Development and Evaluation of Copper Electrodes, Modified with Bimetallic Nanoparticles, to be Used as Sensors of Cysteine-Rich Peptides Synthesized by Tobacco Cells Exposed to Cytotoxic Levels of Cadmium

Abstract

We report on two new electrochemical sensors which, coupled to differential pulse voltammetry, constitutes a useful tool for diagnosis of heavy metal pollution. The electrochemical sensors AgHgNf/Cu and the AgBiNf/Cu were obtained by deposition of bimetallic particles of AgHg or AgBi on copper electrodes covered with a Nafion (Nf) film, respectively. Micrographs of the electrode’s surface showed evenly scattered bimetallic particles, with an approximate diameter of 150 nm, embedded in the Nafion (Nf) film. In order to test the electrodes, the hydrogen evolution signal according to the Brdička reaction was measured for the determination of cysteine-rich peptides (CRp) produced by plants. To check the accuracy of the electrodes, real samples of Nicotiana tabacum cells exposed to cytotoxic levels of cadmium were tested. The AgHgNf/Cu electrode produced detection limits (DLs) of 0.088 µmol L−1 for Cysteine and 0.139µmol L−1 for Glutathione, while for the AgBiNf/Cu electrode DLs were 0.41 µmol L−1 for cysteine and 0.244 µmol L−1 for glutathione. Thus, the new electrodes could be a useful analytical electrochemical system very convenient for fieldwork. The electrodes were capable of direct, accurate, and sensitive detection of synthesized peptides, despite the complex matrix where the Nicotiana tabacum cells were grown.

Simultaneous quantification of Cd(II) and Pb(II) in surface marine sediments using Ag–Hg and Ag–Bi nanoalloys glassy carbon modified electrodes

“…According to Brett et al. [ 18 ], the structure of polymer-coated in HgNfNysNf composite should be considered as we have corroborated [ 15 ]. The nanoparticles mercury at the AgHgNfNysNf-GC modified electrode could be a collection of nano-droplets, closely spaced.…”

“…At bare GC electrode (curve a), the electron transfer resistance (Rct) at high frequency is smaller than that of the modified electrodes. Nf immobilization at the GC (curve b) produced a larger semicircle, which can be due to the limitations imposed to charge transfer by the polymer coating [ 15 , 17 ]. When the bimetallic deposits were formed at the Nf/GC modified electrodes, this has an interesting effect on the shape of the impedance plots and Rct values ( Figure 2 b-c).…”

“…Precision measurements of these modified electrodes were reported in previous works [ 14 , 15 ]. The relative standard deviation (RSD) values of the twenty consecutive determinations of each metal indicated very good precision values range from 1 to 4 [ 30 ], meaning that the electrodes are mechanically very resistant and the surface modifying Nf film is strongly adhered to the GC electrode.…”

“…Previously reported procedure was followed [ 14a , 14b , 15 ]: GC electrodes were firstly polished using number 2000 sandpaper and afterward using spreads of aluminium oxide powder, with decreasing particle size 1.0 μm, 0.3 μm and 0.05 μm, on a billiard table cloth. After polishing, the GC electrode was submerged in an ultrasonic bath containing distilled/deionized water for 5 min to get rid of any aluminium oxide particle loosely adhered to the GC.…”

Recent Advances in Electrochemical Sensors for Sulfur-Containing Antioxidants

“…Recently, bimetallic NPs have received attention as a more effective modifier due to the synergetic effect of each metal [ 63 , 64 , 65 , 66 , 67 , 95 ]. The electrocatalytic performance parameters can be varied through controlling the size, composition, morphology, and crystal structure of the nanoparticles [ 95 ].…”