Electrochemical mechanism of rusticyanin (Rus.) isolated from A. ferrooxidans measured by Rus.-ZnS-QDs/L-Cys/Au electrode

Abstract

Electrochimcal behaviors of rusticyanin (Rus.) isolated from Acidithiobacillus ferrooxidans were investigated through Rus.-ZnS-QDs/L-Cys/Au electrode. The cyclic voltammetric results indicate that rusticyanin immobilized on the surface of Rus.-ZnS-QDs/L-Cys/Au electrode can undergo a direct quasi-reversible electrochemical reaction. The immobilized rusticyanin is not denatured and still retains its activity in the temperature range of 19−43 °C. The reduction ability of the protein increases and its oxidation ability becomes weak with the increase of pH from 6.0 to 7.8. Fe 2+ ions in the solution can promote the electron transfer kinetics of the immobilized rusticyanin and make its peak potentials (φ p ) markedly move negatively.

A conventional symmetric biosupercapacitor based on rusticyanin modified gold electrodes

“…Contrary to previous studies of the immobilized protein, in which cathodic peaks of bare electrodes (Au and ZnS quantum dots modified Au electrodes without Rc) were observed with peak potentials and currents close to the cathodic peak of the immobilized protein ( Fig. 4a in [29]), no pronounced electrochemical signals on non-biomodified electrodes were registered by us (Fig. 2).…”

“…[10]), with protonation/deprotonation of accessible residues (non-faradaic term [37]) contributing to a lesser extent to the overall capacitance. However, as mentioned above, there is only one report in the literature regarding electrochemistry of immobilized Rc [29]. In that report, quantum dots…”

“…Refs. [28,29]. While Alcaraz with co-workers carried out electrochemical investigations of the protein in solution [28], the only paper regarding electrochemistry of immobilized Rc, viz.…”

“…Ref. [29], contains several contentious issues, which raise some doubts regarding the direct electric wiring of the protein to the electrode surface (vide infra). Thus, we begin our paper with detailed spectroelectrochemical studies of free and immobilized Rc, as the fundamental basis for its practical applications in bioelectronics.…”

Sensitive determination of catechol using a glassy carbon electrode modified with l-cysteine and ZnS:Ni/ZnS quantum dots

“…19,20 L-Cys has used to immobilized enzyme, DNA or other substances widely because of its -SH and -NH 2 groups. [21][22][23][24] Quantum dots (QDs) including a number a nanoparticles composed by IIA-VIA semiconductors or IIIA-VA semiconductors. 25,26 Based on the analyte-induced changes in luminescence, QDs have been reported over the past decade for optical sensing of various ions and small molecules.…”