Colloidal Stability of Silver Nanoparticles in Biologically Relevant Conditions
Robert I. MacCuspie
Understanding the colloidal stability of nanoparticles may play a key role in interpretation of toxicological experiments, in determining if single nanoparticles or their aggregates provided the dominant result. This report examines a variety of instrumental techniques for surveying the colloidal stability of aqueous suspension of silver nanoparticles (AgNPs) including atomic force microscopy, dynamic light scattering, and colorimetry. It was found that colorimetry can adequately determine the concentration of single AgNPs remaining in solution if morphological information about the aggregates is not required. The colloidal stability of AgNPs with various surface coatings and in various solvents ranging from cell culture media to different electrolytes of several concentrations, and in different pH conditions are determined. It was found that biocompatible bulky coatings, such as bovine serum albumin or starch, that likely provide steric colloidal stabilization, as opposed to electrostatic stabilization such as with citrate AgNPs, provided better retention of single AgNPs in solution over a variety of conditions for up to 64 hours of observation.