Polymeric nanocapsules ultra stable in complex biological media

Non-specific protein adsorption from complex biological media, especially from blood plasma, is an urgent challenge for the application of nanoparticles as delivery systems, diagnostics, and other biomedical application. Nanocapsules (NC) prepared from FDA-approved degradable poly(ɛ-caprolactone) shell and Mygliol 812(®) oil in the core were coated with mono-methoxy terminated oligo(ethylene glycol) methacrylate (poly(MeOEGMA)) polymer brush layers with a well-controlled thickness at the nanometer scale up to 350 nm using surface initiated atom transfer radical polymerization in water or phosphate buffered saline. Incubation of uncoated NC with human serum albumin solution, fetal bovine serum, or human blood plasma resulted in fast aggregation observed by dynamic light scattering as an increase in diameter of particles present in the solutions. Conversely, these biological fluids affected only marginally the size distribution of the NC coated with a 60 nm thick poly(MeOEGMA) layer. The high suspension stability of the coated NC in complex biological fluids was related to the suppressed deposition of proteins from these fluids observed by surface plasmon resonance (SPR) on analogous poly(MeOEGMA) layer prepared on flat surfaces of SPR chips.