l-Phenylalanine-Imprinted Electrochemical Sensor Based on WS₂ Nanoflowers on N,B-Doped Graphene and Its Application to Milk Samples

Phenylketonuria (PKU) is a critical disease in the disorder of amino acid metabolism, which mostly emerges in children. The most common method used in PKU treatment is the detection of l-phenylalanine (PHEA) as the biomarker of PKU. In the present work, a new molecularly imprinted electrochemical electrode based on WS2 nanoflowers (NFs) on N,B-doped graphene (WS2 NFs/N,B-GR) is presented for PHEA assay in milk samples. First of all, WS2 NFs/N,B-GR was synthesized via a high-efficiency hydrothermal synthesis. Cyclic voltammetry was applied to the electrochemical cell, including PHEA as a template molecule and pyrrole as a monomer, to form PHEA-imprinted electrochemical electrodes. Then, the structural and morphological features of WS2 NFs and WS2 NFs/N,B-GR were investigated in detail by various analytical methods. The limit of quantification and limit of detection values were obtained as 1.0 × 10–11 and 3.0 × 10–12 M, respectively, by a PHEA-imprinted electrochemical electrode. Finally, a PHEA-imprinted electrochemical sensor having a high degree of selectivity, stability, and reusability is presented in the literature for early diagnosis of PKU.