(179n) Polystyrene Nanoparticle Interactions with Albumin: Changes in Particle Characteristics and Interparticle Forces

The biological activity of nanoparticles for pulmonary drug delivery applications is dependent on their interactions with lung proteins. Such interactions can change nanoparticle physicochemical properties and ultimately affect their in-vivo fate. However, studies of such interactions are complicated due to the wide range of proteins in the lungs and potential competition behavior in protein adsorption onto nanoparticle surfaces. Thus, mechanistic information from simpler systems is needed before a more complex system with multiple proteins can be tackled. The current study focuses on interactions of albumin, the most common protein in the conducting airways with negatively charged carboxyl modified polystyrene nanoparticles (200 nm).

Nanoparticle interactions with proteins were studied by monitoring size and charge of nanoparticles in suspension after incubation with albumin for different time periods. A significant reduction in particle charge along with a slight increase in particle size was observed after incubation. The changes in particle properties were time dependent with the maximum size and minimum charge occurring at the longest interaction time (2 hours). The DLVO model was used to predict the interparticle forces between nanoparticles in suspension. The model was modified to predict the forces after adsorption of one layer of albumin on nanoparticle surfaces. Based on the model estimations, a significant drop in aggregation energy barrier will occur once the nanoparticles are completely covered with a layer of albumin. These results suggest that nanoparticle surfaces are partially covered by albumin upon incubation.