Fe3O4-PAA–(HP-γ-CDs) Biocompatible Ferrimagnetic Nanoparticles for Increasing the Efficacy in Superparamagnetic Hyperthermia

Abstract

In this paper, we present the obtaining of Fe3O4-PAA–(HP-γ-CDs) ferrimagnetic nanobioconjugates (PAA: polyacrylic acid, HP-γ-CDs: hydroxypropyl gamma-cyclodextrins) in a hybrid core-shell biostructure (core: inorganic Fe3O4 nanoparticles, and shell: organic PAA–(HP-γ-CDs)) and their use in superparamagnetic hyperthermia without cellular toxicity and with increased efficacy for future alternative cancer therapy. In order to design the optimal experimental conditions for obtaining nanobioconjugates and then superparamagnetic hyperthermia (SPMHT), we used molecular docking simulation and computational assessment of the maximum specific loss power (SLP) that led to nanoparticles’ heating. The nanoparticles and nanobioconjugates obtained were studied and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed-infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and magnetic measurements (MMs). The cell viability of the nanoparticles and nanobioconjugates was assessed by means of the MTT assay using human immortalized keratinocytes (HaCaT) as an in vitro model. Superparamagnetic hyperthermia with nanoparticles and nanobioconjugates was obtained experimentally in a magnetic field of 15.92 kA/m and frequency of 312.2 kHz for the magnetic nanoparticle core with a (average) diameter of 15.8 nm, which resulted in the maximum hyperthermic effect that led to a temperature of ~42.5 °C necessary in the therapy of tumors in a short time so as not to affect healthy tissues. The biological screening of Fe3O4-PAA nanoparticles and PAA–(HP-γ-CDs) nanobioconjugates showed no cytotoxic effect on HaCaT cells for a time interval of 24 h, both under standard (37 °C) and hyperthermia conditions (42.5 °C). Thus, Fe3O4-PA–(HP-γ-CDs) ferrimagnetic nanobioconjugates can be used successfully in superparamagnetic hyperthermia without toxicity and with increased efficiency due to the small layer thickness of the PAA–(HP-γ-CDs) shell, which is suitable in this alternative therapeutic technique.

High Efficacy on the Death of Breast Cancer Cells Using SPMHT with Magnetite Cyclodextrins Nanobioconjugates

“…Considering the above aspects, we previously proposed the use of Fe 3 O 4 nanoparticles coated with gamma cyclodextrins (γ-CDs) [17,18] to increase the effectiveness and reduce cellular toxicity to a minimum. We also found the optimal conditions [19] in which superparamagnetic hyperthermia (SPMHT) can be applied for maximum effectiveness on tumors.…”

“…We also found the optimal conditions [19] in which superparamagnetic hyperthermia (SPMHT) can be applied for maximum effectiveness on tumors. These aspects were studied by us both theoretically [17,19] and experimentally [18], and the recent experimental results showed the possible successful application of nanobioconjugates of Fe 3 O 4 -PAA-(HP-γ-CDs) (PAA is polyacrylic acid, HP-γ-CDs is hydroxypropyl gamma cyclodextrin) on the destruction of tumors through SPMHT [18], which is more effective than MHT [20]. We used γ-CDs for the bioconjugation of Fe 3 O 4 magnetic nanoparticles, due to their advantages for magnetic hyperthermia.…”

“…Using the optimal conditions previously established by us [17][18][19] for the efficient implementation of SPMHT, in this study we present the experimental results that we obtained in vitro by applying SPMHT using Fe 3 O 4 -PAA-(HP-γ-CDs) nanobioconjugates on MCF-7 human breast adenocarcinoma cells. We chose this cancer for in vitro testing due to its high incidence in women and high mortality rate, according to the World Health Organization [23].…”

“…(i) The use in superparamagnetic hyperthermia experiments in vitro of biocompatible Fe 3 O 4 -PAA-(HP-γ-CDs) magnetic nanobioconjugates previously obtained by us, which have not been used so far in the superparamagnetic hyperthermia of tumors; (ii) Experimental demonstration of the high efficacy of SPMHT using Fe 3 O 4 -PAA-(HP-γ-CDs) nanobioconjugates via testing in vitro on the MCF-7 breast cancer cell line, with very good results regarding the death of tumor cells at a very high percentage (up to approximately 95%); (iii) Based on our experimental results on MCF-7 cells, we established a new upper biological limit for the magnetic field without cellular damage for which magnetic hyperthermia can be safely applied on MCF-7 cells: we found that the maximum admissible biological limit can be extended to a double value compared to the previously known one, with superior advantages in the practical implementation of SPMHT for tumors to increase its efficacy and reduce cellular toxicity. For in vitro SPMHT on MCF-7 breast tumor cells, we used our previously obtained Fe 3 O 4 -PAA-(HP-γ-CDs) nanobioconjugates [18]. First, ferrimagnetic Fe 3 O 4 nanoparticles were obtained by the chemical co-precipitation method; then, the polyacrylic acid (PAA) adsorbed on their surface [24,25] was used for binding (bioconjugation) with hydroxypropylgamma-cyclodextrins (HP-γ-CDs), in the second stage, following the procedure described in detail in reference [18].…”

“…For in vitro SPMHT on MCF-7 breast tumor cells, we used our previously obtained Fe 3 O 4 -PAA-(HP-γ-CDs) nanobioconjugates [18]. First, ferrimagnetic Fe 3 O 4 nanoparticles were obtained by the chemical co-precipitation method; then, the polyacrylic acid (PAA) adsorbed on their surface [24,25] was used for binding (bioconjugation) with hydroxypropylgamma-cyclodextrins (HP-γ-CDs), in the second stage, following the procedure described in detail in reference [18]. We used the branched cyclodextrins HP-γ-CDs because by the molecular docking method, we previously showed that this nanobiostructure is the most stable.…”