the electrolyte. The complexation with all the ligand would stabilize the Au(I) oxidation state around the gold surface (Au+ + Cl- AuClsolid ) [30]. Note that Au(III) is generated at potentials above +1.3 V (vs. RHE) or +1.1 V (vs. AgCl) [31]. Thus, the oxidation peak is unlikely, as a result of oxidation of the gold electrode to Au(III). The oxidation peak at +0.65 V showed an increase within the peak height when AuNPs have been deposited around the surface in the bare Au electrode. Related behavior was also noted for the reduction peak, indicating the greater totally free concentration of Au(I) in the electrode. Right after the self-assembly of DTT on AuNPs (Au bond), the oxidation peak at +0.65 V was noticeably decreased, even decrease than that on the bare gold electrode (Figure 1A). In contrast, the CV showed a noticeable enhance in the present at +0.9 V (vs. AgCl) when the bare gold electrode modified by gold nanoparticles was topic to DTT. Collectively with the impedance measurement, as addressed later, such results evinced the formation of DTT on the gold surface. It was additional confirmed that the oxidation present at +0.9 V (vs. AgCl)terials 2021, 11, x FOR PEER REVIEWNanomaterials 2021, 11,5 of5 ofDTT on the gold surface. It was further confirmed that the oxidation existing at +0.9 V (vs. AgCl) decreased progressively with growing ACR concentration (Figure (Figure 1B). This observation was decreased gradually with growing ACR concentration 1B). This observation was then exploited for the detection of ACR working with thethe PAK1 custom synthesis DTT-AuNP modified gold electrode. then exploited for the detection of ACR working with DTT-AuNP modified gold electrode.Figure 1. (A) CV analysis of bare gold, AuNP-modified Au electrode, and DTT-AuNP modified Au electrode and also the Figure 1. the AuNP-DTT modified gold electrode. (B) The impact of various Sigma 1 Receptor web concentrations Au addition of ACR of (A) CV analysis of bare gold, AuNP-modified Au electrode, and DTT-AuNP modifiedof ACR around the electrode and (AuNP-modified Au electrode without having analyte). gold electrode. (B) The impact of difmodified electrode; Blankthe addition of ACR of the AuNP-DTT modified The observed current decreased with increasing ferent concentrations of ACR on the modified electrode; Blank (AuNP-modified Au electrode withACR concentrations. out analyte). The observed present decreased with rising ACR concentrations.three.two. Qualities with the Bare Au Electrode 3.2. Characteristics of the Bare Au Electrode As anticipated, bare Au was the least heterogeneous, as illustrated by the SEM microAs anticipated, bare (Figures the least3A). along with the WSxMillustrated its AFM micrograph estimated an 16 Nanomaterials 2021, 11, x FOR PEER Evaluation 6 of graphs, Au was 2A and heterogeneous, as tool from by the SEM micrographs, (Figureaverage surface roughnessthe 0.03 .tool from its AFM micrograph esti2A and Figure 3A). and of WSxM mated an average surface roughness of 0.03 m DPV, with an initial possible of -0.five V to the end potential of +1.1 V, was made use of with a step prospective of 0.005 V at 0.01 V/s. DPV with the bare electrode exhibited one single peak at +0.92 V, that is well-known because the oxygen evolution peak [32]. At this potential, the hydroxyl (OH.) radical formed in the course of water electrolysis is highly reactive to dimerize into hydrogen peroxide (H2O2), that is additional oxidized into the O2 molecule. The experiment was then carried out to investigate the DPV behavior of bare Au with DTT simply adsorbed on its electrode surface. The bare Au electrode with adsorbe