Internalisation of core-shell superparamagnetic nanoparticles into human granulocytes

In this paper, multitasking core-shell Fe3O4@Cu@Au superparamagnetic nanoparticles (MNPs) functionalised either with folic acid (FA) or methotrexate (MTX) have been used for engulfment of human granulocytes. MNPs internalisation into phagocytes allows to use the cells as carriers thus avoiding the rapid clearance and decreasing of concentration commonly experienced in case of in vivo nanoparticles administration. MNPs have been coated with poly-L-lysine (PLL), which contributes to improve their dispersion into polar solvents. Moreover, this coating improves the cellular uptake and allows the further functionalisation with MTX and FA. Experimental evidences of granulocytes engulfment have been obtained by both SEM and fluorescence microscopy, upon prior labelling of the lysines residues with suitable fluorescent probes. The superparamagnetic nature of the MNPs makes the system easily drivable into a specific tissue upon exposure to a defined magnetic field. The success of the internalisation experiments indicates that the system is a promising tool as theranostic agent for treatment of a variety of diseases, including tumours.