Preparation Of The Electrochemical Sensor For Hemoglobin Based On Magnetic Molecularly Imprinted Nanoparticles

Molecularly imprinted polymers?MIPs?with many imptinted cavities that are complementary in spatial structure and functional groups to the target molecules could specifically recognize the target molecules.It is widely applied in many fields,such as solid phase extraction,mimic enzyme catalysis and biosensors owe to its stability on chemical and mechanical property,high selectivity and good repeatability.Hemoglobin?Hb?is an iron-containing metalloprotein which plays an important role in vital movement.Therefore,the accurate measurement of its concentration is of practical significance.Because of the low cost,easy operation and high sensitivity,electrochemical detection of Hb has been the focus,and it also provides the basis study for the third generation enzyme biosensor.In this thesis,hemoglobin magnetic surface-imprinted nanoparticles?MMIPs NPs?based on Fe₃O₄@SiO₂ NPs for hemoglobin were synthesized.A fast and selective electrochemical sensor for determination of Hb and an electrochemical biosensor based on immobilization of Hb on MMIPs NPs for detection of nitrite?NO₂^-?had been developped.The main contents of the thesis were listed as follows:1.Hb MMIPs NPs were synthesized by using Hb as the template,tetraethoxysilane as the monomer,Fe₃O₄@SiO₂ as the carrier.TEM photographs showed that MMIPs NPs with uniform core-shell strucyure had regular structures and good monodispersity,and the average diameter was 80 nm?RSD = 6.2%,n = 100?.The thickness of shell was about 12 nm.Thermodynamic and kinetic adsorption experiments showed that the saturation adsorption capacity of MMIPs NPs for Hb was 107 mg/g,and the adsorption equilibrium was achieved with in 1 h.The separation fators for Hb to bovine serum albumin?BSA?,horseradish peroxidase?HRP?,lysozyme?Lyz?was ?Hb/BSA = 7.13,?Hb/HRP = 3.69,?Hb/Lyz = 2.76,respectively.It revealed that MMIPs NPs could specifically recognize Hb.2.A fast and selective electrochemical sensor for determination of Hb was developed based on MMIPs NPs modified on the magnetic glassy carbon electrode?MGCE?.Hb could be determined by directly electrochemical oxidization of Hb on the modified electrode.An external magnetic field using a magnetic electrode increased electrochemical response to Hb by two times.Imprinting Hb on the surface of Fe₃O₄@SiO₂ shell shortened the response time within 7 min.Under optimum conditions,differential pulse voltammetry?DPV?showed that the response of Hb on the imprinted sensor was 2.8 times as much as that on the non-imprinted sensor.Moreover,the separation factors of Hb to horseradish peroxidase was 2.6.The oxidation peak had a linear relationship with Hb concentration in the range of 0.005-0.1 mg/m L?r = 0.998?with a detection limit?S/N = 3?of 0.0010 mg/m L.The sensors were successfully applied to analysis of Hb in whole blood samples with recoveries between 95.7% and 105%.3.A biosensors for determination of NO₂^-was developed based on immobilization of Hb on MMIPs NPs modified on MGCE.Under optimum conditions,differential pulse voltammetry?DPV?showed that an external magnetic field using a magnetic electrode increased the sensitivity of the sensor.The response of NO₂^-on the Hb/MMIPs NPs MGCE increased by 18% compared to that on the Hb/MMIPs NPs GCE.Due to many rebinding sites of MMIPs NPs,the sensor could adsorb more Hb.So,the response of NO₂^-on the Hb/MMIPs NPs MGCE was larger than that on the Hb/MNIPs NPs MGCE.The reduction peak current had a linear relationship with NO₂^-concentration ranged from 10 ?mol/L to 100 ?mol/L with a detection limit?S/N = 3?of 5 ?mol/L.The common inorganicons,such as Na⁺,K⁺,Mg²⁺,Ca²⁺,F^-,Cl^-,SO₃^2-,NO₃^-,PO₄^3-,SO₄^2-,did not interfere with the determination of NO₃^-.The biosensor had good repeatability and long operation life.This biosensor could be used in the determination of NO₂^- in actural samples.