Measuring Size and Electrophoretic Mobility of Sub 100 nm Particles by Single Particle Tracking

Abstract

Single particle tracking of diffusing nanoparticles can be used to measure their size distribution. In this project gold nanoparticles and products from disaggregating fibrils both ranging from 30 nm to 100 nm were sideways illuminated by a laser. The emitted Rayleigh scattering from the particles was recorded with camera and used to localise the particles. The same technique was used to measure the electrophoretic mobility of 100 nm particles. It was found that, although it is difficult to find the exact size distribution, general differences between different size distributions can be measured. The measurement of the electrophoretic mobility by single particle tracking using this technique induces electro-osmotic effects that are highly dependent on the electric charge, shape and size of the measurement device itself.