Study On Two Electrochemical Detection Methods For NADH

Nicotinamide adenine dinucleotide?NADH?is one of the most important coenzymes in the human body.It plays a role in the transmission of electrons and protons in many redox reactions of the human body.The investigation to the electrochemical oxidation of NADH is important for understanding of the charge transfer in life system.NAD+ is its oxidized form,NAD+/NADH participates in a variety of dehydrogenase reactions and can be used to construct dehydrogenase electrochemical biosensors.However,NADH has a high overpotential on the surface of the bare electrode and is subject to interference from many electroactive substances in the actual sample analysis,resulting in problems such as electrode surface passivation,reduced sensitivity and reproducibility.Through the chemical modification of the electrode surface,it not only can reduce the overpotential of NADH to achieve the electrocatalysis of NADH,but also avoide the impact of interfering substances.In this paper,the enrichment of NADH on the electrode surface was studied based on the effect of boron on the surface of the electrode.The integration of NADH with PMS was carried out to detect NADH at a low potential.The PMS and divalent cations were modified on the surface of the ionic liquid modified electrode The co-electrocatalytic study of NADH is divided into three chapters:1.Chapter 1 mainly on the role of NADH and its body in a brief introduction;and NADH electrochemical sensor progress.2.In the second chapter,a NADH electrochemical sensor with low potential and high sensitivity was constructed by using boric acid functionalized multi-walled carbon nanotubes?MWCNTs?to adsorb phenazine sulfoxylate?PMS?as electrode modifier.Boric acid as the recognition unit can effectively realize the enrichment of NADH on the electrode surface.At the same time,PMS adsorbed on the electrode surface produces electrocatalytic effect on the enriched NADH.The sensor not only has a high sensitivity,but also in the lower potential to achieve detection,effectively avoid the coexistence of coexisting substances.3.In the third chapter,the synergetic effect of redox mediator and divalent cation on NADH was studied.The specific surface area of MWCNTs and ion-liquid?IL?composite electrodes increases the loading of PMS on the electrode surface,and the higher conductivity of IL increases the electron transfer between NADH and the electrode.The electrocatalytic activity of seven kinds of divalent cations on NADH was studied on the above modified electrode.The results showed that Ca²⁺ had the best catalytic effect and 2.3 times of catalytic current,and the electrochemical detection of NADH was realized.