Particle Coating-Dependent Interaction of Molecular Weight Fractionated Natural Organic Matter: Impacts on the Aggregation of Silver Nanoparticles

Abstract

Ubiquitous natural organic matter (NOM) plays an important role in the aggregation state of engineered silver nanoparticles (AgNPs) in aquatic environment, which determines the transport, transformation, and toxicity of AgNPs. As various capping agents are used as coatings for nanoparticles and NOM are natural polymer mixture with wide molecular weight (MW) distribution, probing the particle coating-dependent interaction of MW fractionated natural organic matter (M f -NOM) with various coatings is helpful for understanding the differential aggregation and transport behavior of engineered AgNPs as well as other metal nanoparticles. In this study, we investigated the role of pristine and M f -NOM on the aggregation of AgNPs with Bare, citrate, and PVP coating (Bare-, Cit-, and PVP-AgNP) in mono-and divalent electrolyte solutions. We observed that the enhanced aggregation or dispersion of AgNPs in NOM solution highly depends on the coating of AgNPs. Pristine NOM inhibited the aggregation of Bare-AgNPs but enhanced the aggregation of PVP-AgNPs. In addition, M f -NOM fractions have distinguishing roles on the aggregation and dispersion of AgNPs, which also highly depend on the AgNPs coating as well as the MW of M f -NOM. Higher MW M f -NOM (>100 kDa and 30−100 kDa) enhanced the aggregation of PVP-AgNPs in mono-and divalent electrolyte solutions, whereas lower MW M f -NOM (10−30 kDa, 3−10 kDa and <3 kDa) inhibited the aggregation of PVP-AgNPs. However, all the M f -NOM fractions inhibited the aggregation of Bare-AgNPs. For PVP-and BareAgNPs, the stability of AgNPs in electrolyte solution was significantly correlated to the MW of M f -NOM. But for Cit-AgNPs, pristine NOM and M f -NOM has minor influence on the stability of AgNPs. These findings about significantly different roles of M f -NOM on aggregation of engineered AgNPs with various coating are important for better understanding of the transport and subsequent transformation of AgNPs in aquatic environment.

Nanomaterials in the environment: Behavior, fate, bioavailability, and effects—An updated review

“…Some, but not all, of these coatings are known to have associated biological activity. Natural organic matter (NOM; particularly humic substances) has been shown to perform a similar function, with a range of NMs affecting both fate and biological effects (Yin et al ), although often with concomitant effects on the core material (Merrifield et al ). The use of coatings on carbon‐based materials is rarer, with changing properties commonly achieved via surface functionalization (Balasubramanian and Burghard ).…”

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

“…3B). The excellent capability of Ca 2+ in suppressing the interference of humic acid can be attributed to the cation bridging between carboxyl groups on humic acid structures, 40,41 which enhanced the aggregation of humic acid, and therefore reduced the coating of humic acid on the AgCNPs and IOMPs.…”

Effect of sulfidation and dissolved organic matters on toxicity of silver nanoparticles in sediment dwelling organism, Chironomus riparius

“…As DOM is a dispersant, AgNPs are presented in highly dispersed form in AgDM sample (Fig. 1C) (Yin et al, 2015). However, when AgNPs are treated with both DOM and sulfide, the dispersion effect of DOM was abolished (Fig.…”