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摘要
A sensitive and selective amperometric immunosensor for chloramphenicol (CAP, IUPAC name: 2, 2-Dichloro-N-[2-hydroxy-1-(hydroxymethyl)-2-(4-nitrophenyl) ethyl] acetamide) detection based on magnetic nanocomposites modify screen-printed carbon electrode (SPCE) as a disposable platform was fabricated. Graphene sheets (GS)-Nafion (Nf) dispersed solution was first dropped on the SPCE and then Fe3O4-Au nanoparticles (GoldMag particles, GMP) coated bovine serum albumin-CAP (BSA-CAP) conjugates was absorbed on it with the aid of external magnetic field. X-ray powder diffractometer (XRD), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were employed to characterize the synthesized GS and the construction processes of the modified electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study its electrochemical properties. The content of CAP was determined with a competitive immunoassay mode. When different concentration of CAP and 1.0 mu g/mL anti-CAP were added to the phosphate buffer solution (PBS) containing 2.0 mmol/L K-3[Fe(CN)(6)], the increase ratio of the DPV current (CI%) was proportional to the concentration of CAP over the range from 2.0 ng/mL to 200.0 ng/mL after incubation for 5.0 min at 25 degrees C. The detection limit was 0.82 ng/mL (S/N=3). The immunosensor was employed to determine CAP in milk samples and the results were consistent with high-performance liquid chromatography (HPLC) method. The proposed amperometric immunosensor is sensitive, selective, rapid, magnetic field controllable, low sample consumable and disposable. Results obtained in this study demonstrate that the immunosensor was suitable for determining trace CAP in real samples.
