In vivo monitoring of rat macrophages labeled with poly( l ‐lysine)‐iron oxide nanoparticles

Coprecipitation of FeCl 2 and FeCl 3 with aqueous ammonia was used to prepare iron oxide nanoparticles dispersible in aqueous medium. Oxidation of the particles with sodium hypochlorite then yielded maghemite (γ‐Fe 2 O 3 ) nanoparticles which were coated with two types of coating – d ‐mannose or poly( l ‐lysine) (PLL) as confirmed by FTIR analysis. The particles were <10 nm according to transmission electron microscopy. Their hydrodynamic particle size was ∼180 nm (by dynamic light scattering). The d ‐mannose‐, PLL‐coated, and neat γ‐Fe 2 O 3 particles as well as commercial Resovist® were used to label rat macrophages. The viability and contrast properties of labeled macrophages were compared. PLL‐coated γ‐Fe 2 O 3 nanoparticles were found optimal. The labeled macrophages were injected to rats monitored in vivo by magnetic resonance imaging up to 48 h. Transport of macrophages labeled with PLL‐γ‐Fe 2 O 3 nanoparticles in rats was confirmed. Tracking of macrophages using the developed particles can be used for monitoring of inflammations and cell migration in cell therapy. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1141–1148, 2015.