Six Inositol Phosphate (calcium, Magnesium And Zinc) Membrane Preparation And Its Application In The Sensor

Biosensors are analytical devices composed of a recognitionelement of biological origin and a physicochemical transducer．Thebiological element is capable of sensing the presence，activity orconcentration of a chemical analyte in solution． The sensing takesplace either as a binding event or a biocatalytical event． Theseinteractions produce a measurable change in a solution property，which the transducer converts into a quantifiable electrical signal．Theprinciples， types and applications of biosensors in environmentalinspection，food production，clinical medicine an military defence werereviewed，and the trends in research were predicted．Protein-based voltammetric biosensors have received more andmore research interest，and various kinds of nanomaterials have beenemployed．The nanomaterials are used not only as the hosts for proteinimmobilization，but also as a friendly platform for the assembly of proteinmolecules to enhance the electron transfer process between proteinmolecules and electrodes．Phytic acid is an environment-friendly naturally occurring acidwhich has6noncoplanar phosphate bonds structurally．Its intrinsicproperty makes PA show a strong tendency to complex and chelatewith metal or metal oxide nanoparticles． These new functionalmaterials act as good electron transfer mediator were widely used inthe field of electrochemistry， which attracted great interest ofresearchers to explore their configuration， property andapplicationsel．This thesis is aimed at solving the problem by means ofnanotechnology，self-assembly and other technique，employing thefunctional nanomaterials to construct series electrochemical sensinginterface．The specific preparation of the three kinds of sensors have been developed as follows：（1） A novel composite electrode of Nafion/HRP/Ca-IP6/GCE hasbeen constructed for the electrochemical detection ofH2O2． Nafion/HRP/Ca-IP6/GCE was characterized with UV–visabsorption spectroscopy，cyclic voltammetry（CV）and electrochemicalimpedance spectroscopy（EIS）．Experimental results showed that theabsorbed HRP retained its bioactivity and realized direct electrontransfer due to the improved biocompatibility of calciumphytate． Moreover， the biosensor displayed excellentbioelectrocatalytic ability toward the reduction of H2O2with a linearresponse to H2O2over a concentration range from2.67×10^-7 to1.07×10^-6 mol/L， and a constantwas estimated to be0.259mmol/L． Thebiosensor exhibited low detection limit，high enzymatic activity andgood reproducibility and stability．（2） This chapter is going to construct a simple biosensor byimmobilizing horseradish peroxidase（HRP）onto magnesium phytatenanoparticles．Due to the strong chelating ability between phosphatesand metal ions，we synthesized a new mesoporous material-magnesiumphytate．And then a high sensitive horseradish peroxidase（HRP）biosensor was prepared based on the proposed mesoporousinterface． Cyclic voltammetry were applied to characterizing theprocess of forming nanofilm．Hydrogen peroxide was detected with theaid of hydroquinone mediator to transfer electrons between theelectrode and HRP．The immobilized HRP displayed the feature of aperoxidase and gave an excellent electrocatalytic response to thereduction of H₂O₂．The biosensor showed a linear response to H2O2over a concentration range from1.00×10^-7 to9.80×10^-5 mol L^-1 with adetection limit of9.80×10-8mol L^-1（S/N=3）．Thewas estimated to be0.121mmol L^-1． The constructed sensor shows good stability and reproducibility，and is a sensitive hydrogen peroxide biosensor withoutthe redox medium．（3） Due to the strong chelating ability between phosphates andmetal ions， we synthesized a new anthoid nanomaterials-zincphytate．Then we tried to employ the anthoid film of zinc phytate as asubstrate for making the HRP based biosensor by drop-coating methodand investigate the electrochemical behavior of enzyme．The UV-visabsorption spectroscopy and electrochemical results showed that thiskind of material has a great biological affinity and it can preventdamage to biological activity of enzyme during immobilization．Theabsorbed HRP realized direct electron transfer and displayed goodbioelectrocatalytic ability toward the reduction of H2O2with a linearresponse to H2O2over a concentration range from1.33×10^-7 to1.08×10^-5 mol L^-1， and a detection limit of1.00×10^-7 mol L^-1 at asignal-to-noise ratio（S/N）=3． The Michaelis-Menten constantwasestimated to be0.0850mmol L^-1．Moreover，the biosensor is a simpleand effective strategy for fabrication of hydrogen peroxide （H2O2）biosensor，possesses long-time stability and reproducibility．...