Hollow-fiber flow field-flow fractionation and multi-angle lightscattering investigation of the size, shape and metal-release of silvernanoparticles in aqueous medium for nano-risk assessment

Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer productsand nanomedicine reliable measurements of properties such as the size, shape and distribution of thesenano particles in aqueous medium is critical. These properties indeed affect both functional propertiesand biological impacts especially in quantifying associated risks and identifying suitable risk-mediationstrategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow fieldflow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) isinvestigated here for this purpose. Data obtained from such a fractionation technique and its combinationthereof with MALS have been compared with those from more conventional but often complementarytechniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spec-troscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scatteringtechniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separationand characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation tech-niques can be conveniently correlated to the mean average diameters determined by multi angle lightscattering and reliable information on particle morphology in aqueous dispersion has been obtained.The ability to separate silver (Ag+) ions from silver nanoparticles (AgNPs) via membrane filtration duringsize analysis is an added advantage in obtaining quantitative insights to its risk potential. Most impor-tantly, the methodology developed in this article can potentially be extended to similar characterizationof metal-based nanoparticles when studying their functional effectiveness and hazard potential.