Preparation And Application Of Electrochemical Enzyme Sensor Based On Hierarchical Porous Nanomaterials

With the technology continuous improving,electrochemical enzyme sensors with high sensitivity and selectivity,rapid response,low cost and other good performances have been a class of analysis tools,which impact many fields,including clinic,pharmaceutical,food,environment and military.Among them,acetylcholinesterase(ACh E)electrochemical sensors are widely used in organophosphate and carbamate pesticide detection.The key step in building an electrochemical enzyme sensor is the modification of the electrode surface.Hierarchical porous bioactive glass materials have been well studied in the field of bone defect repair and drug release,but used as a modifier in electrochemical analysis is not common.In this paper,three kinds of ACh E electrochemical sensors modified by hierarchical porous bioactive glass materials were designed.ACh E was fixed on hierarchical porous bioactive glass materials by physical adsorption method and covalent bonding method.The properties of the three materials were studied by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,specific surface,Fourier transform infrared spectroscopy,thermogravimetric analysis and X-ray photoelectron spectroscopy.After the performances of three kinds of electrochemical enzyme sensors were studied and optimized,the detections of malathion and diazinon as organophosphorus pesticide model were completed.1.Preparation and characterization of hierarchical porous bioactive glass with Herba leonuri pollen as biological templateHierarchical Porous Bioactive Glass(HMBG)microspheres were fabricated by using bio-template method and hydrothermal method.HMBG with multiscale porosity was prepared by using natural Herba leonuri pollen grains and non-ionic block copolymer P123(EO20PO70EO20)as double template.HMBG not only has good biocompatibility and stability,but also the larger specific surface area can promote the adsorption on the surface and the transmission in the channel of biomolecules.Polyamide-amine(PAMAM)dendrimers with amino-terminal groups were grafted on HMBG microspheres to obtain more complex multi-stage nanocarriers(HMBG-PAMAM).2.Preparation and application of electrochemical sensor for immobilization of acetylcholinesterase by physical adsorption methodThe ACh E was respectively immobilized on HMBG and HMBG-PAMAM by physical adsorption method.Two kinds of HMBG-ACh E and HMBG-PAMAM-ACh E electrochemical sensor were prepared by modified carbon paste electrode.The results showed that the concentration of malathion was 0.02 ppb ~ 50 ppb and 50 ppb ~ 600 ppb,and the concentration of pesticide was linear with the current inhibition rate.The detection limit of the HMBG-ACh E electrochemical sensor is 0.0135 ppb(S/N=3)and the detection limit of HMBG-PAMAM-ACh E electrochemical sensor is 0.0192 ppb(S/N=3).3.Preparation and application of electrochemical sensor for immobilized acetylcholinesterase by glutaraldehyde covalent bonding methodThe HMBG-GA-ACh E electrochemical sensor was prepared by covalent bonding method.The amino group of ACh E was covalent bonding with the grafted amino group on HMBG using a bifunctional reagent glutaraldehyde(GA).The results showed that the concentration of malathion and diazinon was 0.02 ppb ~ 10 ppb and 10 ppb ~ 600 ppb,and the concentration of pesticide was linear with the current inhibition rate.The detection limits of the HMBG-GA-ACh E electrochemical sensor for malathion and diazinon were 0.0156 ppb(S/N=3)and 0.0172 ppb(S/N=3)respectively.The results of three kinds of electrochemical enzyme sensors show that the hierarchical porous bioactive glass can be used as a carrier for immobilized acetylcholinesterase,which can keep the activity of the enzyme well.Three kinds of acetylcholinesterase electrochemical sensor with high sensitivity,wide detection range,low detection limit,can achieve the actual samples detection.