Challenges and Opportunities for Commercialization of Subplasmonic Silver Nanoclusters

R.I. MacCuspie
Natural Immunogenics,
United States

Keywords: silver nanoparticles, colloidal silver, silver hydrosol

Summary:

Silver has attracted significant commercial interest for its broad spectrum antimicrobial properties. Plasmonic silver nanoparticles have been widely studied in this application space. Subplasmonic silver nanoclusters have particle diameters less than 5 nanometers, providing two key points of differentiation: 1) an increased surface area for converting silver metal into antimicrobial silver ions, and 2) a colorless material property. This talk will focus on both existing and future commercialization of subplasmonic silver nanoclusters. Existing commercialized products include dietary supplements in the colloquially defined colloidal silver category, where significant FDA Dietary Supplement Health and Education Act (DSHEA) and cGMP regulatory challenges exist alongside sizeable market growth opportunity, highlighted by nearly 20 years of growth of silver hydrosol dietary supplements formulated to contain both silver ions and subplasmonic silver nanoclusters. Future opportunities and challenges for commercialization of subplasmonic silver nanoclusters will be surveyed, including applications such as providing safe drinking water, formulation into preservatives, colorless antimicrobial coatings for biodefensive applications, as well as biomedical applications. Technical opportunities exist for subplasmonic silver nanoclusters through demonstration of the antimicrobial efficacy with contact times as short as a few minutes, as well as demonstrated highly uniform particle size distributions at manufacturing scale under GMP conditions with excellent batch to batch consistency. Regulatory challenges are present, however pathways now exist under Federal Insecticide Fungicide and Rodenticide Act (FIFRA), with the Environmental Protection Agency (EPA) Office of Pesticide Programs (OPP) having two products submitted through this pathway, and issuing recalls of products attempting to bypass the regulatory approval process. Industry collaborations may present opportunities to expedite future regulatory approvals. Opportunities exist to shorten product development research by using method standards developed by the National Institute of Standards and Technology (NIST), for example NIST SP1200-8 “Preparation of silver nanoparticle loaded cotton threads to facilitate measurement development for textile applications,” NIST SP1200-21 “Characterization of nanoparticle suspensions using single particle inductively coupled plasma mass spectrometry” and NIST SP1200-13 “Measurement of silver nanoparticle dissolution in complex biological and environmental matrices using UV/visible absorbance measurements.” The talk will conclude with example opportunity scenarios for how industrial collaborations (with either other industrial partners, or academia) could lead to more rapid commercialization of future products.