A Ferrofluid with Surface Modified Nanoparticles for Magnetic Hyperthermia and High ROS Production

Abstract

A ferrofluid with 1,2-Benzenediol-coated iron oxide nanoparticles was synthesized and physicochemically analyzed. This colloidal system was prepared following the typical co-precipitation method, and superparamagnetic nanoparticles of 13.5 nm average diameter, 34 emu/g of magnetic saturation, and 285 K of blocking temperature were obtained. Additionally, the zeta potential showed a suitable colloidal stability for cancer therapy assays and the magneto-calorimetric trails determined a high power absorption density. In addition, the oxidative capability of the ferrofluid was corroborated by performing the Fenton reaction with methylene blue (MB) dissolved in water, where the ferrofluid was suitable for producing reactive oxygen species (ROS), and surprisingly a strong degradation of MB was also observed when it was combined with H₂O₂. The intracellular ROS production was qualitatively corroborated using the HT-29 human cell line, by detecting the fluorescent rise induced in 2,7-dichlorofluorescein diacetate. In other experiments, cell metabolic activity was measured, and no toxicity was observed, even with concentrations of up to 4 mg/mL of magnetic nanoparticles (MNPs). When the cells were treated with magnetic hyperthermia, 80% of cells were dead at 43 °C using 3 mg/mL of MNPs and applying a magnetic field of 530 kHz with 20 kA/m amplitude.

Keywords: ROS; colloidal-stability; ferrofluid; hyperthermia; superparamagnetism.

Figure 1

(a) FTIR spectra of uncoated MNPs, catechol and coated MNPs; (b) XRD spectra of both coated and uncoated MNPs.

Figure 2

(a) A typical TEM micrograph (300 kx) of coated MNPs and (b) the corresponding bars plot and Gaussian fit.

Figure 3

(a) Dependence of temperature on the mass loss of the uncoated and coated MNPs, the inset are the derivatives of the mass loss plot, and (b) the zeta potential variation between pH = 4.5 and 10.0.

Figure 4

(a) Hysteresis loops of coated and uncoated MNPs and (b) their ZFC-FC plots.

Figure 5

Dependences of: (a) T vs. t for several values f; (b) P vs. f including a linear fit to experimental data; and (c) P vs. H including a quadratic fit to experimental data.

Figure 5

Dependences of: (a) T vs. t for several values f; (b) P vs. f including a linear fit to experimental data; and (c) P vs. H including a quadratic fit to experimental data.

Figure 6

Bar plot representing the absorbance of the samples MBB, MB H₂O₂, MB H₂O₂ UMNP, MB H₂O₂ CMNP, MB UMNP, and MB CMNP.

Figure 7

A sequence of microscope images of the HT-29 cells using a green light filter and a blue light source of the labeled samples: (a) NC; (b) PC; (c) DCF H₂O₂ UMNP; (d) DCF UMNP.

Figure 8

Microscope images of the HT-29 cells using a green light filter and the blue light source, of the labeled samples: (a) DCF H₂O₂ CMNP and (b) DCF CMNP.

Figure 9

Relative metabolic activity of HT-29 cells (a) at different concentrations of coated MNPs and (b) after 20 min of magnetic field irradiation (using 3 mg/mL of MNPs, f = 530 kHz and H ranging from 12 kA/m to 20 kA/m).

Figure 10

Red-stained HT-29 cells (mixed with 3 mg/mL of MNPs and after 24 h of incubation): (a) without MHT exposure; with MHT at (b) 43 °C, and (c) 48 °C.