Visualization of in vitro protein-rejecting properties of PEGylated stealth® polycyanoacrylate nanoparticles

The in vitro protein-rejecting properties of PEG-coated polyalkylcyanoacrylate (PACA) nanoparticles were for the first time visualized after freeze-fracture of the nanoparticles pre-incubated with fibrinogen as a model blood protein. The reduced protein association to the nanoparticles was evidenced also by two-dimensional PAGE after incubation of the nanoparticles with human plasma. In vivo experiments showed the ‘stealth’ long-circulating properties of the PEGylated nanoparticles after intravenous administration to mice. Thus, the images obtained after nanoparticle–protein incubation were predictive of the behavior observed in vivo. In conclusion, freeze-fracture analysis represents a novel and original qualitative approach to investigate the interactions between proteins and particulate systems.