Study On Novel MOFs Electrochemical Sensor And Its Detection Of Biological Small Molecules

It is of great clinical significance for the prevention and treatment of diseases to construct rapid and sensitive analysis methods for the detection of biological small molecules.Compared with traditional detection methods,electrochemical sensors based on chemically modified materials have the advantages of high sensitivity,portable instrument,simple operation process,real-time monitoring and fast analysis,showing excellent analytical ability for quantitative detection of various biological small molecule substances.Metal-organic framework materials（MOFs）are widely used in energy storage and conversion,photocatalysts,drug delivery and sensors due to their large specific surface area,periodically dispersed active sites,harmonized pore structure and uniform particle size.However,the poor stability and poor electrical conductivity of primitive MOFs limit their applications in electrochemical sensors.The methods to overcome these defects include combining the original MOFs with carbon materials with good electrical conductivity and strong chemical stability to form composite materials or using the original MOFs as precursor to synthesize MOFs-derived carbon materials.In contrast,most MOFs-derived carbon materials have hollow structures with cavities and increased active sites,improving the chemical stability and electrical conductivity of the original MOFs.Metal nanoparticles（NPs）are a kind of electrocatalytic materials with excellent chemical stability and electrical conductivity.When NPs are deposited on the surface of MOFs and their derivatives,the sensitivity and accuracy of the detection are further enhanced through the synergistic interaction of the two on the electrochemical sensor.Therefore,two different electrochemical sensors were constructed for the detection of creatinine（Cre）and purine base,so as to provide accurate and sensitive detection methods for the prevention and diagnosis of diseases.The main content of this paper is summarized as follows:（1）An electrochemical sensor for Cre detection was constructed based on Cu-MOF-199@MWCNTsCu-MOF-199@MWCNTs composites were synthesized by doping MWCNTs into Cu-MOF-199,and was modified on the surface of glassy carbon electrode（GCE）by direct drip coating method.Copper nanoparticles（Cu NPs）were further deposited on Cu-MOF-199@MWCNTs/GCE by potentiostatic deposition,and Cu NPs/Cu-MOF-199@MWCNTs/GCE was prepared for electrochemical analysis of Cre.The surface of the modified electrode was characterized by scanning electron microscopy（SEM）,energy dispersive electron microscopy（EDS）,X-ray diffrotometer（XRD）and infrared spectroscopy（FT-IR）,and the electrochemical characterization of the modified electrode was performed by cyclic voltammetry（CV）,electrochemical impedance spectroscopy（EIS）and square wave voltammetry（SWV）.The results showed that the sensor had a large specific surface area and can promote the electron transfer rate.The concentration of the modification solution and the deposition time of Cu NPs were optimized.The underlying Cu-MOF-199@MWCNTs composite increased the load of Cu NPs,which was conducive to the full complexation of Cu²⁺and Cre,and improved the detection sensitivity.Under optimal conditions,Cu NPs/Cu-MOF-199@MWCNTs/GCE was linear in the range of 0.05 to 40.0μM for Cre detection and concentration,with a detection limit（S/N=3）of 11.3 n M.The constructed electrochemical sensor has good stability,reproducibility and selectivity for Cre detection,and can be successfully applied to Cre detection in serum samples.（2）An electrochemical sensor for purine base detection was constructed based on ZIF-8 derived carbon materialA novel electrochemical sensor was constructed to detect guanine（G）and adenine（A）simultaneously by combining gold nanoparticles（Au NPs）with MOFs derivative MC-PNCDs.The electrode construction method is as follows:Firstly,bare GCE was electrochemically activated,and then MC-PNCDs was used as the substrate support material to modify the surface of activated glassy carbon electrode（AGCE）.Finally,Au NPs was deposited on MC-PNCDs/AGCE surface by potentiostatic deposition method to obtain Au NPs/MC-PNCDs/AGCE.Morphology and electrochemical characterization showed that the larger specific surface area of MC-PNCDs combined with the excellent electrocatalytic activity of Au NPs to synergistically improve the electrocatalytic activity of the electrode.The number of activated sections,the concentration of modified solution,the deposition time and the p H value of buffer solution were further optimized.Under the optimal conditions,the linear detection range of G and A was 0.5～160.0μM,and the detection limits（S/N=3）were 72.1 n M and69.6 n M,respectively.The results showed that Au NPs/MC-PNCDs/AGCE sensor has high sensitivity and good selectivity,and has been successfully applied to the electrochemical analysis of G and A in herring sperm DNA and human serum samples.