Surface-initiated atom transfer radical polymerization of cationic corona on iron oxide nanoparticles for magnetic sorting of macrophages

Abstract

Ovalbumin-incorporated antigen carriers were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of iron oxide nanoparticles for magnetic sorting of antigen-presenting cells. Iron oxide nanoparticles were surface-decorated with cationic shells by SI-ATRP, and the primary amines on the surface were further tri-methylated. Surface decoration of the nanoparticles was characterized by Fourier transform infrared spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and transmission electron microscopy with energy-dispersive spectrometry. Ovalbumin-loaded nanoparticles showed higher incorporation in comparison to non-decorated nanoparticles, and the loaded ovalbumin was released faster at low pH than at neutral pH. Ovalbumin-loaded nanoparticles were endocytosed by macrophages, and macrophages with nanoparticles were easily harvested by magnetic separation. Magnetically sorted macrophages showed higher release of cytokines including TNF-α, MIP-1α, and IL-1β than unsorted macrophages. These results suggest that ovalbumin-loaded nanoparticles can potentially increase the efficiency of immune therapy during the antigen-presenting pathway.