Research On Nitric Oxide Electrochemical Sensing Based On Metal-Organic Polymers Film Interface

As a small free radical molecule,nitric oxide（NO）is an important cell signaling substance in living systems,and plays a critical role in physiological functions,such as vasodilation,apoptosis and innate immune response.Essential amount of NO can enhance cell proliferation and accelerate wound healing in a growth factor-free medium,but excessive amount of NO may cause tumor disease or induce inflammation.It’s of great significance to develop new method to detect NO released from biological tissues and NO donor drugs.Among the reported methods,NO electrochemical sensors have attracted much attention due to the advantages of compact equipment,simple operation,fast response,and high sensitivity.Exploring new sensing membrane interface with high sensitivity and selectivity has been challenging.Metal-organic polymers（MOPs）have attracted extensive attention in the fields of catalysis and separation due to their characteristics of unsaturated metal coordination sites and structural diversity,which have also been applied into electrochemical sensors in recent years.However,the research on NO electrochemical sensing and electrocatalytic mechanism based on MOPs is seldom reported.In this paper,two new types of NO electrochemical sensors were developed based on MOPs nanomaterials electrochemical sensing interface,and the NO releasing of NO donor drugs and mouse liver cells were determined.The main contents include the following two parts:（1）An iron-based complex Fe（II）-BTC nanofilms was electrodepostied on the surface of glassy carbon electrodes to prepare a novel mimetic enzyme sensor for NO.The morphology and composition of Fe（II）-BTC complex films were characterized by scanning electron microscopy,energy dispersive spectrometer and Fourier transform infrared.The response of the mimetic enzyme sensor was investigated by diverse electrochemical methods,including voltammetry,electrochemical impedance spectroscopy,chronocoulometry and chronoamperometry,and the electrocatalytic oxidation mechanism of NO was proposed.The sensor exhibited good catalytic activity for electrochemical oxidation of NO and followed Michaelis–Menten behaviors.The mimetic enzyme sensor not only had the features of easy preparation,low cost and high stability,but also had a wide linear detection range(18 nmol L^-1-9μmol L^-1)and a low detection limit(7.2 nmol L^-1),which had been used to detect the NO photorelease from SNP successfully.（2）Amino-functionalized Cu-MOFs were synthesized by hydrothermal method,and a Cu-MOF/Nafion modified glass carbon electrode was prepared,then Au NPs were electrodeposited to develope a NO electrochemical sensor based on Cu-MOF/Nafion/Au NPs nanocomposite membrane interface.The interface modification materials were characterized by scanning electron microscopy and infrared spectroscopy.The results showed that Cu-MOF/Nafion/Au NPs composites exhibited a specific tremella flower-like structure.The electrocatalytic oxidation process of NO on the nanocomposites interface was investigated by cyclic voltammetry,chronoamperometry and electrochemical impedance spectroscopy.The current response of the NO electrochemical sensor showed a linear relationship with the NO concentration in the range of 18 nmol L^-1-144μmol L^-1,and the detection limit was 1.8 nmol L^-1.In addition,the sensor had good selectivity for NO and had been used to detect NO releasing in mouse liver tissue.