A TA/Cu2+ Nanoparticle Enhanced Carboxymethyl Chitosan-Based Hydrogel Dressing with Antioxidant Properties and Promoting Wound Healing

Abstract

Background: As the first line of immune defense and the largest organ of body, skin is vulnerable to damage caused by surgery, burns, collisions and other factors. Wound healing in the skin is a long and complex physiological process that is influenced by a number of different factors. Proper wound care can greatly improve the speed of wound healing and reduce the generation of scars. However, traditional wound dressings (bandages, gauze, etc.) often used in clinical practice have a single function, lack of active ingredients and are limited in use. Hydrogels with three-dimensional network structure are a potential biomedical material because of their physical and chemical environment similar to extracellular matrix. In particular, hydrogel dressings with low price, good biocompatibility, degradability, antibacterial and angiogenic activity are favored by the public.

Methods: Here, a carboxymethyl chitosan-based hydrogel dressing (CMCS-TA/Cu²⁺) reinforced by copper ion crosslinked tannic acid (TA/Cu²⁺) nanoparticles was developed. This study investigated the physical and chemical characteristics, cytotoxicity, and angiogenesis of TA/Cu²⁺ nanoparticles and CMCS-TA/Cu²⁺ hydrogels. Furthermore, a full-thickness skin defect wound model was employed to assess the in vivo wound healing capacity of hydrogel dressings.

Results: The introduction of TA/Cu²⁺ nanoparticles not only could increase the mechanical properties of the hydrogel but also continuously releases copper ions to promote cell migration (the cell migration could reach 92% at 48 h) and tubule formation, remove free radicals and promote wound healing (repair rate could reach 90% at 9 days).

Conclusion: Experiments have proved that CMCS-TA/Cu²⁺ hydrogel has good cytocompatibility, antioxidant and wound healing ability, providing an advantageous solution for skin repair.

Keywords: TA/Cu2+ nanoparticles; antioxidant activity; carboxymethyl chitosan; wound dressing.

Graphical abstract

Figure 1

Preparation process diagram of the CMCS-TA/Cu²⁺ hydrogel (The red text mark indicates the formation of a coordination bond between Cu²⁺ and TA in the TA/Cu²⁺ nanoparticle).

Figure 2

(A) TEM images of TA/Cu²⁺nanoparticles, (B) Particle size distribution of TA/Cu²⁺ hydrogels. (C) FTIR spectra of TA and TA/Cu²⁺ hydrogels. (D) XRD profiles of various hydrogels.

Figure 3

(A) Swelling rate. (B) Porosity and (C) SEM images of various hydrogels. A one-way ANOVA was used to determine statistical significance: *p < 0.05, **p < 0.01.

Figure 4

(A) UV-vis spectra of different components. (B) DPPH quenching efficiency. (C) Release rate of Cu²⁺ from CMCS-TA/Cu²⁺ hydrogels for 14 days in vitro. A one-way ANOVA was used to determine statistical significance: *p < 0.05, **p < 0.01.

Figure 5

Results of in vitro cytocompatibility testing. (A) CCK-8 assay and (B) cell viability on hydrogels after 1, 3 and 5 days of culture. (C) Images of live/dead staining of cells following incubation on hydrogels. (D) Images taken using a confocal laser scanning microscope (CLSM) show HUVECs stained with rhodamine-coupled phalloidin (red) and DAPI (blue) after three days of growth. A one-way ANOVA was used to determine statistical significance: *p < 0.05, **p < 0.01.

Figure 6

(A) Photographs of HUVECs migration. (B) Images of HUVECs tube formation in vitro. (C) Migration rate of HUVECs. (D) Statistical results of HUVECs tubes formation in co-culture with various hydrogels. A one-way ANOVA was used to determine statistical significance: *p < 0.05, ***p < 0.001.

Figure 7

(A) Rat wound model. (B) Images showing the state of the wound at various times. (C) Wound healing rate. (D) H&E and (E) Masson staining on day 7 and 14 for various groups.