Preparation, Characterization, and In Vitro Release of Curcumin-Loaded IRMOF-10 Nanoparticles and Investigation of Their Pro-Apoptotic Effects on Human Hepatoma HepG2 Cells

Abstract

Curcumin (CUR) has a bright future in the treatment of cancer as a natural active ingredient with great potential. However, curcumin has a low solubility, which limits its clinical application. In this study, IRMOF-10 was created by the direct addition of triethylamine, CUR was loaded into IRMOF-10 using the solvent adsorption method, and the two were characterized using a scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) methods, and Brunauer-Emmett-Teller (BET) analysis. We also used the MTT method, 4',6-diamidino-2-phenylindole (DAPI) staining, the annexin V/PI method, cellular uptake, reactive oxygen species (ROS), and the mitochondrial membrane potential (MMP) to perform a safety analysis and anticancer activity study of IRMOF-10 and CUR@IRMOF-10 on HepG2 cells. Our results showed that CUR@IRMOF-10 had a CUR load of 63.96%, with an obvious slow-release phenomenon. The CUR levels released under different conditions at 60 h were 33.58% (pH 7.4) and 31.86% (pH 5.5). Cell experiments proved that IRMOF-10 was biologically safe and could promote curcumin entering the nucleus, causing a series of reactions, such as an increase in reactive oxygen species and a decrease in the mitochondrial membrane potential, thereby leading to cell apoptosis. In summary, IRMOF-10 is an excellent drug carrier and CUR@IRMOF-10 is an effective anti-liver cancer sustained-release preparation.

Keywords: HepG2 cells; IRMOF-10; MOFs; curcumin.

Figure 1

Chemical structure diagram of curcumin.

Figure 2

Schematic illustration of the construction of IRMOF-10.

Figure 3

Characteristics of IRMOF-10 and CUR@IRMOF-10: (A) SEM image of IRMOF-10; (B) SEM image of CUR@IRMOF-10; (C) X-ray diffraction (XRD) analysis of IRMOF-10.

Figure 4

Particle size distribution of (A) IRMOF-10 and (B) CUR@IRMOF-10; (C) Fourier transform infrared spectrometer (FTIR) spectra of IRMOF-10 and CUR@IRMOF-10; (D) thermogravimetric (TG) analysis of IRMOF-10 and CUR@IRMOF-10.

Figure 5

Brunauer–Emmett–Teller (BET) of IRMOF-10: (A) N₂ adsorption and desorption isotherm of IRMOF-10; (B) pore size distribution of IRMOF-10.

Figure 6

Release characteristics of CUR@IRMOF-10: (A) release curve of CUR@IRMOF-10 under different pH conditions (n = 3); (B) fitting curve of CUR@IRMOF-10 by different mathematical models under different pH values (5.5 and 7.4).

Figure 7

Safety of IRMOF-10: (A) MTT method to determine the safe concentration range of IRMOF-10 for HepG2 cells; (B) fluorescence micrographs of HepG2 cells stained with DAPI after 24 h of treatment with three concentrations of IRMOF-10.

Figure 8

Safety of IRMOF-10: (A) proportion of viable, necrotic, and apoptotic HepG2 cells after incubation with different concentrations of IRMOF-10 for 24 h; (B) flow cytometry detection of apoptosis with FITC-annexin V/PI double staining.

Figure 9

Toxicity of CUR and CUR@IRMOF-10 for HepG2 cells: (A) cell survival rate of HepG2 cells incubated with different concentrations of CUR and CUR@IRMOF-10 for 24 and 48 h—* p < 0.05, ** p < 0.01, and *** p < 0.001 vs. control; (B) fluorescence microscopic images of HepG2 cells stained with DAPI after 24 h treatment with CUR or CUR@IRMOF-10 (at IC₅₀ value).

Figure 10

Statistical analysis of viable, necrotic, and apoptotic HepG2 cells with CUR (A) or CUR@IRMOF-10 (B)—**** p < 0.0001 vs. control. Apoptosis assays for HepG2 cells after treatment with CUR (C) or CUR@IRMOF-10 (D).

Figure 11

Cell uptake and ROS content determination: (A) confocal microscopy images of HepG2 cells after incubation with CUR for 30 min; (B) effect of CUR or CUR@IRMOF-10 on endogenous reactive oxygen species (ROS) level in HepG2 cells (administered concentration calculated based on IC₅₀ of CUR).

Figure 12

Effect of CUR and CUR@IRMOF-10 on the mitochondrial membrane potential of HepG2 cells. Red fluorescence represents the aggregate form of JC-1 (A); green fluorescence represents the monomeric form of JC-1 (B) (administered concentration calculated based on IC₅₀ of CUR).