Design and Fabrication of Tryptophan Sensor Using Voltammetric Method

L-tryptophan is an amino acid that significantly impacts metabolic activity in both humans and herbivorous animals. It is also known as a precursor for melatonin and serotonin, and its levels must be regulated in the human body. Therefore, there is a need to develop a cost-effective, simple, sensitive, and selective method for detecting L-tryptophan. Herein, we report the fabrication of an L-tryptophan sensor using a nickel-doped tungsten oxide ceramic-modified electrode. The Ni-WO₃ was synthesized using simple strategies and characterized by various advanced techniques such as powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoelectron X-ray spectroscopy. Furthermore, a glassy carbon electrode was modified with the synthesized Ni-WO₃ and explored as the L-tryptophan (L-TRP) sensor. Cyclic voltammetry and differential pulse voltammetry were used to investigate the sensing ability of the modified electrode (Ni-WO₃/GC). The Ni-WO₃/GC exhibited an excellent limit of detection of 0.4 µM with a good dynamic linear range. The Ni-WO₃/GC also demonstrated excellent selectivity in the presence of various electroactive molecules. The Ni-WO₃/GC also showed decent reproducibility, repeatability, stability, and storage stability. This work proposes the fabrication of novel Ni-WO₃/GC for the sensing of L-tryptophan. So far, no report is available on the use of Ni-WO₃/GC for the sensing of L-TRP. This is the first report on the use of Ni-WO₃/GC for the sensing of L-TRP sensing applications.