Research On Selective Detection Of Uric Acid Based On Electrochemical Method

Uric acid（UA）is a metabolite of purine in human body.It is an essential substance in human body.The concentration of uric acid in human body is related to various diseases,such as urate nephropathy,gout,and Lesch-Nyan syndrome.However,there are many interfering substances in human body fluids in addition to uric acid,such as ascorbic acid（AA）and reduced nicotinamide adenine dinucleotide（NADH）.Therefore,it is important for the precaution and diagnosis of diversified diseases to detect the concentration of uric acid accurately and selectively.At present,the method of clinical determination of UA is mainly enzymic colorimetric,while the methods of UA detection in laboratory include mainly electrochemical,optical and UA oxidase methods.Electrochemical methods are widely used due to the advantages of small amount of required samples,rapid detection,and high sensitivity.The electrochemical methods of selective detection of UA mainly include the use of enzyme specificity and improving electrode performance to stagger the oxidation peaks of uric acid and interfering substances.However,enzyme has strict requirements about testing environment,such as PH,temperature and it is not suitable for long-term preservation.The method of selectively detecting uric acid by improving the performance of the electrode has the disadvantages of instability,cumbersome modification process,and so on.In order to solve those problems,we combined electro-dynamic jet（E-Jet）technology with MEMS process to fabricate modified carbon electrodes and proposed a scheme for selective detection of UA utilize modified electrode,which modified by electrodeposition method using Nafion as an electrode modifier.A series of investigations were conducted on the selective detection of UA under the interference of AA and NADH.The main contents are as follows:Firstly,carbon electrodes were fabricated using E-Jet technology and MEMS process,and then carbon electrodes were modified with graphene.The performance of the electrode was measured using NADH and potassium ferricyanide（K₃[Fe（CN）₆]）.The detection results of NADH indicated the oxidation peak current on bare carbon electrode was higher than on graphene modified carbon electrode.But oxidation potential of NADH on graphene modified carbon electrode was obviously lower than that on bare carbon electrode.The detection results of K₃[Fe（CN）₆]showed that the potential difference between the oxidation peak and the reduction peak on the graphene-modified carbon electrode was smaller than that of the bare carbon electrode.The detection results of the two electroactive materials showed that the graphene modified carbon electrode has bigger effective electrochemical reaction area and can make the electrochemical reaction easier to occur.At last,UA and AA were also tested with carbon electrodes respectively.Both of them have good results.The linear correlation coefficient between the concentration of UA and the oxidation peak current reached 0.9996,which showed the strong stability of the electrode.Secondly,Nafion-modified electrode（NME）was fabricated by modifying the electrode surface with Nafion and the selective detection of UA was accomplished.In order to further improve the performance of NME,the concentration and modification method of Nafion were optimized and the detection method was optimized.Ultimately,the electrode was modified with1wt%Nafion solution by electrodeposition method.Differential Pulse Voltammetry（DPV）was used to selectively detect UA.The test results showed that the linear correlation coefficient between UA concentration and oxidation peak current was 0.9998,and the sensitivity was9.3655μA/mM.Finally,NME was used to serum detection.And the results indicated that NME can determine UA in serum selectively and the concentration is as low as 0.125 mM,the sensitivity is 0.778μA/mM,and the linear correlation coefficient is 0.9689.