“Just Add Water” – “Instant” singly-dispersed suspensions of silver nanoparticles on demand

R.I. MacCuspie
National Institute of Standards and Technology, US

Keywords: silver nanoparticles, freeze drying, lyophilization

Summary:

The rapid pace of development of new nanomaterials and new applications has also attracted much attention from the environmental health and safety (EHS) risk assessment community. Subsequently, calls for well-characterized common test materials from a single batch for use in nanoEHS biological and ecological toxicity studies continue to be made to facilitate the intercomparison of these results. However, solution-based decomposition of silver nanoparticles (AgNPs) prevents using a single batch over months or years of study. To overcome this, lyophilization of AgNPs has been demonstrated to recover reproducible singly-dispersed AgNP suspensions. This presentation will show how formulation of the initial suspension of lyophilized AgNPs is critical to recovering singly-dispersed suspensions. Additionally, a “Just Add Water” redispersion protocol that requires only adding deionized water and shaking by hand will be shown to effectively reconstitute the lyophilized powders of AgNPs. Lyophilization of AgNPs under inert atmosphere will enable assessment of whether long-term stability can be increased over solution-based storage approaches. Additionally, this lyophilization approach will be used by the National Institute of Standards and Technology for the development of upcoming silver nanoparticle reference materials.