Amperometric glucose biosensor based on immobilization of glucose oxidase on a magnetic glassy carbon electrode modified with a novel magnetic nanocomposite

- A novel multilayer nanocomposite Ag@MWCNT-IL-Fe3O4 was reported for fabrication of third generation glucose biosensor.
- Biosensor showed very good performance at aerated and deaerated solutions.
- The proposed biosensor showed an extended linear range and lower detection limits.
- The developed biosensor had an excellent efficacy for the determinations of glucose in the real samples.

We present a method to produce a magnetic glassy carbon electrode (MGCE) modified with multilayer nanocomposite (Ag@MWCNT-IL-Fe3O4) as an immobilization support to promote electron transfer reactions of glucose oxidase (GOx). The nanocomposite verified by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and a vibrating sample magnetometer (VSM). The direct electron transfer (DET) between GOx and Ag@MWCNT-IL-Fe3O4 nanocomposite was investigated using cyclic voltammetry which showed a pair of well-defined redox peaks corresponding to redox active center of GOx. Utilization of constructed electrode for detection of glucose was studied in N2 and air saturated solutions (pH 7.0). The GOx/Ag@MWCNT-IL-Fe3O4/MGCE showed excellent stability, a detection limit of 2.12 μM, a linear range between 6 μM and 2 mM, and a dynamic range up to 2.7 mM at the air saturated solutions. Also, in N2 saturated solutions (pH 7.0), determination of glucose was carried out by amperometry, and the proposed biosensor showed good reproducibility and stability with a detection limit of 3.8 μM and a linear range between 10 μM and 1 mM. Such analytical performances confirm that the fabricated biosensor used in this work has potential to be applied for development of redox enzyme based biosensors.

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