Authors: D. Griffiths, P. Hole, J. Smith, A. Malloy, B. Carr
Affilation: NanoSight, United States
Pages: 37 - 40
Keywords: nanoparticle, size, fluorescence, light scattering
A novel addition to a technique for the analysis of nanoparticles in a suspension is described. The Nanoparticle Tracking Analysis (NTA) technique sizes individual nanoparticles, based on their Brownian motion. Unlike classical light scattering techniques, NTA allows nanoparticles to be sized on a particle-by-particle basis. This results in a higher resolution and therefore a better understanding of polydispersity than ensemble methods (such as dynamic light scattering, DLS) and it also yields directly a count/concentration measurement. Analysis of scattering intensity is a recent development allowing sub-populations of nanoparticles with varying scattering characteristics to be resolved in a complex mixture. Now this technique has been extended to the analysis and differentiation of fluorescently labeled nanoparticles. With the appropriate wavelength lasers and optical filters, the technique has been shown to be able to differentiate between sub-populations in a heterogeneous mixture. Tests on fluorescently labeled and non-fluorescent standards have been performed to demonstrate proof of principle of the technique to quantitatively count proportions of labeled particles and differentiate between labeled and unlabelled particles. Real life biological samples have also been used to demonstrate the ability to identify populations of labeled and unlabeled nanoparticles within a suspension.