(464f) Influence of the Surface Charge on the Brownian Motion of Colloidal Particles Near Surfaces with Biomimetic Characteristics

Many important biological phenomena, such as bacterial invasion, absorption of food particles or cleansing of impurities are set up at the interface between biological fluids and tissues. Such processes commence with non-specific interactions between surfaces (mucosa, epithelia, endothelia) and colloids (mucus, bacteria, dirt particles), when the colloids are in the vicinity of the surfaces. Knowledge of these phenomena is relevant for the engineering of drug delivery systems or the modification of the adhesion properties of tissues and biomaterials.

In this work, we used fluorescent colloidal particles suspended in proximity of surfaces functionalized with biomolecules. The colloidal particles were tracked three-dimensionally by digital video microscopy. From their trajectories we computed their mean square displacement to calculate the diffusion coefficient in directions parallel and perpendicular to the surface. We used both negatively-charged and positively-charged colloidal micro-particles on surfaces functionalized with poly-L-lysine, hyaluronic acid and phospholipid monolayers and found differences in the parallel and the perpendicular diffusions highly dependent on the interfacial characteristics of the colloidal particles and the surfaces.