Triclosan is linked to several side effects, including potential carcinogenicity, making its measurement in personal care products crucial for consumer safety [1]. Herein, a low-cost disposable electrochemical sensor has been introduced based on a thin gold chip substrate (GCHIP) modified with gold-silica core-shell nanostructures (AuNPs@SiO2) to detect and determine triclosan in real samples. To achieve the purpose, AuNPs was first prepared according to a modified Turkevich method and subsequently modified with polyvinylpyrrolidone (PVP). Next, the silicate shell was formed using tetraethoxysilane (TEOS) as a crosslinker and 3-(Trimethoxysilyl)propyl methacrylate (MPS) as a monomer via the sol-gel process. AuNPs@SiO2 nanostructures were then characterized by Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopies, transmission electron microscopy (TEM), and water contact angle (WCA) measurement. Moreover, the morphology and surface characteristics of the AuNPs@SiO2/GCHIP sensor were investigated using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), as well as energy-dispersive x-ray (EDX) spectroscopy. Thereafter, the factors affecting the analytical performance of the sensor were optimized to achieve the maximum sensitivity. The calibration plot was constructed using square wave voltammetry (SWV), which showed to be linear in the concentration range of 1 to 100 μM. The limits of detection (LOD) and quantification (LOQ) were obtained to be 0.5 and 2 μM, respectively. Also, the reproducibility of the method expressed as %RSD was 4%. Eventually, to prove the applicability of the sensor for real sample analysis, the amount of triclosan in unspiked and spiked toothpaste sample was determined which showed a recovery of 93%. The proposed sensor has merits of simplicity, portability, and cost-effectiveness.

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