Just add water: reproducible singly dispersed silver nanoparticle suspensions on-demand

  • Robert I. MacCuspieEmail author
  • Andrew J. Allen
  • Matthew N. Martin
  • Vincent A. Hackley
Research Paper


Silver nanoparticles (AgNPs) are of interest due to their antimicrobial attributes, which are derived from their inherent redox instability and subsequent release of silver ions. At the same time, this instability is a substantial challenge for achieving stable long-term storage for on-demand use of AgNPs. In this study, we describe and validate a “just add water” approach for achieving suspensions of principally singly dispersed AgNPs. By lyophilizing (freeze drying) the formulated AgNPs into a solid powder, or cake, water is removed thereby eliminating solution-based chemical changes. Storing under inert gas further reduces surface reactions such as oxidation. An example of how to optimize a lyophilization formulation is presented, as well as example formulations for three AgNP core sizes. This “just add water” approach enables ease of use for the researcher desiring on-demand singly dispersed AgNP suspensions from a single master batch. Implementation of this methodology will enable studies to be performed over long periods of time and across different laboratories using particles that are identical chemically and physically and available on-demand. In addition, the approach of freeze drying and on-demand reconstitution by adding water has enabled the development of AgNP reference materials with the required shelf-life stability, one of the principal objectives of this research.


Silver nanoparticles Lyophilization Freeze drying Reference materials Reconstitution Dispersion 



ChemMatCARS Sector 15 is principally supported by the National Science Foundation/Department of Energy under Grant Number NSF/CHE-0822838. Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Supplementary material

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Copyright information

© Springer Science+Business Media Dordrecht (outside the USA) 2013

Authors and Affiliations

  • Robert I. MacCuspie
    • 1
    Email author
  • Andrew J. Allen
    • 1
  • Matthew N. Martin
    • 1
  • Vincent A. Hackley
    • 1
  1. 1.Materials Measurement Science DivisionNational Institute of Standards and TechnologyGaithersburgUSA

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