A novel electrochemical biosensor based on Fe₃O₄ nanoparticles-polyvinyl alcohol composite for sensitive detection of...

In this research, a new electrochemical biosensor was constructed for the glucose detection. Iron oxide nanoparticles (Fe₃O₄) were synthesized through co-precipitation method. Polyvinyl alcohol-Fe₃O₄ nanocomposite was prepared by dispersing synthesized nanoparticles in the polyvinyl alcohol (PVA) solution. Glucose oxidase (GOx) was immobilized on the PVA-Fe₃O₄ nanocomposite via physical adsorption. The mixture of PVA, Fe₃O₄ nanoparticles and GOx was drop cast on a tin (Sn) electrode surface (GOx/PVA-Fe₃O₄/Sn). The Fe₃O₄ nanoparticles were characterized by X-ray diffraction (XRD). Also, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) techniques were utilized to evaluate the PVA-Fe₃O₄ and GOx/PVA-Fe₃O₄ nanocomposites. The electrochemical performance of the modified biosensor was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Presence of Fe₃O₄ nanoparticles in the PVA matrix enhanced the electron transfer between enzyme and electrode surface and the immobilized GOx showed excellent catalytic characteristic toward glucose. The GOx/PVA-Fe₃O₄/Sn bioelectrode could measure glucose in the range from 5 × 10^-3 to 30 mM with a sensitivity of 9.36 μA mM^-1 and exhibited a lower detection limit of 8 μM at a signal-to-noise ratio of 3. The value of Michaelis-Menten constant (K_M) was calculated as 1.42 mM. The modified biosensor also has good anti-interfering ability during the glucose detection, fast response (10 s), good reproducibility and satisfactory stability. Finally, the results demonstrated that the GOx/PVA-Fe₃O₄/Sn bioelectrode is promising in biosensor construction.