Synthesis and characterization of fluorinated magnetic core-shell nanoparticles for inhibition of insulin amyloid fibril formation.

Maghemite (gamma-Fe2O3) magnetic nanoparticles of 15.0 +/- 2.1 nm are formed by nucleation followed by controlled growth of maghemite thin films on gelatin-iron oxide nuclei. Uniform magnetic gamma-Fe2O3/poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) (gamma-Fe2O3/PHFBA) core-shell nanoparticles are prepared by emulsion polymerization of the fluorinated monomer 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) in the presence of the maghemite nanoparticles. The kinetics of the insulin fibrillation process in the absence and in the presence of the gamma-Fe2O3/PHFBA core-shell nanoparticles are elucidated. A significant direct slow transition from alpha-helix to beta-sheets during insulin fibril formation is observed in the presence of the gamma-Fe2O3/PHFBA nanoparticles. This is in contradiction to our previous manuscript, which illustrated that the gamma-Fe2O3 core nanoparticles do not affect the kinetics of the formation of the insulin fibrils, and to other previous publications that describe acceleration of the fibrillation process by using various types of nanoparticles. These core-shell nanoparticles may therefore be also useful for the inhibition of conformational changes of other amyloidogenic proteins that lead to neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, mad cow and prion diseases.