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Monitoring of high intensity artificial sweeteners in the food industry for environmental and human health has become relevant in recent years. This work exploits the electrocatalytic properties of the laccase enzyme for sensing of a high intensity sweetener sucralose experimentally and supported by computational modeling. The fabrication of the laccase biosensor was achieved using laccase immobilized onto zinc oxide nanoparticles (ZnONPs) capped with p-amino thiophenol (ATP) and covalently attached to graphene oxide (GO) modified glassy carbon electrode (Lac/ZnONPs-ATP-GO/GCE). The developed biosensor exhibited an 8-fold enhancement of differential pulse voltammetry signals compared with the bare GCE at pH 5.0 in a 0.1 M phosphate buffer. The amplification of signals was due to a firm binding of laccase onto the surface of GO through high isoelectric point ZnONPs, exhibiting an enzymatic catalytic activity towards the oxidation of sucralose (SUC) at + 0.25 V (vs. Ag/AgCl). Under the optimized experimental conditions, the anodic peak current linearly increased with the sucralose concentrations ranging from 0.025–0.1 mM (R2 = 0.9984) and 0.25–1.0 mM (R2 = 0.9979) with a detection limit (S/N = 3) of 0.32 μM. Furthermore, the proposed strategy was confirmed by assessing the interactions between the sucralose and the laccase using computational tools. First, the density functional theory (DFT) calculations of SUC revealed a HOMO–LUMO energy gap of − 0.2555 eV, suggesting a great tendency to act as an electron donor. Furthermore, adsorption and sucralose-laccase docking studies were carried out to better understand the redox mechanisms. These results revealed that SUC forms hydrogen bonds with ILE 230 and GLN 228 and other amino acids of the hydrophobic channel of the binding sites, thereby facilitating the redox reaction for the detection of sucralose.

A highly sensitive and novel electrochemical sensor for the detection of neotame using differential pulse voltammetry with a modified glassy carbon electrode is presented. The method was further customized by the fabrication of the electrode surface with copper nanoparticles-ammonium piperidine dithiocarbamate-mutiwalled carbon nanotubes assimilated with β-cyclodextrin. The multiwalled carbon nanotubes assimilated with β-cyclodextrin/glassy carbon electrode exhibited catalytic activity towards the oxidation of neotame at a potential of 1.3 V at pH 3.0. The transmission electron microscopy, thermogravimetric analysis, frontier transform infrared spectroscopy and cyclic voltammetry were employed to characterize the electrochemical sensor. The sensitivity and detection limits of the electrode increased two-fold in contrast to the β-CD-MWCNTs/GCE sensor. The developed method was successfully applied for the determination of neotame in food samples, with results similar to those achieved by our modified capillary electrophoresis method with a 96% confidence level.

An electrokinetic chromatographic method was developed for the chiral separation of neotame, a new high intensity artificial sweetener, using a chiral separating agent heptakis 2,3,6-tri-o-methylbetacyclodextrin. The purpose of this study was to better understand diastereomer-resolution interactions between neotame and the chiral separating agent. Molecular docking studies were performed to elucidate the mechanism of the separation. The optimum conditions were 50 mM phosphate buffer, pH 5.5, applied voltage 20 kV, cassette temperature of 30°C, and a 4 s sample injection time. The calibration curve showed good linearity (r2 > 0.99) with recoveries for both diastereomers, ranging from 95.66–99.00% and the limits of detection for L,L-neotame and D,D-neotame were 0.01857 and 0.08214 mM, respectively. The developed method showed analytical precision with relative standard deviations (n = 5) of 1.20% and 1.17% with respect to migration time and peak area, respectively. A large difference in the interaction ener...