Preparation, Characterization, and Antioxidant Properties of Self-Assembled Nanomicelles of Curcumin-Loaded Amphiphilic Modified Chitosan

Abstract

Curcumin (Cur) is a phytochemical with various beneficial properties, including antioxidant, anti-inflammatory, and anticancer activities. However, its hydrophobicity, poor bioavailability, and stability limit its application in many biological approaches. In this study, a novel amphiphilic chitosan wall material was synthesized. The process was carried out via grafting chitosan with succinic anhydride (SA) as a hydrophilic group and deoxycholic acid (DA) as a hydrophobic group; ¹H-NMR, FTIR, and XRD were employed to characterize the amphiphilic chitosan (CS-SA-DA). Using a low-cost, inorganic solvent-based procedure, CS-SA-DA was self-assembled to load Cur nanomicelles. This amphiphilic polymer formed self-assembled micelles with a core-shell structure and a critical micelle concentration (CMC) of 0.093 mg·mL^-1. Cur-loaded nanomicelles were prepared by self-assembly and characterized by the Nano Particle Size Potential Analyzer and transmission electron microscopy (TEM). The mean particle size of the spherical Cur-loaded micelles was 770 nm. The drug entrapment efficiency and loading capacities were up to 80.80 ± 0.99% and 19.02 ± 0.46%, respectively. The in vitro release profiles of curcumin from micelles showed a constant release of the active drug molecule. Cytotoxicity studies and toxicity tests for zebrafish exhibited the comparable efficacy and safety of this delivery system. Moreover, the results showed that the entrapment of curcumin in micelles improves its stability, antioxidant, and anti-inflammatory activity.

Keywords: amphiphilic chitosan; curcumin; nanomicelles.

Figure 1

(A) Infrared spectra of CS (a), CS—SA (b), and CS—SA—DA (c). (B) Nuclear magnetic resonance hydrogen spectra of CS—SA—DA (a), DA (b), CS—SA (c), SA (d), and CS (e). (C) X-ray diffractograms of CS (a), CS—SA (b), and CS—SA—DA (c).

Figure 2

(A) Critical micelle concentration of ACS. (B) Tindal effect map of ACS Cur. (C) TEM image of ACS Cur (staining with 0.5% phosphotungstic acid; scale bar = 50 nm).

Figure 3

(A) Effects of different curcumin inputs on the encapsulation and loading rates. (B) Effects of different sonication times on encapsulation rate and drug loading rate. (C) In vitro release profiles of free Cur and ACS Cur.

Figure 4

(A) Effect of temperature (70 °C) on ACS Cur. (B) Effect of pH (8.0) on the stability of ACS Cur. (C) Ability of ACS Cur to scavenge DPPH radicals. (D) Ability of ACS Cur to scavenge hydroxyl radicals. Note: ** p < 0.01; significant difference compared with the same concentration of the ACS Cur group.

Figure 5

(A) Hemocompatibility of ACS Cur, free Cur, and ACS. (B) Effect of ACS Cur on the survival rate of zebrafish. (C) Effect of ACS Cur on the heart rate of zebrafish. (D) Effect of ACS Cur on the body length of zebrafish.

Figure 6

(A,B) Effects of ACS Cur, free Cur, and ACS on ROS production in zebrafish embryos induced by LPS. (C,D) Effects of ACS Cur, free Cur, and ACS on NO production in zebrafish embryos induced by LPS. Note: * means a significant difference compared with the positive group (p < 0.05); ** means a significant difference compared with the positive group (p < 0.01), and ## means a significant difference compared with the same concentration of the Cur group (p < 0.01).

Figure 7

Effects of ACS Cur, Cur, and ACS on producing pro-inflammatory factors in LPS-stimulated zebrafish embryos: (A) production of IL-1; (B) production of IL-6; * means a significant difference compared with the positive group (p < 0.05).

Scheme 1

Synthesis route of CS—SA—DA.