Water-dispersible polyphosphate-grafted Fe3O4 nanomagnets for cancer therapy

Abstract

We report the development of a new class of water-dispersible polyphosphate-grafted Fe₃O₄ nanomagnets (PPNMs) by a facile soft chemical approach. The grafting of polyphosphate with Fe₃O₄ nanoparticles is evident from Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS) and zeta-potential measurements. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses reveal the formation of highly crystalline Fe₃O₄ nanoparticles with an average size of about 10 nm. These nanoparticles show good colloidal stability, strong magnetic field responsivity and protein resistance characteristics. Induction heating studies confirm localized heating of these superparamagnetic PPNMs with good intrinsic loss power under an AC magnetic field (AMF). The drug loading and release behavior of the PPNMs was explored using doxorubicin hydrochloride (DOX) as a model drug. The decrease in fluorescence intensity and increase in surface charge of drug-loaded PPNMs strongly suggest the conjugation of DOX with the PPNMs. The cell viability and hemolysis assays suggest that the PPNMs do not have adverse toxic effects for further in vivo use. Specifically, high loading affinity for DOX with sustained release, substantial cellular internalization and self-heating capacity makes these novel magnetic nanoparticles suitable for drug delivery and hyperthermia therapy applications.