Study On Electrochemical Sensors For Peroxynitrite

Reactive nitrogen species(RNS)mainly refer to nitric oxide and a series of highly reactiv radicals or nitro compounds coming from the interactions between nitric oxide and reactive oxygen species(ROS),including nitric oxide(NO·),peroxynitrite(ONOO~–),nitrogen dioxide(NO2·),etc.When the concentration of RNS in vivo exceeds the normal physiological level,it will cause oxidative damage to the organism,and lead to various diseases.Among the RNS,ONOO~– has the highest oxidizing and nitrating properties,and the oxidative damage caused by it is also the most serious.Therefore,the detection of ONOO~– in vivo is significant in the diagnosis and treatment of the disease.Electrochemical sensor has the advantages of simple preparation,fast response,high sensitivity,good stability,and it can be continuously monitored online.It is widely used in food testing,environmental monitoring,biological analysis fields.In this paper,the preparation of ONOO~– solution(PON)is studied,and two kinds of electrochemical sensors based on the nano materials were constructed for ONOO~–.The contents are as follows:1)Two methods of preparation of PON,the reaction between hydrogen peroxide and nitrite: under acidic conditions,peroxynitrous acid(ONOOH)is formed from the reaction of excessive hydrogen peroxide with nitrite,then NaOH is added to quench the reaction to form ONOO~–;The replacement in a Two-Phase system: under alkaline conditions,hydrogen peroxide will exist in the form of peroxide ions,isoamyl nitrite will react with peroxide ions to generate ONOOH and isoamyl acetate,and isoamyl acetate will react with ONOOH to form ONOO~– finally.2)MWCNTs was dropped on the bare glassy carbon electrode(GCE),and then the modified electrode was coated with ebselen solution,thus an electrochemical sensor for peroxynitrite detection was successfully constructured.The results show that under the optimal conditions,current response of the fabricated sensor Ebselen/MWCNTs/GCE to PON shows a good linear relationship with the concentration of PON in the range of 135 ?mol/L ~ 945 ?mol/L,and the calculated detection limit was 97.29 ?mol/L(S/N=3).3)Melamine was polymerized on the surface of GCE modified with MWCNTs by Cyclic voltammetry(CV)method,and then gold nanoparticles were electrodeposited on the modified electrode,the modified electrode was immersed in the hemin solution,thus an electrochemical sensor for peroxynitrite detection was successfully constructured.The results show that under the optimal conditions,current response of the fabricated sensor Hemin/AuNPs/PMel/MWCNTs/GCE to PON shows a good linear relationship with the concentration of PON in the range of 10 ?mol/L ~ 350 ?mol/L and 350 ?mol/L ~ 1100 ?mol/L,and the calculated detection limit were 0.12 ?mol/L and 47.61 ?mol/L,respectively(S/N=3).