Hollow carbon nanospheres embedded with stoichiometric γ-Fe2O3 and GdPO4: tuning the nanospheres for in vitro and in vivo size effect evaluation

A series of hollow carbon nanospheres embedded with MRI agents γ-Fe2O3 and GdPO4 nanoparticles (Fe–Gd/HCS), were prepared and applied to in vitro/vivo evaluation with well defined sizes of ∼100 nm, ∼200 nm, ∼300 nm, respectively.