Fabrication Of Novel Electrochemical Biosensors Based On Layered Nanomaterials

Biosensor possesses important value in physic,environmental monitoring,food and military,and it has caused great concern to all countries in the world.Layered nanomaterials have many specialities, such as orderly structure,adjustable chemical composition, intercalationable,assembliable,and nanosheets obtained from the delamination of layered nanomaterials have a more open structure.Novel electrochemical biosensors have been fabricated based on zirconium phosphate,layered manganese oxide,and nanosheets gained from these layered nanomaterials in this topic.These biosensors possess good stability,anti-interference,and other favorable properties.It provides a new idea to develop new type of electrochemical biosensors,and it has broad application prospects.1.Horseradish peroxidase(HRP)has been immobilized in zirconium phosphate nanosheets(ZrPNS)which are derived via the delamination of layeredα-zirconium phosphate(α-ZrP).X-ray powder diffraction(XRD) and field emission scanning electron microscopy(FESEM)results revealed that HRP-ZrPNS film remained unorderly structure for the effect of HRP.Fourier transform infrared(FTIR)spectra results revealed that HRP almost remained the basal structure in ZrPNS film.Direct electrochemistry of HRP in ZrPNS film was investigated.Based on these, a third generation reagentless biosensor was constructed for the determination of hydrogen peroxide(H₂O₂).Rapid response and wide linear range to H₂O₂ has been obtained with this biosensor.2.Alternate adsorption of oppositely charged myoglobin(Mb)and ZrPNS were used to assemble {Mb/ZrPNS}_n layer-by-layer films on solid surfaces by electrostatic interaction between them.Electrochemical impedance spectroscopy(EIS)was used to monitor or confirm the growth of the films.FESEM results indicate that edges of ZrPNS overlap with each other and are faintly recognized,and a smooth film without cracks was formed on the surface of the substrate.The direct electrochemistry of Mb was realized in {Mb/ZrPNS},,films at glassy carbon electrodes(GCE), showing a pair of well-defined,nearly reversible cyclic voltammetry(CV) peaks for the Mb heme Fe^â…¢/Fe^â…¡redox couple.Compared with other Mb layer-by-layer films with nonconductive nanoparticles or polyions, {Mb/ZrPNS}_n films showed much improved properties,such as higher surface concentration of electroactive Mb(Γ*),and better electrocatalytic activity toward reduction of H₂O₂. 3.A cationic biocompatible polymer-polyquaternium(QY)has been used to immobilize glucose oxidase(GOD).FTIR spectrophotometer, circular dichroism(CD)and Ultraviolet-visble(UV-Vis)results indicate that GOD retains its basal structure within the polymer film.The form of the QY film and synthesized composite film have been characterized using FESEM.The first-generation glucose biosensor based on QY exhibits rapid response and good sensitivity.In addition,the characteristics of the second-generation biosensor with ferrocene(Fc)as an electron mediator have also been discussed.The Fc mediated biosensor exhibits a good anti-interference ability,and the extended linear range.Furthermore,QY is inexpensive,and the enzyme immobilization method is very simple, which make the biosensor be promising for practical application.4.A novel biocompatible polyquaternium(QY)-manganese oxide nanosheet(MNS)nanocomposite has been prepared and shown to be a promising matrix for horseradish peroxidase(HRP)immobilization.The resulting HRP-QY-MNS film was characterized by Fourier transform infrared(FTIR)and circular dichroism(CD)spectroscopy,which indicated that HRP retained its native structure in the nanocomposite film. An HRP-QY-MNS film-modified glassy carbon electrode exhibited a pair of well-defined and quasi-reversible cyclic voltammetric peaks centered at -0.272 V(vs.Ag/AgCl)in pH 7.0 phosphate buffer solution.The direct electrochemical behavior of HRP was greatly enhanced in the QY-MNS nanocomposite film compared with that in single-component QY or MNS films.The immobilized HRP showed excellent electrocatalysis in the reduction of hydrogen peroxide(H₂O₂),which was exploited in the construction of an H₂O₂ biosensor.The biosensor exhibited rapid response and good long-term stability.5.Methylene blue(MB)has been intercalated into layered manganese oxide(birnessite,shortening as Bir)by a delamination/reassembly process and the resulting MB-intercalated bimessite(MB-Bir)material characterized by XRD,FTIR spectroscopy,and electrochemical measurements.A novel reagentless hydrogen peroxide biosensor was fabricated by using the MB-Bir as an electron mediator.Cyclic voltammetry and amperometric measurements demonstrated that MB coimmobilized with HRP displayed good stability and that electrons were efficiently shuttled between HRP and the electrode.The biosensor showed good properties.Moreover,the biosensor exhibited a good stability and anti-interference ability.