Enhanced Stability, Conductance, and Catalytic Activity of Gold Nanoparticles via Oxidative Dissolution by KMnO₄

Abstract

The present paper reports the oxidative etching of Au nanospheres by an oxidant, KMnO 4 , which resulted in the formation of new particles of different reduced sizes from single starting nanoparticles. The significant blue-shifting (536 ! 527 nm) of the surface plasmon band for Au nanospheres was observed due to their size alterations after oxidative dissolution of Au 0 to Au þ3 . This was supported by the cyclic voltammetry studies, which revealed an anodic peak at À0.90 V in agreement with the standard electrode potential of Au 0 =Au þ3 (À0.96 V). Dynamic light scattering (DLS) analysis showed that the hydrodynamic diameter of Au nanospheres ($41 nm) was decreased from $26 to 4 nm as a function of KMnO 4 concentration, as further evidenced by TEM. This oxidation-driven process resulted in colloids with higher zeta potential, conductance, and enhanced catalytic activity ($2 times) than their bare nanoparticles for the reduction of p-nitrophenol to p-aminophenol attributed to the higher surface area-to-volume ratio.

Amphipathic dendritic poly-peptides carrier to deliver antisense oligonucleotides against multi-drug resistant bacteria in vitro and in vivo

“…DLS results showed that the size of DP-AD were 130–150 nm, showing a narrow distribution with the polydispersity index (PDI) less than 0.4, which were larger than the values measured by TEM (60–80 nm) (Fig. 1 e and Additional file 1 : Table S4), consistent with the previous evidences attesting that the hydrodynamic diameters measured by DLS were larger than the solid diameters measured by TEM [ 34 , 35 ]. Notably, DLS and TEM results of the linear DP-AD (L-DP-AD) were consistent with those of DPP7 (Fig.…”

Amphipathic Dendritic Poly-peptides Carrier to Deliver Antisense Oligonucleotides Against Multi-drug Resistant Bacteria in Vitro and in Vivo

“…DLS results showed that the size of DP-ADs were 130-150 nm, showing a narrow distribution, which were larger than the values measured by TEM (60-80 nm) (Fig. 1e and Additional le 1: Table S4), consistent with the previous evidences attesting that the hydrodynamic diameters measured by DLS were larger than the solid diameters measured by TEM [34,35]. Notably, DLS and TEM results of the linear DP-AD (L-DP-AD) were consistent with those of DPP7 (Fig.…”

On the Effect of Modified Carbohydrates on the Size and Shape of Gold and Silver Nanostructures

“…As an illustrative study, selected Au and Ag NPs were tested for stability against protein corona formation, ionic strength, potassium permanganate, and penicillamine (results are shown in Supplementary information, Figures S8 and S9 ). The results revealed that both Au and Ag NPs resisted protein corona formation while potassium permanganate triggered re-formation of the NPs (based on SPR peaks) as expected [ 26 ]; the absorption peak belonging to KMnO 4 disappeared within 6 h of incubation due to its consumption. High concentrations of NaCl decreased the intensity of the SPR peak, which is ascribed to the precipitation of Au and Ag NPs (even though it was minimal) with increased ionic strength, thus reducing the intensity of plasmon absorption.…”