Research On The Hydrogen Peroxide Biosensor Based On Ferromagnetic Materials Modified Electrode

Magnetic nanomaterial is one of the most important nanomaterials, because it not only possess the properties, such as high surface activity, small size effect, photo-electron effect and catalysis, but also for its abundant functional groups on the surface and superparamagnetism property, which is more easy for separation, transfer and collection. It has been applied extensively in many research fields,such as enzyme immobilization and electrocatalytical analysis.The main purpose of this paper is to study the application of the amino-silane magnetic nanoparticles (A-SMNPs) and porous-magnetic chitosan microspheres (p-MCMS) in the electrocatalytical analysis of hydrogen peroxide (H₂O₂), the immobilization of redox enzymes, including hemoglobin and horseradish peroxidase and their biosensing. The main content of this paper is listed as follows:1. Amino-silane functionalized Fe3O4 magnetic nanoparticles (A-SMNPs) were prepared and were mixed with graphite powder to construct A-SMNPs modified carbon paste electrodes (A-SMNPs/CPEs). The electrochemical behaviour of hydrogen peroxide was studied on the modified electrodes. Without addition of any enzyme, the A-SMNPs modified electrodes exhibited excellent electrocatalytic behaviour towards the reduction of hydrogen peroxide. The linear ranges of the response to H₂O₂ was 8.0×10–5 to 14×10–3 mol·L^–1, with a detection limit of 4.3×10–5 mol·L^–1. Moreover, the sensor retained splendid activity after one month.2. Amino-silane magnetic nanoparticles (A-SMNPs) were mixed with graphite powder to construct A-SMNPs-contained carbon paste electrodes (CPE). Hemoglobin (Hb) was then immobilized on the electrode surface to form Hb/A-SMNPs/CPE biosensors. The biosensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that Hb was stably immobilized on the electrode, and have exhibit excellent electrocatalytic activity to the reduction of hydrogen peroxide without the aid of an electron mediator. When used for amperometric measurement of H₂O₂, the prepared biosensor displayed good sensitivity, selectivity and stability. A linear detection range of H₂O₂ from 1.0μmol·L^–1 to 2.0 mmol·L^–1 and a detection limit of 0.27μmol·L^–1 (S/N=3) was obtained. The apparent Michaelis-Menten constant was calculated to be 0.85 mmol·L^–1, indicating that the immobilized Hb had high enzymatic activity to H₂O₂. 3. A drop of homogeneous Amino-silane magnetic nanoparticles (A-SMNPs) dispersion was cast on the surface of a glassy carbon electrode (GCE) to fabricate a A-SMNPs modified GCE, with the help of PDDA, horseradish peroxidase (HRP) was successively immobilized on the surface of the A-SMNPs/GCE. Under optimal conditions, hydrogen peroxide exhibited excellent response.4. A amperometric biosensor for the detection of hydrogen peroxide was described. The biosensor was constructed by immobilizing horseradish peroxidase (HRP) and porous-magnetic chitosan microspheres (p-MCMS) on the surface of carbon paste electrode. Due to the porous and biocompatible properties of the magnetic chitosan microspheres, The immobilized HRP gives excellent response to hydrogen peroxide in a few seconds with a detection limit of 0.27μmol·L^–1 (based on signal/noise =3). Linear range was 0.49μmol·L^–1 to 0.20 mmol·L^–1. The biosensor exhibited a satisfactory stability.