The direct electrochemistry and bioelectrocatalysis of nitrate reductase at a gold nanoparticles/aminated graphene sheets modified glassy carbon electrode

Abstract

It is rather difficult to achieve the direct electrochemistry of nitrate reductase (NR) as it is a complex homodimeric enzyme. However, in this study, the direct electron transfer between NR's redox centers and the electrode surface was achieved with the aid of aminated graphene sheets (am-GSs) which could immobilize NR stably and control the orientation of the enzyme molecules on the surface of the modified electrode through electrostatic attractions. Moreover, when the gold nanoparticles (AuNPs) which could act as electronic wire were introduced to the modified electrode, the NR-based enzymatic reduction of nitrate was promoted and a sensitive electrochemical response regarding the electrochemical reduction of nitrate could be obtained at the NR/AuNPs/am-GSs/GC electrode. Under optimized conditions, a wide linear range from 1.0 Â 10 À6 mol L À1 to 2.0 Â 10 À3 mol L À1 was acquired with a low detection limit of 7 Â 10 À7 mol L À1 (S/N ¼ 3). The biosensor was successfully employed to determine the total nitrogen in environmental water samples and the results were in good accordance with those obtained by ultraviolet-visible spectrophotometry.As the isoelectric point of NR is 6.2, 31 if dissolving the enzyme in 0.1 mol L À1 PBS with pH value of 7.0, NR will be negatively 37208 | RSC Adv., 2019,9,[37207][37208][37209][37210][37211][37212][37213] This journal is

Engineering Electro- and Photocatalytic Carbon Materials for CO2 Reduction by Formate Dehydrogenase

“…The immobilization of enzymes on modified electrodes ( Figure 1 a,b) 31 provides an electrochemical tool to probe the activity of enzyme films (catalytic current) as a function of applied potential, material surface chemistry, and external chemical components (buffers, SEDs, redox mediators), which can guide the improvement in the performance of a photocatalytic support with an analogous surface. W-FDH from Dv H has previously displayed DET activity on positively charged amine-modified graphite 32 and Au 33 electrodes, but an in-depth understanding of the enzyme–electrode interface and the extension of this observation to photocatalytic materials have not yet been reported ( Figure 1 a,c).…”

“…Although engineering the material surface is important to realize improvements in activity via optimized physical adsorption, 28 auxiliary photocatalytic components such as the sacrificial electron donor (SED) and buffer components may also perturb the electrostatic enzyme−material interface, preventing the biohybrid systems from matching the intrinsic enzyme activity. 29,30 The immobilization of enzymes on modified electrodes (Figure 1a,b) 31 provides an electrochemical tool to probe the activity of enzyme films (catalytic current) as a function of applied potential, material surface chemistry, and external chemical components (buffers, SEDs, redox mediators), which can guide the improvement in the performance of a photocatalytic support with an analogous surface. W-FDH from DvH has previously displayed DET activity on positively charged amine-modified graphite 32 and Au 33 electrodes, but an in-depth understanding of the enzyme−electrode interface and the extension of this observation to photocatalytic materials have not yet been reported (Figure 1a,c).…”

Electrodeposition of Copper Thin Films on Screen Printed Carbon Electrodes towards Electrochemical Sensing of Nitrate

“…22 Ion selective electrodes (ISEs) operating in potentiometric mode for are also developed for NO 3 − ion sensing. 23 Bioinorganic metal complexes and nanostructures mimicking the action of enzymes (nanozymes) are particularly effective in electrochemical detection of NO 3 − due to their large surface area, good thermal stability and electrical conductivity. A wide range of metallic nanostructures (Ag, Au, Cu, Pd, Pt, and Ni) are widely explored to create non-enzymatic electrochemical sensors for NO 3…”