Abstract
A label-free electrochemical aptasensor was fabricated to sensitively determine malachite green (MG) based on Au nanoparticles/graphene quantum dots-tungsten disulfide nanosheet composite film modified glassy carbon electrode (AuNPs/GQDs-WS2/GCE). A facial strategy for the self-assembly of graphene quantum dots (GQDs) on tungsten disulfide nanosheets (WS2) was developed to fabricate 0D/2D nanocomposites. As-prepared GQDs-WS2 hybrids exhibited significantly enhanced electrocatalytic properties, and were first used as electroactive materials to construct electrochemical aptasensor. The AuNPs/GQDs-WS2/GCE was prepared through depositing Au nanoparticles on the surface of the GQDs-WS2 film, which acted as the electrochemical sensing matrix to covalently immobilize the aptamers of MG via the Au–S bond. In this label-free proposal, the aptasensor was applied to detect MG by monitoring voltammetric signal resulted from electrochemical oxidation of the MG captured by the aptamer. Under the optimized conditions, the aptasensor showed a wide linear range from 0.01 to 10 μM for MG detection with a low detection limit of 3.38 nM (S/N = 3). The method was applied to determination of MG in spiked fish samples and gave satisfactory results.
Highlights
Malachite green (MG) is a triphenylmethane dye which was widely applied in aquaculture because of its low cost and good antimicrobial activity [1]
Since 1990, many studies have showed that MG is highly toxic, mutagenic, and carcinogenic [2,3], which has been restricted or prohibited to be used as an antibacterial in fish farming due to potential hazards to human health resulting from its accumulation in aquatic products [4]
Numerous methods have been reported for determination of MG, including enzyme-linked immunosorbent assay (ELISA) [5], a fluorometry method [6], liquid chromatography–mass spectrometry (LC-MS) [7], and surface-enhanced resonance Raman scattering (SERS) [8]
Summary
Malachite green (MG) is a triphenylmethane dye which was widely applied in aquaculture because of its low cost and good antimicrobial activity [1]. We developed a new label-free electrochemical aptasensor based on nanocomposite film modified electrode for MG detection, which provided a facile, selective, sensitive, and fast voltammetric method for determining low concentrations of MG in fish samples. Among the various electroactive materials, good performance nanomaterials have been widely used because of excellent electrochemical properties such as high electronic conductivity and large specific surface area [17,18]. AAfftteerr MMGG wwaass ccaappttuurreedd bbyy tthhee aappttaammeerr dduuee ttoo tthhee ssppeecciifificc rreeccooggnniittiioonn rreeaaccttiioonn,, aa wweellll--ddeefifinneedd aannooddiicc ppeeaakk rreessuullttiinngg ffrroomm eelleeccttrroocchheemmiiccaall ooxxiiddaattiioonn ooff tthhee MMGG oonn tthhee mmooddiififieedd eelleeccttrrooddee aappppeeaarrss. The phosphate buffer (PB, 0.067 M) at diverse pH was prepared by Na2HPO4 and KH2PO4
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