Cytocompatible Magnetic Nanoparticles with Cell-internalizing Properties for Quantification of the Intracellular Environment

The active control of cellular events is the key technology for progress in cell engineering. In this regard, the quantitative analysis of intracellular reactions and environments is important. Therefore, we designed an external force-responsive device with a cytocompatible surface structure, which consists of Fe3O4-encapsulated polymer nanoparticles covered with phospholipid polymer brush layers. In this paper, we report a method of fabricating Fe3O4-encapsulated core nanoparticles by a soap-free polymerization technique and present a suitable surface modification method to endow the nanoparticles with both cytocompatibility and cell internalization abilities. A delay time of 30 minutes between addition of the ionic monomer and addition of the Fe3O4 nanoparticle suspension is important for the encapsulation of the Fe3O4 nanoparticles into the polystyrene core nanoparticles. The poly(2-methacryoyloxylethyl trimethylammonium chloride (TMAEMA)-block-2-methacryloyloxyethyl phosphorylcholine (MPC)) (PTbM) brush layers on the magnetic core nanoparticles, fabricated by surface-initiated atom transfer radical polymerization, conferred cytocompatibility and cell internalization properties. The magnetic nanoparticles with PTbM chains showed cellular uptake but did not influence cell proliferation.