Electrochemical Sensing of Neurotoxic Agents Based on Their Electron Transfer Promotion Effect on an Au Electrode

Abstract

An electrochemical molecular sensor based on a new principle is reported. Nereistoxin (NRT, 4-N,N-dimethylamino-1,2-dithiolane), a naturally occurring neurotoxin (nicotinic acetylcholine receptor agonist), was adsorbed on an Au electrode via Au-S covalent bonding and accelerated the electron transfer between the electrode and the marker, ferricyanide anion. The contrast between the electrochemical responses obtained with the bare and NRT-modified Au electrodes was more pronounced at a low ionic strength of the supporting electrolyte, KCl. In the presence of 1 mM KCl, almost a 0/1 contrast between the signals was obtained through electrostatic interaction between the protonated tertiary amino group of NRT and the anionic ferricyanide ion. No current was observed with an electrode modified with mercaptopropionic acid. An unusually low ionic strength thickened the electric double layer to the degree where current was not observed with the bare electrode. The effect of the electrostatic concentration of the marker ion becomes obvious under such conditions. Commercially available NRT-related pesticides such as Cartap and Bensultap were also detected using the same format after pretreatments by hydrolysis/reduction. The present sensing method was successfully applied to human serum with satisfactory sensitivity.

Electrochemical analysis of anionic analytes in weakly supported media using electron transfer promotion effect: a case study on nitrite

“…Therefore, analytes with a low concentration can diffuse on the electric double layer 23 . While the electron transfer of nitrite ions in the absence of NTX decreases by this effect, the positively charged amino group on the NTX provides a potential gradient on the electrode surface, similar to the one obtained in a typical concentration of the supporting electrolyte 33 . Furthermore, through an electrostatic interaction, this positively charged NTX leads to the concentration of nitrite ions near the surface, as shown in Fig.…”

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

“…Several methods of nereistoxin detection utilize the notable structural peculiarity of its molecule disulfide bond and its ability to react with gold. Specifically, quantum dots/gold nanoparticles fluorescent assay [ 50 , 51 ], electrochemical sensing based on transfer promotion effect on gold electrodes [ 52 , 53 ], and gold nanoparticles colorimetric assay [ 54 ] or DNA-switches [ 55 ] are selective nereistoxin (and its analogs) techniques, enabling fast and sensitive detection in the environment. It is interesting to note that varacin, a marine phenylethylamine derivative with an unusual sulfur-containing ring ( Figure 1 ), has shown nAChR antagonistic properties at medium micromolar concentrations ( Table 1 ) in one of our previous works [ 13 ].…”

Electrochemical Enzyme Sensor Based on the Two-Dimensional Metal–Organic Layers Supported Horseradish Peroxidase

“…Chemically modified electrodes (CMEs) were proposed to solve this problem by optimizing the molecular orientations of HRP on CMEs by the surface charge or nanostructures as well as by facilitating the conductive network of electron transfer [ 4 , 5 ]. For example, the protonated amino groups are usually grafted on the CMEs surface to provide the electrostatic microenvironment for the molecular orientation of HRP since it is overall negatively charged [ 6 ]; and the metal nanoparticles [ 7 ], carbon nanotubes [ 8 ], and graphene [ 9 , 10 ] were adopted as current collectors to form the electron transfer network.…”