Aminated β-cyclodextrin-grafted Fe3O4-loaded gambogic acid magnetic nanoparticles: preparation, characterization, and biological evaluation

Abstract

Based on aminated β-cyclodextrin (6-NH₂-β-CD)-grafted Fe₃O₄ and gambogic acid (GA) clathrate complexes, a nanoparticle delivery system was developed with the aim to achieve low irritation, strong targeting, and high bioavailability of a gambogic acid magnetic nanopreparation. 6-NH₂-β-CD grafted onto Fe₃O₄ MNPs was demonstrated by high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential, and magnetic measurements. The average particle size of the Fe₃O₄@NH₂-β-CD MNPs was 147.4 ± 0.28 nm and the PDI was 0.072 ± 0.013. The encapsulation efficiency, drug loading, zeta potential, and magnetic saturation values of the Fe₃O₄@NH₂-β-CD MNPs were 85.71 ± 3.47%, 4.63 ± 0.04%, -29.3 ± 0.42 mV, and 46.68 emu g^-1, respectively. Compared with free GA, the in vitro release profile of GA from Fe₃O₄@NH₂-β-CD MNPs was characterized by two phases: an initial fast release and a delayed-release phase. The Fe₃O₄@NH₂-β-CD MNPs displayed continuously increased cytotoxicity against HL-60 and HepG2 cell lines in 24 h, whereas the carrier Fe₃O₄@NH₂-β-CD MNPs showed almost no cytotoxicity, indicating that the release of GA from the nanoparticles had a sustained profile and Fe₃O₄@NH₂-β-CD MNPs as a tumor tissue-targeted drug delivery system have great potential. Besides, blood vessel irritation tests suggested that the vascular irritation could be reduced by the use of Fe₃O₄@NH₂-β-CD MNPs encapsulation for GA. The t _1/2 and the AUC of the Fe₃O₄@NH₂-β-CD@GA MNPs were found to be higher than those for the GA solution by approximately 2.71-fold and 2.42-fold in a pharmacokinetic study, respectively. The better biocompatibility and the combined properties of specific targeting and complexation ability with hydrophobic drugs make the Fe₃O₄@NH₂-β-CD MNPs an exciting prospect for the targeted delivery of GA.

Scheme 1. Schematic diagram of the synthesis process of Fe₃O₄@NH₂-β-CD@GA MNPs.

Fig. 1. Characterization of Fe₃O₄@NH₂-β-CD@GA MNPs: (a). FTIR spectra of β-CD (a), 6-NH₂-β-CD (b), Fe₃O₄@NH₂-β-CD MNPs (c) and Fe₃O₄@NH₂-β-CD@GA MNPs (d) and (b). The XRD of Fe₃O₄ MNPs (a), Fe₃O₄@NH₂-β-CD MNPs (b) and Fe₃O₄@NH₂-β-CD@GA MNPs (c).

Fig. 2. The HRTEM image of Fe₃O₄@NH₂-β-CD MNPs (a1, a2, a3) and Fe₃O₄@NH₂-β-CD@GA MNPs (b1, b2, b3).

Fig. 3. The size distribution and zeta potential distribution of Fe₃O₄@NH₂-β-CD MNPs and Fe₃O₄@NH₂-β-CD@GA MNPs (n = 3).

Fig. 4. The saturation magnetization curve of Fe₃O₄ MNPs, Fe₃O₄@NH₂-β-CD MNPs, and Fe₃O₄@NH₂-β-CD@GA MNPs.

Fig. 5. Accumulative release of GA and Fe₃O₄@NH₂-β-CD@GA MNPs over time under different pH conditions (n = 3).

Fig. 6. Effects of GA, Fe₃O₄@NH₂-β-CD MNPs, and Fe₃O₄@NH₂-β-CD@GA MNPs on the cell viability of (a) HL-60; (b) HepG2. Cells in 96-well plates were treated with various concentrations of GA, Fe₃O₄@NH₂-β-CD MNPs, and Fe₃O₄@NH₂-β-CD@GA MNPs for 24 h (mean ± SD, n = 3).*p < 0.05, **p < 0.01 compared with the Fe₃O₄@NH₂-β-CD MNPs, ^#p < 0.05, ^##p < 0.01 compared with the GA.

Fig. 7. Pathological paraffin sections (hematoxylin-eosin stain) from the ears of rabbits (×200 magnification). Control group (a–c), GA group (d–f), Fe₃O₄@NH₂-β-CD@GA MNPs (g–i).

Fig. 8. Mean concentration-time profile of GA and Fe₃O₄@NH₂-β-CD@GA MNPs in plasma following i.v. administration of a single dose of 20 mg kg⁻¹ to rats (mean ± SD, n = 6).