexibility,making them a novel analytical method.Among them,the nano-microelectrochemical sensor array has made more efforts in miniaturization and refinement,which makes it show great application potential in biological analysis.Not only can the analyte be qualitatively and quantitatively,it can also be dynamically monitored online,providing a certain reference for plant growth,physiological mechanism research,and medical applications.This thesis uses carbon nanotubes,electrochemically reduced graphene oxide,boron nitride,two-dimensional transition metal carbides,metal nanoparticles,etc.to modify the carbon fiber microelectrode array to construct three new nano-microelectrochemical sensor arrays.For the determination of some biological samples.The main research contents of this paper are as follows:(1)A gold nanoparticle/single-walled carbon nanotube-hexagonal boron nitride composite modified carbon fiber microelectrode array(Au NPs/SWCNT-h BNs/CFMEA)simultaneously determinates melatonin and epinephrine.Functionalize single-walled carbon nanotubes by mixed acid to improve the water solubility,and then combine with hexagonal boron nitride to form composites(SWCNT-h BNs)and then modify them on the prepared carbon fiber microelectrode array by immersion.Then,gold nanoparticles(Au NPs)are deposited on the surface of the electrode by electrodeposition to form an nano-microelectrochemical sensor array(Au NPs/SWCNT-h BNs/CFMEA).After characterizing the electrode and optimizing the preparation conditions,the electrochemical behavior of epinephrine and melatonin on the electrode was studied by cyclic voltammetry.The epinephrine and melatonin can achieve a good separation and response.The experiment found that Au NPs and SWCNT-h BNs have high catalytic activity for the electrochemical oxidation of epinephrine and melatonin.Epinephrine and melatonin were measured separately and simultaneously by differential pulse voltammetry.The linear range of epinephrine measured separately was 0.8-30?M,and the detection limit was 6.77 n M.The linear range of melatonin was 1.5-100?M,and the detection limit was 89.4 n M.At the same time,the linear ranges of epinephrine and melatonin were 0.75-40?M and 0.75-40?M,and the detection limits were33.9 n M and 62.2 n M,respectively.The nano-micro electrochemical sensor array was applied to human serum samples to simultaneously determine epinephrine and melatonin,and the recovery rate was good.(2)Nano-cobalt ferrite/two-dimensional transition metal carbide modified carbon fiber microelectrode array(Co Fe₂O₄/MXene/CFMEA)for sensitive determination of xanthine.The etched and stripped two-dimensional transition metal carbide(MXene)is modified on the prepared carbon fiber electrode array by potentiostatic amperometric method,and then nanometer cobalt ferrite(Co Fe₂O₄)is deposited on the electrode to construct the nano-microelectrochemical sensor array Co Fe₂O₄/MXene/CFMEA.The electrochemical sensor was characterized and conditions optimized,and then the electrochemical behavior of xanthine in it was studied.Through experiments,it is known that MXene and Co Fe₂O₄ can increase the peak oxidation current of xanthine,improve the electrochemical activity of the electrode,and catalyze the reaction.The linear range and detection limit of xanthine were determined by square wave voltammetry,and a wide linear range(0.05 n M-10?M)and a very low detection limit(8.71 p M)were obtained.The nano-microelectrochemical sensor array has good selectivity,reproducibility,repeatability,and stability,and has been successfully applied to sensitively detect xanthine in shrimp samples.(3)Montmorillonite/electrochemically reduced graphene oxide-boron nitride composite modified carbon fiber microelectrode array(MMT/RGO-BNs/CFMEA)simultaneously determines tryptophan and salicylic acid.By compounding graphene oxide and boron nitride,the compound is electrochemically reduced to the prepared carbon fiber electrode array,and then the electrode is modified with montmorillonite by cyclic voltammetry to obtain a new type of nano-microelectrochemical sensor array MMT/RGO-BNs/CFMEA.Cyclic voltammetry is used to study the electrochemical behavior of tryptophan and salicylic acid on the modified electrode.Both them can achieve excellent peak separation and nice electrochemical response.The electrochemical determination of tryptophan and salicylic acid was carried out by differential pulse voltammetry.The linear range of the oxidation peak current and concentration of tryptophan determined separately was 0.01-10?M,the detection limit was 0.88 n M,and the linearity of salicylic acid was The range is0.45-30?M,and the detection limit is 90.84 n M.The linear ranges of tryptophan and salicylic acid obtained by simultaneous determination were 6 n M-3.9?M and 0.4-10.5?M,and the detection limits were 0.93 n M and 101.51 n M,respectively.The electrode has good stability and selectivity,and has been successfully used in the study of the influence of salt stress on the content of tryptophan and salicylic acid in plants.