Hybrid nanoparticles with CO₂-responsive shells and fluorescence-labelled magnetic cores

CO₂-responsive polymer poly(N,N-diethylaminoethylmethacrylate)-modified magnetic nanoparticles (Fe₃O₄@dye/SiO₂-PDEAEMA) were synthesized by atom transfer radical polymerization from the surfaces of silica coated, dye-labelled iron oxide nanoparticles (Fe₃O₄@dye/SiO₂). TEM, FT-IR, and TGA confirmed and quantified the grafted polymer brushes. The prepared magnetic nanoparticles (MNPs) were fluorescence labelled, as shown by the fluorescence spectra and fluorescence microscopy images. This indicated that the nanoparticles could be utilized as imaging probes to monitor the movement of biological cells or other systems. The PDEAEMA polymer brushes on the surface of MNPs endowed them with a protein adsorption ability. The polymer was also CO₂-responsive, so it was a CO₂-triggered reversible protein adsorption/release material, which was demonstrated by the bovine serum albumin (BSA) adsorption experiments. The results indicated that the reversible adsorption/release of protein by bubbling CO₂ and N₂ alternately was easy to achieve.