Silver nanoparticles (AgNPs) are frequently coated by a variety of polymers, which may affect various intertwined mechanisms of toxicity, including agglomeration and dissolution rate. Here, we measure how citrate, dextran, poly(ethylene glycol) (PEG), dextran, and poly(vinyl pyrillodone) (PVP) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated AgNPs using a recently described method. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for thin PEG coatings, and toxicity and dissolution rate decrease with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Since both the AgNP dissolution rate and hemolysis decrease only moderately with large increases in agglomerate size, AgNPs hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to primarily be in the form of AgCl NPs, which are therefore likely to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses.
Pub Type: Journals
Agglomeration, aggregation, hemolysis, nanosilver, polymer-coated silver nanoparticles, silver colloid, dissolution