Absolute Analysis of Nanoparticle Suspension with Surface Plasmon Microscopy

The recently developed surface plasmon microscopy of single nanoparticles offers a powerful tool for monitoring particle transfer from bulk solution to the adsorbing surface. In the present work, the possibility of absolute analysis of suspension, based on particle transfer observation, was examined. A model based on particle diffusion in a laminar flow, which allows analytical solution of mass transport equation, was considered. It was demonstrated that direct determination of particle concentration, based on counting the particles that bind to the sensor surface, is possible. The model contains only independent, easily to be determined parameters: flow cell geometry, flow rate, particle size and liquid viscosity. For applicability of the model particles should be irreversibly bound when touching the sensor surface. It was demonstrated that the required "perfect binding" is provided in certain electrolyte concentration range, since even particles oppositely charged to the surface do not bind in pure wate...