Voltammetric Study of the Influence of Various Phosphate Anions on Silver Nanoparticle Oxidation

Abstract

The antibacterial properties of silver are strongly controlled by the redox couple of silver/silver(I). This work reports the influence of phosphate anions on silver nanoparticle oxidation, which is important given the abundance of phosphate species in biological systems. The three different species of anions were found to have a varying degree of influence on silver oxidation with the order PO43−>HPO42−>H2PO4−. It was found that in the presence of phosphate anions, the silver oxidation potential shifts to a less positive value, which indicated the increasing ease of the oxidation reaction of silver. Given that the interplay between silver and its cation is crucial to its antibacterial properties and significant concentrations of the HPO42− anion are present at biological pH (near neutral), it is essential that the influence of the dibasic anion (HPO42−) on silver oxidation dynamics be considered for biological systems.

Bio-sourced phosphoprotein-based synthesis of silver-doped macroporous zinc phosphates and their antibacterial properties

“…In addition, better crystallization of Ag 0 was observed at 600 C, as indicated by the sharpening and higher intensity of the Ag peaks at 38.1 , 44.2 and 64.4 (2q). Another compound, which was probably silver zinc orthophosphate of the Ag 3 Zn 6 (-PO 4 ) 5 type (PDF 00-038-0302), crystallized at and above 600 C. This may result from either Ag nanoparticles that were oxidized by PO 4 3À species present in the sample, 53,54 as indicated by the decrease in the intensity of Ag peaks at 750 C, or silver atoms not involved in the crystallization of Ag 0 at temperatures of less than 600 C that participated in the crystallization of this new compound. Furthermore, in the absence of Ag in the starting mixture, the same zinc phosphate phases crystallized (i.e., a-Zn 3 (PO 4 ) 2 and gand a-Zn 2 P 2 O 7 , hopeite).…”

The oxygen reduction reaction at silver electrodes in high chloride media and the implications for silver nanoparticle toxicity

“…[26][27][28] All of those are sensitive to the local chemical environment. The oxidative dissolution of AgNPs in aqueous solution can be favoured by the presence of Cl À , I À and phosphate anions 29 although the release of Ag + can however simultaneously be inhibited by trace amounts of chloride due to formation of AgCl layers at the nanoparticle surface. 30 The combined anion effects inuencing both thermodynamics and kinetics hint at the complexity of silver nanotoxicology in natural media where, for example, it is observed that AgNPs are relative stable with less Ag + dissolution and ROS formed in environments such as authentic human saliva.…”

Electrochemical Detection and Characterization of Nanoparticles with Printed Devices

“…Furthermore, Au(III) species are only stable under some specific conditions; meanwhile, Ag(I) could be present as soluble species forming a complex or as the insoluble precipitate. The electrochemical response depends highly on the electrolyte medium [58,59], but this also offers more versatile experimental conditions where the AgNPs can be electrochemically oxidized by the direct method and could open the possibility to develop different tailored strategies for specific applications. As an opposite effect, AgNPs are usually less stable than AuNPs, are prone to aggregate in several media and, therefore, their use in applications, such as biosensing, is more challenging.…”