Development of a Self-Assembled Hydrogels Based on Carboxymethyl Chitosan and Oxidized Hyaluronic Acid Containing Tanshinone Extract Nanocrystals for Enhanced Dissolution and Acne Treatment

Abstract

This study aimed to construct a pH-responsive nanocrystalline hydrogel drug delivery system for topical delivery of insoluble drugs based on the self-assembly behavior of carboxymethyl chitosan (CMC) and oxidized hyaluronic acid (OHA). The tanshinone nanocrystal (TNCs) extract was prepared by dielectric milling method, the type and ratio of stabilizer of the drug were investigated to optimize the prescription, and the effector surface method was used to optimize the preparation process. OHA was prepared by the sodium periodate oxidation method, and the concentration of CMC and OHA was optimized using gel formation time as an indicator. OHA was dissolved in TNCs and self-assembled with CMC solution to form tanshinone extract nanocrystal hydrogels (CMC-OHA/TNCs), of which the physicochemical properties and in vitro antibacterial activity were evaluated. Results showed that the optimized prescription and process could produce tanshinone extract nanocrystals with a particle size of (223.67 ± 4.03) nm and a polydispersity index (PDI) of 0.2173 ± 0.0008. According to SEM and XRD results, TNCs were completely wrapped in the hydrogel as nanoparticles, and the crystallinity of TNCs was reduced and the diffraction peaks in CMC-OHA/TNCs almost disappeared. In vitro, transdermal test results showed that CMC-OHA/TNCs could release the drug continuously at the acne lesions. The cell-counting kit-8 (CCK-8) assay confirmed that the CMC-OHA/TNCs had no obvious cytotoxicity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CMC-OHA/TNCs against Propionibacterium acnes and Staphylococcus aureus were significantly lower and the diameter of the inhibition circle was obviously higher than that of TNCs and tanshinone extract crude suspension. This study demonstrated that CMC-OHA/TNCs was a promising delivery system for topical delivery of insoluble drugs, which could improve the solubility of tanshinone extract and enhance its in vitro bacterial inhibitory activity.

Keywords: acne; hydrogels; nanocrystals; poorly water-soluble drug; self-assembled.

Figure 1

The effects of different stabilizers on the particle size and PDI of TNCs.

Figure 2

The effects of different ratios of P407 to TE on particle size and PDI values of TNCs.

Figure 3

Three-dimensional contour plot showing the effect of independent variables on response of particle size and PDI of TNCs. (A) X1 and X2 on response Y1, (B) X1 and X3 on response Y1, (C) X2 and X3 on response Y1, (D) X1 and X2 on response Y2, (E) X1 and X3 on response Y2, (F) X2 and X3 on response Y2. , design points above predicted value; ○, design points below predicted value.

Figure 4

FT-IR spectra of HA and OHA.

Figure 5

Gelation time of the hydrogels formed with different concentrations of CMC and OHA.

Figure 6

Appearance of CMC-OHA/TNCs.

Figure 7

SEM photographs of TE powders (A), TNCs (B) CMC-OHA hydrogels (C) and CMC-OHA/TNCs (D).

Figure 8

XRD for TE (A), TNCs (B), OHA and CMC powders (C) and CMC-OHA/TNCs (D).

Figure 9

In vitro transdermal of tanshinone IIA (A) and cryptotanshinone (B) at different pH receptive solutions (pH = 5.0, 5.5, and 7.4).

Figure 10

Cell viability of 3T3-L1 following incubation with CMC-OHA/TNCs for 48 h. ns = non-significant.

Figure 11

Antibacterial activity of CMC-OHA/TNCs in vitro.

Figure 12

Schematic representation of the formation of CMC-OHA/TNCs.