Simultaneous Analysis of Hydroquinone, Arbutin, and Ascorbyl Glucoside Using a Nanocomposite of Ag@AgCl Nanoparticles, Ag2S Nanoparticles, Multiwall Carbon Nanotubes, and Chitosan.

Nutthaya Butwong,John H T Luong,Thidarat Kunawong

doi:10.3390/nano10081583

Nutthaya Butwong, John H T Luong + Show 1 more

Open Access

https://doi.org/10.3390/nano10081583

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Abstract

A nanocomposite comprising Ag nanoparticles on AgCl/Ag2S nanoparticles was decorated on multi-walled carbon nanotubes and used to modify a glassy carbon electrode. Chitosan was also formulated in the nanocomposite to stabilize Ag2S nanoparticles and interact strongly with the glucose moiety of arbutin (AR) and ascorbyl glucoside (AA2G), two important ingredients in whitening lotion products. The modified electrode was characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) and cyclic voltammetry and used for the simultaneous analysis of hydroquinone (HQ), AR, and AA2G. The electrode showed excellent electrocatalysis towards the analytes by shifting the anodic peak potential to a negative direction with ≈5-fold higher current. The sensor displayed a linearity of 0.91–27.2 μM for HQ, 0.73–14.7 μM for AR, and 1.18–11.8 μM for AA2G, without cross-interference. A detection limit was 0.4 μM for HQ, 0.1 μM for AR, and 0.25 μM for AA2G. The sensor was applied to determine HQ, AR, and AA2G spiked in the whitening lotion sample with excellent recovery. The measured concentration of each analyte was comparable to that of the high performance liquid chromatographic (HPLC) method.

Highlights

Melanin is synthesized from tyrosine by tyrosinase to form two eumelanins or one pheomelanin in the absence or presence of cysteine, respectively
Synthesized Ag2S nanoparticles exhibited an average size of ≈3–5 nm as estimated by transmission electron microscopy (TEM) micrographs (Figure S1) and a negative charge, i.e., they were virtually free from Ag+ (Figure S2)
The morphologies of Ag@AgCl/Ag2S located inside or outside of the carbon nanotubes (CNTs) were investigated by TEM imaging (Figure 1a)

Summary

Introduction

Melanin is synthesized from tyrosine by tyrosinase to form two eumelanins (brown to black) or one pheomelanin (yellow to red) in the absence or presence of cysteine, respectively. Commercial skin lightening products are formulated with a mixture of tyrosinase inhibitors including ascorbyl glucoside (AA2G) and hydroquinone-O-β-D-glucopyranoside (β-arbutin, AR). Popular AR is widely used in the beauty industry as depigmenting cosmetics and anti-sunburn of human skin. The cosmetic effect of AR, a glycosidic form of hydroquinone, is weaker than hydroquinone but exhibits lower cytotoxicity, nephrotoxicity, and genotoxicity. AR undergoes hydrolysis to release hydroquinone (HQ) when it is subject to high temperature, ultraviolet (UV) radiation, dilute acid, or human skin bacteria [1]. Both kojic acid and alpha hydroxy acid are allowed in cosmetics in Europe, but hydroquinone and tretinoin are prohibited. Monitoring cosmetic ingredients with hydroquinone and ascorbic derivatives is essential to ensure product quality and consumer safety [2]

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