Electrochemical sensor for detection of tryptophan in the milk sample based on MnWO4 nanoplates encapsulated RGO nanocomposite

Abstract Tryptophan (TRY) is an essential amino acid associated with neurotransmitters and some particular syndromes. For that reason, the detection of Try levels in the food samples is necessary. In recent years electrochemical sensors exhibit inherent effect to detect the amino acids because it has more benefits such as high sensitivity, simplicity, celerity, and economy compared to other traditional methods. Some bimetal oxides have emerged as good candidates for the trace-level detection of amino acids due to their large surface area and high conductivity. As the carbon-based materials, importantly reduced graphene oxide (RGO) have large surface areas to increase the conductivity of the electrodes. In this present work, we demonstrate the detection of TRY by using an electrochemical sensor based on a bimetal oxide with RGO nanocomposite material. We synthesized a manganese tungstate-nanoplates-encapsulated reduced graphene oxide nanocomposite (MnWO4/RGO) using a facile hydrothermal method. Morphological and structural characterization of the nanocomposite MnWO4/RGO was performed using various spectroscopic techniques and analytical methods. The resulting MnWO4/RGO/GCE could be used for the quick and selective determination of TRY in the presence of other interfering bioanalytes. Under optimum conditions, this electrochemical sensor exhibited maximum performance toward TRY determination with good linearity in a broad linear range of 0.001–120 μM with a remarkable lower detection limit of 4.4 nM. The newly proposed sensor was used for the precise determination of TRY in milk samples with satisfactory results.