Structural characteristics of polysaccharide microcapsules fromNostoc commune, and their applications in skin wound healing and pathological repair

Recent advances of chitosan as a hemostatic material: Hemostatic mechanism, material design and prospective application

Uncontrolled hemorrhage arising from surgery or trauma may cause morbidity and even mortality. Therefore, facilitating control of severe bleeding is imperative for health care worldwide. Among diverse hemostatic materials, chitosan (CS) is becoming the most promising material owing to its non-toxic feature, as well as inherently hemostatic performance. However, further enhancing hemostatic property of CS-based materials without compromising more beneficial functions remains a challenge. In this review, representative hemostatic mechanisms of CS-based materials are firstly discussed in detail, mostly including red blood cells (RBCs) aggregation, platelet adherence and aggregation, as well as interaction with plasma proteins. Also, various forms (involving powder/particle, sponge, hydrogel, nanofiber, and other forms) of CS-based hemostatic materials are systematically summarized, mainly focusing on their design and preparation, characteristics, and comparative analysis of various forms. In addition, varied hemostatic applications are described in detail, such as skin wound hemostasis, liver hemostasis, artery hemostasis, and heart hemostasis. Finally, current challenges and future directions of functional design of CS-based hemostatic materials in diverse hemostatic applications are proposed to inspire more intensive researches.

All-Aqueous Microfluidics Fabrication of Multifunctional Bioactive Microcapsules Promotes Wound Healing

Wound healing involves multiple stages of body responses, including hemostasis, inflammation, cell proliferation, and tissue remodeling. New material design satisfying all demands throughout different stages of wound healing is cherished but rarely discussed. Here we introduce all-aqueous multiphase microfluidics as a novel strategy to fabricate self-assembled, multifunctional alkylated chitosan/alginate microcapsules (SAAMs) as novel therapeutic materials for rapid blood coagulation and wound healing. SAAMs are structurally distinguished by their ultrathin shells with polycationic surface for rapid activation of clotting cascade and their internal porous dextran-rich cores for fast absorption of blood and exudate. These features endow SAAMs with excellent hemostatic properties for acute hemorrhage. Moreover, the alkylated chitosan within the microcapsules exhibits persistent antimicrobial activities against bactericidal infections due to their amphiphilic and cationic surfaces. Besides, cytokines can be safely loaded into the organic-solvent-free microcapsules and released precisely to promote the proliferation of epidermal cells, supporting the subsequent development of granulation tissue and suppression of inflammation in the last stages of wound healing. With the ability to fabricate size-tailored soft microcapsules and to realize time-sequential functions for tissue repairing, the presented "all-aqueous microfluidics generation of multifunctional bioactive SAAMs" create a versatile and robust paradigm for wound treatment.

Plant polysaccharides as novel biomaterials for microcapsule construction and therapeutics delivery

Natural polysaccharides derived from medicinal plants, that are Dendrobium (DPS), Lycium barbarum (LBP), Ginseng (GPS), and Poria Cocos (PCP) were firstly combined with sodium alginate (SA) to construct microcapsules and improved the morphology, encapsulation efficiency, Biocompatibility and protective capability in drug loading. Diverse typical therapeutics, including VO₂@ZIF67 nanoparticles, small molecule drugs salvianolic acid B (SaB)/ginsenoside (Rg1), probiotic Bacillus bifidus, and biomacromolecules SDF-1 were wrapped into 1.5 % GPS-0.5 % SA model microcapsules, respectively. Better mobility and formability were significantly observed, and showed 75 % survival rate of probiotics in simulated gastric juice and around 99 % encapsulation efficiency which is higher than single 2 % SA microcapsules. The microcapsules also obtained a delayed release and a higher cell index for SDF-1, which indicated better stability, biocompatibility and protective effect than single 2 % SA microcapsules. This study provides a strategy in developing plant derived polysaccharides as novel materials for the construction and improvement of traditional microcapsules.

Advances in polysaccharide-based nano/microcapsules for biomedical applications: A review

Biocompatible and biodegradable polysaccharides are abundant and renewable natural materials. Polysaccharides and their derivatives are developed into various carrier materials for biomedical applications. In particular, advanced polysaccharide-based nano/microcapsules have received extensive attention in biomedical applications due to their good encapsulation ability and tunability. In recent years, polysaccharide-based nano/microcapsules have been widely used in drug carriers, gene carriers, antigen carriers, wound dressings, bioimaging and biosensors. Numerous research results have confirmed the feasibility, safety, and effectiveness of polysaccharide-based nano/microcapsules in the above-mentioned biomedical applications. This review discussed and analyzed the latest research strategies and design considerations for these applications in detail. The preparation methods, application strategies, and design considerations of polysaccharide-based nano/microcapsules are summarized and analyzed, and their challenges and future research prospects in biomedicine are further discussed. It is expected to provide researchers with inspiration and design ideas.

Resveratrol Triggered the Quick Self-Assembly of Gallic Acid into Therapeutic Hydrogels for Healing of Bacterially Infected Wounds

Programing self-assembly of naturally bioactive molecules has been a wide topic of great significance for biomedical uses. Despite the fact that plant-derived polyphenols with catechol or pyrogallol moieties have been widely studied to construct nanocomplexes or nanocoatings via self-polymerization, there is no report on the self-assembly of these polyphenols into therapeutic hydrogels for potential applications. Here, we reported that adding a very small amount of resveratrol (Res) into the gallic acid (GA) aqueous solution could trigger the quick self-assembly of GA to form a fibrous hydrogel within 5 min through hydrogen bonds and π-π interactions. The length of GA/Res (GR) fibrils in gels varied from 100 to 1000 microns, with a diameter of around 1 μm. Notably, these GR hydrogels showed excellent colloid stability, providing better slow release and outstanding biocompatibility. Also, in vivo experiments indicated the hydrogels had high antibacterial effects and excellent wound healing capabilities in a total skin defect model via regulating the expression of inflammatory factors (IL-6, IL-1β, and TNF-α) due to the release of therapeutic agents (GA and Res) into the matrix. Overall, our results provide a new strategy to accelerate self-assembly of GA by adding Res to form hydrogels, which is further proved as a promising therapeutic carrier for wound healing.