In the regeneration process for new tissues, oxygen promotes re-epithelialization and healing of infected wounds, increases keratinocyte differentiation, proliferation and migration of fibroblast, and induces angiogenesis, collagen synthesis and wound contraction. Therefore, provision of oxygen to cells and tissues at an optimal level is critical for effective tissue regeneration and wound healing. In this study, we developed sustained oxygen-releasing polymeric microspheres and fabricated a sponge type dressing by embedding the microspheres into alginate-based hydrogel that can supply oxygen to wounds. We further investigated the applicability of the microspheres and hydrogel sponge to wound healing in vitro and in vivo. Oxygen-releasing microspheres (ORM) were made by incorporating hydrogen peroxide (H₂O₂) into poly(lactic-co-glycolic acid) (PLGA) using double emulsion method. H₂O₂-PLGA microspheres were embedded into alginate-based hydrogel to form a porous oxygen-releasing hydrogel sponge (ORHS). Biocompatibility was performed using cell counting kit-8. The oxygen release kinetic study was performed using a hydrogen peroxide assay kit and oxygen meter. The wound healing potential of ORHS was evaluated using the wound scratch model. In vivo studies were carried out to investigate the safety and efficacy of the ORHS for wound healing. Experimental results confirmed that oxygen released from ORMand ORHS induced neovascularization and promoted cell proliferation thereby facilitating effective wound healing. It is suggested that the ORM can be used for supplying oxygen to where cells and tissues are deprived of necessary oxygen, and ORHS is an intelligent scaffold to effectively heal wound by enhanced angiogenesis by oxygen. Conclusively, oxygen releasing polymeric microspheres and hydrogel scaffolds have potential for a variety of tissue engineering applications, where require oxygen.

Immediate burn wound care is a critical factor influencing the outcomes of burn treatment. In this study, we developed a spray-type alginate hydrogel dressing that promotes wound healing, reduces pain, and increases the convenience of use in a burn treatment emergency. We investigated the efficiency of newly developed spray-type alginate hydrogel dressing on the wound healing process. We investigated the efficacy of the alginate hydrogel dressing for wound healing in 30 Sprague Dawley rats. Four deep, round second-degree burn wounds (diameter, 1.5 cm) were created bilaterally on the dorsum of the rat’s trunk; the rats were divided into four groups, in which different dressing materials were applied as follows: group A, gauze (control); group B, Mepilex™ (control); group C, 2.25% alginate hydrogel; and group D, 2.5% alginate hydrogel. The gross findings of each group were compared by tracing the remaining wound and performing visual and histological observations and biochemical analysis for proteins associated with wound healing at each time period. In burn wounds, groups C and D showed significantly higher contraction, epithelialization, and healing rates. Histologically, groups C and D showed an improved arrangement of collagen fibers and a thick epithelial layer 14 days after initial wound formation. Group C showed higher CD31, TGF-β, and fibronectin expression in Western blot analyses after day 14. This study suggests that the spray-type alginate hydrogel dressing is an effective material for initial burn wound care.

This study focused on the manufacturing of functional superabsorbent sponges using natural polymers. An alginate/CMC-embedded dextran hybrid dual-layer formulation was prepared using the freeze-drying method. The physical properties of the formulation were characterized using a field emission scanning electron microscope and a universal testing machine, and the swelling ratio was calculated. Cell viability assays were performed using keratinocytes (HaCaT cells). The results showed that this formulation can absorb a large amount of moisture and provide morphological stability through its tensile strength and uniform porosity, and this was verified by its biocompatibility. We believe that in the future, by combining this novel hybrid dual-layer superabsorbent sponge with antibacterial agents with excellent porosity, it would serve as a medical material for producing bandages that can absorb blood and body fluids, feminine hygiene products, and functional antibacterial masks.

Although there is no cure for atopic dermatitis (AD), treatments to relieve AD symptoms are available. A previously developed topical patch for AD treatment minimizes skin irritation but does not sufficiently adhere and absorb to specific areas. Centella asiatica extract (CAE) is a natural polymer for atopic treatment. This study fabricated a CAE-loaded hyaluronic acid-dextran (HA-Dex) hybrid hydrogel patch for use as an AD treatment and evaluated the effect of varying CAE concentrations in the patch. The CAE-loaded HA-Dex hybrid hydrogel patch was fabricated into a sheet-type scaffold using a freeze-drying process and 1,4-butanediol diglycidyl ether (BDDE). Fibroblasts (L929 cells) were used to evaluate cell survival, and physical properties were evaluated using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, a universal testing machine, and high-performance liquid chromatography. A 0.4 wt% CAE-loaded HA-Dex hybrid hydrogel patch produced the most stable release profile and the highest level of cellular activity. These hydrogel patches provided moisture and released CAE over an extended period of time, making them ideal for relieving atopic itching. This delivery system enables the extended release of CAE to localized areas and could potentially be used to apply a variety of products to treat AD.

Sufficient oxygenation for prevention of cellular damage remains a critical barrier to successful tissue engineering, especially in the construction of a large-sized tissue despite numerous attempts to resolve this issue in recent years. There have been a number of hypothetical solutions to this problem, including the use of artificial oxygen carriers, induction of vascularization, and fabrication of oxygen-generating biomaterials. All of these efforts have improved the efficiency of oxygen supply, but none have been able to support the large tissue mass required for clinical application. Necrosis, which often occurs during hypoxic stress, is one of the most significant limitations in large-sized tissue regeneration. In this study, we developed an oxygen producing capsule using hydrogen peroxide (H₂O₂), PLGA (poly (lactic-co-glycolic acid) and alginate, and also evaluated the capsule as a model of a large-sized tissue. Firstly, H₂O₂ was microencapsulated by PLGA, and subsequently the H₂O₂-PLGA microspheres were embedded into a catalase-immobilized alginate capsule of 5.0 mm in diameter. The alginate capsules of a fairly large size were characterized for their oxygenation capability to cells embedded such as human umbilical vein endothelial cells (HUVECs) by HIF-1α and VEGF expression. The results of this study confirmed that in the oxygen-releasing capsule composed of H₂O₂ polymeric microspheres and catalase-bound alginate, HUVEC cells successfully survived in the hypoxic state. These results demonstrated that our oxygen producing system containing H₂O₂-PLGA microspheres could be a useful oxygenating biomaterial for engineering large-sized tissue.