Development of a Single Particle Tracking Microscope for the Study of Nanoparticle Diffusion

Transport of nanoparticles, including proteins in stationary phases used for chromatography is controlled by diffusion. Our understanding of diffusion in such systems is based almost exclusively on macroscopic and microscopic scale measurements. Our knowledge is especially limited when transport is coupled to interactions with the matrix. Macroscopic and microscopic-scale measurements provide ensemble-averaged information, but offer little detail on the movement of individual nanoparticles. Therefore, a nanoscopic-scale measurement about the transport of individual nanoparticles is desirable. In this thesis, a single particle tracking microscope was developed to determine the movement of individual nanoparticles in solution. The tracking microscope used a total internal reflection fluorescence microscope with laser light illumination to measure the movement of individual fluorescent nanoparticles through water and glycerol solutions. Observations of Brownian motion were used to determine experimental diffusion coefficients, which were compared to diffusion coefficients calculated with the theoretical Stokes-Einstein equation. The experimental diffusion coefficients were comparable to the theoretical values, and therefore, support the use of the tracking microscope for the measurement the diffusion of molecules both in solution and polymer gel matrices used for chromatography.