Application Of Metal Porphyrin Polymers And Their Composites In Electrochemical Sensors

Electrochemical sensors are analysis and detection devices with simple preprocessing,fast response,easy operation and low cost.It plays an irreplaceable role in sensitive detection of specific objects.When detecting specific targets,appropriate electrode modification materials can improve the sensitivity,specificity,stability and other aspects of the sensor.Therefore,developing new functional electrode modification materials for the construction of electrochemical sensors is an important topic in the field of analysis and detection.In recent years,various materials with excellent performance combined with electrochemical sensors,such as graphene nanomaterials,nitrogen-doped materials,conductive polymers,precious metals and oxides,have improved the analysis and detection capabilities of sensors.According to different target detection objects,selecting different functional types of electrode modification materials and appropriate modification methods can make the constructed sensor have better specificity and sensitivity.Metalloporphyrin polymers have attracted our interest because of their good biocompatibility and biomimetic catalytic activity.The four pyrrole rings of the porphyrin skeleton are linked in the form of conjugated double bonds to form large ring planar molecules,which is more conducive to electron migration and effectively improves the electron transport rate.And the metal ions in the center can coordinate to catalyze the whole sensing process.Metal nanoparticles have smaller particle size,higher specific surface area,more active sites and high conductivity.When it is introduced into the sensor based on metal porphyrin polymer as matrix,it can not only enhance the conductivity of polymer,improve the electron transmission rate,but also produce synergistic effect and realize ultra-sensitive detection.Silver nanoparticles(Ag NPs)have become the most potential metal nanoparticles due to their low biotoxicity,high catalytic activity and easy preparation.Therefore,based on metal porphyrin polymer and silver nanoparticles,a novel electrochemical sensor which can detect small biological molecules sensitively is constructed in this paper.1.A metal porphyrin composite,5,10,15,20-tetrad(4-carboxyphenyl)porphyrin copper(Cu-TCPP),was synthesized by introducing copper ions as the center,and poly(Cu-TCPP)film was polymerized on the electrode surface by cyclic voltammetry.The film has the following three functions: first,excellent biocompatibility of the central metal copper bivalent enables it to accurately identify target molecules.Second,the oxidation process of DNA bases is controlled by the variable valence state of the metal in the center.Third,the formation of large conjugated structures extends electron pathways and accelerates the stripping of electrons from DNA bases,thus achieving the purpose of catalytic oxidation.The sensor can detect four DNA bases individually and simultaneously.It has good reproducibility,stability and anti-interference ability,and can realize accurate and sensitive detection in actual samples.2.It was intended to introduce iron-porphyrin(Fe-THPP)with two-step hydrothermal synthesis and then it prepared poly(Fe-THPP)film on the electrode surface by electropolymerization.Poly(Fe-THPP)has a large specific surface area,high porosity and abundant active sites,which can significantly enhance the electrocatalysis,and the iron ions in the center can specifically recognize phenacetin(PNCT).At the same time,silver nanoparticles(Ag NPs)are introduced on the thin film.Ag NPs are nano-spheres with small radius and have good surface effect.Ag NPs are ideal in vivo catalytic sensing material,which can improve the electrocatalytic performance of the modified electrode for PNCT.The combination of the two electrode materials can not only reduce the resistance and enhance the conductivity,but also form a synergistic catalytic effect to expand the detection range.The sensor has a linear detection range of 0.5-2100 μM,the detection limit was 0.011 μM.In addition,the sensor can sensitively detect PNCT in human serum samples,which has a broad prospect in practical application.