Impacts of Select Organic Ligands on the Colloidal Stability, Dissolution Dynamics, and Toxicity of Silver Nanoparticles

Abstract

Key understanding of potential transformations that may occur on silver nanoparticle (AgNP) surface upon interaction with naturally ubiquitous organic ligands (e.g., -SH (thoil), humic acid, or -COO (carboxylate)) is limited. Herein we investigated how dissolved organic carbon (DOC), -SH (in cysteine, a well-known Ag(+) chelating agent), and -COO (in trolox, a well-known antioxidant) could alter the colloidal stability, dissolution rate, and toxicity of citrate-functionalized AgNPs (citrate-AgNPs) against a keystone crustacean Daphnia magna. Cysteine, DOC, or trolox amendment of citrate-AgNPs differentially modified particle size, surface properties (charge, plasmonic spectra), and ion release dynamics, thereby attenuating (with cysteine or trolox) or promoting (with DOC) AgNP toxicity. Except with DOC amendment, the combined toxicity of AgNPs and released Ag under cysteine or trolox amendment was lower than of AgNO3 alone. The results of this study show that citrate-AgNP toxicity can be associated with oxidative stress, ion release, and the organism biology. Our evidence suggests that specific organic ligands available in the receiving waters can differentially surface modify AgNPs and alter their environmental persistence (changing dissolution dynamics) and subsequently the toxicity; hence, we caveat to generalize that surface modified nanoparticles upon environmental release may not be toxic to receptor organisms.

Antibacterial activity of silver nanoparticles: A surface science insight

“…In an optic of standardization, most studies internationally are performed using DOM (or purified humic acid or fulvic acid fractions) obtained from the Suwannee River [130][131][132]. These fractions have been shown to adsorb at the surface of nanoparticles, causing their aggregation [130,133] and limiting their Ag + release [97]. Humic acid has also the capability to immobilize Ag + ions and is a mild reducer, leading to the formation of new Ag NPs after dissolution of the original ones [134][135][136], with influences on the Ag + release dynamics.…”

Speciation analysis of silver sulfide nanoparticles in environmental waters by magnetic solid-phase extraction coupled with ICP-MS

“…Humic acid. Since NPs can be stabilized by interaction with the dissolved organic matter such as humic acid that is common in the environmental waters, 38,39 it is essential to investigate the potential effects of humic acid on the extraction efficiency. As shown in Fig.…”

Investigating the versatility of multifunctional silver nanoparticles: preparation and inspection of their potential as wound treatment agents

“…Thus, it is important to select a ligand that is physically suitable in preventing the agglomeration of the silver ions at the nano-level by acting as a stabilizing agent. Pokhrel et al reports that certain organic ligands with the ability to receive waters are able to differentially modify the surface of silver nanoparticles and alter their environmental persistence [29]. Silver nanoparticles are stabilized electrostatically, sterically, and electrosterically [30].…”