Synthesis of Gadolinium-Doped Molybdenum Diselenide Nanospheres for Ultrasensitive Electrochemical Determination of Essential Amino Acid in Human Serum and Milk Samples

The electrocatalytic activity and electronic conductivity of 2D transition metal chalcogenides are usually enhanced by as follows the ideal strategy such as doping or substitution heterogeneous atoms. Here, a rare Earth metal ion of gadolinium (Gd³⁺) was doped with MoSe₂ and synthesized through the hydrothermal method. The morphology and nanostructure of Gd³⁺ with MoSe₂ spheres were analyzed under X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron, High-resolution transmission electron microscopy analysis, Field emission scanning electron microscopy, and energy-dispersive spectroscopy. Furthermore, the Gd³⁺ doped MoSe₂ sphere modified glassy carbon electrode (Gd@MoSe₂/GCE) was used for the sensing of tryptophan. The Gd@MoSe₂ modified GCE shows remarkable sensing performance of tryptophan resulting in a linear range (20 nM–220 μM) with a low detection limit (6.7 nM). Under the optimal condition, the developed electrochemical sensor was successfully used to determine tryptophan (TRP) in blood serum and milk samples. The electrochemical biosensing results suggest that the doping of the Gd³⁺ doped MoSe₂ sensor is a promising electrocatalyst in biological and food samples.