Investigation of L-Tryptophan Electrochemical Oxidation with a Graphene-Modified Electrode.

Florina Pogacean, Codruta Varodi, Maria Coros, Irina Kacso, Teodora Radu, Bogdan Ionut Cozar, Valentin Mirel, Stela Pruneanu

Biosensors 2021 Jan 28

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A graphene sample (EGr) was prepared by electrochemical exfoliation of graphite rods in solution containing 0.05 M (NH4)2SO4 + 0.1 M H3BO3 + 0.05 M NaCl. The exfoliation was performed by applying a constant voltage (12 V) between the graphite rods, while the temperature was kept constant (18 °C) with a temperature-controlled cryostat. The structural investigation of the graphene sample, performed by X-ray powder diffraction (XRD), revealed that the sample consists of a mixture of few-layer (69%), multi-layer graphene (14%) and graphene oxide (17%). In addition, XPS analysis proved that the sample was triple-doped with heteroatoms such as nitrogen (1.7 at%), sulfur (2.5 at%), and boron (3 at%). The sample was deposited onto the surface of a clean, glassy carbon electrode (GC) and investigated for the non-enzymatic electrochemical detection of L-tryptophan (TRP). The electrocatalytic properties of the EGr/GC electrode led to a considerable decrease in the oxidation potential from +0.9 V (bare GC) to +0.72 V. In addition, the EGr/GC electrode has higher sensitivity (two times) and a lower detection limit (ten times) in comparison with the bare GC electrode.

Citation

Florina Pogacean, Codruta Varodi, Maria Coros, Irina Kacso, Teodora Radu, Bogdan Ionut Cozar, Valentin Mirel, Stela Pruneanu. Investigation of L-Tryptophan Electrochemical Oxidation with a Graphene-Modified Electrode. Biosensors. 2021 Jan 28;11(2)