Construction And Analytical Application Of Electrochemical Sensing System Based On Three Nanomaterials Modified Electrodes

The rapid detection of low concentration about chemical substances and biomolecules has received extensive attention in environmental monitoring,chemical analysis,medical care,disease diagnosis and so on.With the attention of society to environmental pollution and public health,the demand for new detection technology is increasing,especially high sensitivity and rapid detection technology.Electrochemical biosensor system can effectively achieve the purpose of rapid and sensitive detection of related substances.The discovery of new nano materials,such as Graphene?Graphene,GR?,Carbon nanotubes?Carbon nanotubes,CNT?and Black Phosphorene?Black phosphorene,BP?,promoted the development of the third generation electrochemical biosensors rapidly.In this paper,three kinds of nanomaterials were used as interfacial modifiers to study the electrochemical behavior of two proteins at the electrode interface.The main contents are as follows.1.As a kind of direct band gap semiconductor with two-dimensional layered structure,BP has shown great application potential in the field of catalysis.The mixture of PEDOT:PSS andBP washomogenized.Furthermore,the third generation enzymesensor?BP-PEDOT:PSS-Hb/CILE?based on hemoglobin?Hb?was constructed using the composite material?BP-PEDOT:PSS?as the carrier,which effectively realized the direct electrochemical behavior of Hb.The electrocatalytic properties of BP-PEDOT:PSS-Hb/CILE for substrates such as trichloroacetic acid?TCA?,sodium nitrite?NaNO₂?and hydrogen peroxide?H₂O₂?were studied.2.An electrochemical biosensor system?BP-PEDOT:PSS-hemin/CILE?was prepared by coating the homogeneous dispersion of BP-PEDOT:PSS and hemin on the CILE.The properties of hemin on the surface of the modified electrode were characterized by cyclic voltammetry.It is proved that hemin can maintain the original structure and biological activity after mixing with BP-PEDOT:PSS composites.The quasi-reversible redox peak,which was the characteristic redox peak of hemin Fe?III?/Fe?II?pair,showed that the BP nanosheets promoted the electron transfer between hemin and CILE.The layered structure of BP provided a large specific surface area and increased the amount of hemin loading at the electrode interface.Under the optimum experimental conditions,the electrocatalytic properties of the electrochemical sensor for TCA,NaNO₂ and H₂O₂ were investigated.The results showed that the detection limit were 0.67 mmol/L?3??,0.33 mmol/L?3??and 1.33mmol/L?3??;the values of K_Mappapp were 4.31 mmol/L,23.31 mmol/L and 11.85 mmol/L?3.Zincoxide-carbonnanofibercomposites?ZnO-CNF?werepreparedby electrospinning and high temperature carbonization,and the electrochemical sensing platform?Nafion/Hb/ZnO-CNF/CILE?was constructed on the surface of the substrate electrode.A protein electrochemical sensor?Nafion/Hb/ZnO-CNF/CILE?was obtained by applying Hb and Nafion onto the electrode surface.The effect of pH value about supporting electrolyte solution,phosphate buffer solution?PBS?,was investigated.Scanning electron microscope?SEM?and transmission electron microscope?TEM?were used for characterizing ZnO-CNF.The results showed that the nanofibers cross each other to form a three-dimensional reticular structure with many holes.Nano-ZnO doped in CNF and formed many granular processes on the surface,this structure is beneficial to increase the specific surface area of the interface.Ultraviolet visible absorption spectroscopy?UV-Vis?and Fourier transform infrared spectroscopy?FT-IR?were used to detect the integrity of Hb structure on the surface of the modified electrode.The results showed that Hb still retain its original structure and biological activity after mixing ZnO-CNF composites.The electrochemical properties and electrocatalytic reduction of related substances were further investigated,such as TCA and NaNO₂.4.Graphene tube?GT?,as an electrode interface modifier,was immobilized on the CILE to construct a novel electrochemical biosensor interface?Nafion/Mb/GT/CILE?.The electrocatalytic behavior of Nafion/Mb/GT/CILE was investigated in pH 2.0 PBS by cyclic voltammetry?CV?and differential pulse voltammetry?DPV?.The results showed that there was a good linear relationship between the peak current and substrate concentration with the wider linear range,the lower detection limit and the higher sensitivity.Therefore,the excellent conductivity of GT can be used in the construction of the third generation enzyme sensor.