Formulation and characterization of polyethylenimine-coated magnetopolymeric nanoparticles with potential application in thermal cancer therapies

Abstract

Use of superparamagnetic nanoparticles as heat generators contributed to the development of alternatives to conventional cancer therapies. These nanoparticle-based photothermal and/or magnetothermal therapies can kill malignant cells with negligible effects on surrounding tissues. Maghemite nuclei embedded into a poly(ε-caprolactone) nanomatrix were formulated by interfacial polymer disposition, and the resulting nanostructure was coated with polyethylenimine. DLS, TEM, EDX spectroscopy, electrophoretic and FTIR analysis were used to characterize the resulting ≈ 220 nm-sized (core/shell)/shell particles (PdI ≈ 0.24; ζ ≈ +24 mV). First magnetization curve and microscopic visual analysis defined an adequate magnetic responsiveness. Colloidal stability of two years was demonstrated at room temperature and at refrigeration conditions, measuring size, zeta potential and pH of the colloid; and, by evaluation of nanoparticle interactions with bovine serum albumin. Biocompatibility was postulated from hemocompatibility assays and cytotoxicity studies in CCD-18 fibroblasts and T-84 cancer cells. Hyperthermia characterizations revealed the capacity of the polyethylenimine-coated (maghemite/poly(ε-caprolactone)) particles to generate heat in an effective and field frequency-dependent manner. Temperature increases up to ≈ 45 °C (SAR ≈ 265 W/g, ILP ≈ 7 nH·m2·Kg−1) under a magnetic field intensity and frequency of 17 kA/m and 120 kHz, respectively. Local heating was also observed in photothermal assays: temperature increases proportional to laser power, reaching ≈ 43 °C when the aqueous dispersion of nanoparticles was kept under a near-infrared laser with a wavelength of 850 nm and a power density of 2 W/cm2. These polyethylenimine-coated magnetopolymeric nanoparticles may find promising applications for hyperthermia and photothermal cancer therapy.