Modified Graphite Pencil Electrode Based on Graphene Oxide-Modified Fe₃O₄ for Ferrocene-Mediated Electrochemical Detection of Hemoglobin

Abstract

This study describes the synthesis of graphene oxide-modified magnetite (rGO/Fe3O4) and its use as an electrochemical sensor for the quantitative detection of hemoglobin (Hb). rGO is characterized by a 2θ peak at 10.03° in its X-ray diffraction, 1353 and 1586 cm–1 vibrations in Raman spectroscopy, while scanning electron microscopy coupled with energy-dispersive spectroscopy of rGO and rGO/Fe3O4 revealed the presence of microplate structures in both materials and high presence of iron in rGO/Fe3O4 with 50 wt %. The modified graphite pencil electrode, GPE/rGO/Fe3O4, is characterized using cyclic voltammetry. Higher electrochemical surface area is obtained when the GPE is modified with rGO/Fe3O4. Linear scan voltammetry is used to quantify Hb at the surface of the sensor using ferrocene (FC) as an electrochemical amplifier. Linear response for Hb is obtained in the 0.1–1.8 μM range with a regression coefficient of 0.995, a lower limit of detection of 0.090 μM, and a limit of quantitation of 0.28 μM. The sensor was free from interferents and successfully used to sense Hb in human urine. Due to the above-stated qualities, the GPE/rGO/Fe3O4 electrode could be a potential competitive sensor for trace quantities of Hb in physiological media.

Rational construction of micro-plate-like iron oxide/aluminium oxide-fabricated screen-printed carbon electrode for the electrochemical detection of the antiandrogen drug

“…33 Alternatively, the Raman bands at 250.1 and 509 cm −1 are attributed to the A 1g mode and assigned to the Fe-O vibrational stretching. 28,34 The stretching vibration band at 634.7 cm −1 is associated with the E g mode, corresponding to the Fe-O symmetric stretching vibration. The enhanced peak intensity at 1332.7 cm −1 is ascribed to the Al-O bond.…”