Magnetic–fluorescent Langmuir–Blodgett films of fluorophore-labeled ferritin nanoparticles

We have covalently coupled fluorophore 4-(2-hydroxyethoxy)-7-nitro-2,1,3-benzoxadiazole (NBD) to the external ferritin shell through lysine residues. An increase in the luminescence quantum yield of the fluorescent ferritin particles and a blue shift in its emission peak compared to individual fluorophore were observed. The study of the particles by transmission electron microscopy showed that the native iron core ferritin is intact and that no degradation occurs during chemical functionalization of the protein shell. The NBD-labeled ferritin particles are water soluble, which allowed their controlled deposition by the Langmuir–Blodgett (LB) technique. Superparamagnetic and fluorescent properties of the particles are preserved within the LB film.

Graphical abstractA fluorophore-labeled ferritin has been prepared by coupling of 7-(2-hydroxyethoxy)-4-nitrobenzofurazan (NBD) to the protein surface lysine residues. The particles are water soluble, which allowed their controlled deposition by the Langmuir–Blodgett (LB) technique. Magnetic measurements and fluorescence spectroscopy showed that the superparamagnetic and fluorescent properties of the particles are preserved within the LB film.Figure optionsDownload full-size imageDownload as PowerPoint slide