Development of anti-EGFR targeted magnetic nanoparticles for doxorubicin delivery into triple negative breast cancer cells

A new generation of pH-responsive magnetic theranostic nanovectors (NV) has been developed to deliver doxorubicin (DOX) to triple negative breast cancer (TNBC) cells which overexpress epidermal growth factor receptor (EGFR). DOX was loaded onto functionalized NV using a pH-sensitive DOX-Fe²⁺ complex (hereafter called NV_scFv-DOX). NV_scFv-DOX consist of superparamagnetic iron oxide nanoparticles (SPIONs), labelled with Dylight^TM 680 fluorophore, and coated with a layer of covalently bound polyethylene-glycol (PEG) which is partially functionalized with anti-EGFR scFvs (average ratio is ≈12 scFvs per nanovector). The physico-chemical characteristics of the new nanovectors were suitable for IV injection: hydrodynamic diameter D_H below 150 nm, polydispersity index below 0.3 and slightly negative surface charge (≈ -10 mV). Thanks to the functional grafted scFvs, the NV_scFv-DOX were able to recognize the EGFR antigen efficiently. Using preformed DOX-Fe²⁺ complex which binds to the SPION surface in a pH-dependent manner, about 6.5% w/w (DOX/iron oxide) of the drug was loaded onto the NV_scFv-DOX. The drug loading and release in its native form at acidic pH were characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The dual fluorescent response of both Dylight^TM680 and that of DOX was confirmed, which is promising for theranostic use of the nanovectors. Finally, the in vitro toxicity of NV_scFv-DOX on the EGFR-overexpressing TNBC cell line MDA-MB-468 was confirmed and compared to that of free DOX and NV_scFv without DOX. Together, all these properties of the NV_scFv-DOX are promising for their potential use as theranostic platform for TNBC treatment.