Multifunctional polysaccharide/metal/polyphenol double-crosslinked hydrogel for infected wound

Calcium phytate cross-linked polysaccharide hydrogels for selective removal of U(VI) from tailings wastewater

Efficient uranium capture from rare earth tailings wastewater holds great importance for human health and sustainable development. Herein, we present a simple and eco-friendly approach to form a single network hydrogel through electrostatic interaction between chitosan and sodium alginate. Subsequently, calcium phytate is introduced as a natural crosslinking agent to generate a secondary cross-linked network, leading to a composite hydrogel (CS-SA/PCa) with a doubly enhanced network structure for efficient adsorption of uranium from wastewater. The established multistage porous structure enables the rapid diffusion of uranyl ions, and the abundant phosphate groups serving as adsorption sites can offer high affinity for U(VI). Most importantly, CS-SA/PCa is formed through physical cross-linking of sustainable biopolymers, avoiding the use of toxic chemical agents. In addition, CS-SA/PCa exhibited significantly better mechanical properties than those of single-network physical hydrogels crosslinked by electrostatic interactions, which overcame the weak mechanical properties of physical hydrogels. It provides a new method for the manufacture of environmentally friendly, low-cost and robust physical hydrogels based on natural polymers.

An adhesive, antibacterial hydrogel wound dressing fabricated by dopamine-grafted oxidized sodium alginate and methacrylated carboxymethyl chitosan incorporated with Cu(II) complex

Effective wound dressings play an important role in preventing infections and promoting wound healing. Most polysaccharide-based hydrogel dressings have the drawbacks of weak tissue adhesion and poor antibacterial properties. Herein, a multifunctional dopamine-grafted oxidized sodium alginate-methacrylated carboxymethyl chitosan/gallic acid‑copper(II) complex (OD-CM/GA-CuIIUV) hydrogel was fabricated through Schiff base bonds and photo-crosslinked polymerization between dopamine-grafted oxidized sodium alginate (OSA-DA) and methacrylated carboxymethyl chitosan (CMC-MA), with the integration of gallic acid‑copper(II) complexes (GA-CuII). The double cross-linked network and mussel-inspired adhesion mechanism endowed the hydrogel with attractive physicochemical properties, including excellent self-healing properties, pH-responsive biodegradability, robust toughness, and a maximum adhesion strength of 15.06 kPa. Moreover, the composite hydrogel exhibited an antibacterial ratio of > 99 % against Escherichia coli and Staphylococcus aureus, as well as good antioxidant activity. The MTT assay showed that the cell viability of the composite hydrogel reached > 85 %. The in vivo full-thickness skin defect healing assays in rats demonstrated that the composite hydrogel remarkably accelerated wound repair by attenuating the inflammatory response and promoting epithelial tissue remodeling. Therefore, this novel multifunctional hydrogel has potential applications in biomedical wound dressing.

All-in-one: Harnessing multifunctional natural polysaccharide spray hydrogel loaded with polyphenol-metal nanoparticles for fruit preservation

Fruit preservation materials play an instrumental role in preventing fruit deterioration and extending shelf life. However, existing fresh-keeping materials often prove inadequate in simultaneously achieving antibacterial properties, maintaining freshness, antioxidant effects, good biocompatibility, and prolonged fruit shelf life. Therefore, we present the first preparation of a natural polysaccharide spray hydrogel (Q/O/Zn hydrogel), loaded with chlorogenic acid‑zinc nanoparticles (CA@ZnNPs), utilizing quaternary ammonium insect chitosan (QECS) and oxidized pullulan (OPUL) for the preservation of perishable fruits. The findings demonstrated that the Q/O/Zn hydrogel was highly effective in inhibiting the proliferation of S. aureus and E. coli, while also exhibiting remarkable scavenging capabilities about ABTS and DPPH radicals. Furthermore, the fruit preservation trials demonstrated that the Q/O/Zn hydrogel markedly reduced fruit respiration rates, decay rates, and weight loss across various temperatures while decreasing the species diversity and abundance of harmful bacteria on fruit surfaces. The Q/O/Zn hydrogel is promising for fruit preservation.

Polyvinyl alcohol/chitosan hydrogel based on deep eutectic solvent for promoting methicillin-resistant Staphylococcus aureus-infected wound healing

Bacterial-infected wounds usually lead to slow wound healing due to increased inflammation, especially wounds infected by drug-resistant bacteria, which is a serious challenge in the biomedical field. Traditional antimicrobial strategies such as antibiotics lead to a significant increase in drug-resistant strains and have limited efficacy. Therefore, there is an urgent need to develop multifunctional dressings with excellent antibacterial activity and promotion of wound healing. In this study, the hydrogel is cross-linked by natural deep eutectic solvent (DES), polyvinyl alcohol (PVA), chitosan (CS), tannic acid (TA), and Cu2+ through intermolecular interactions (hydrogen bonds and metal coordination bonds). The hydrogel was prepared using a simple one-step mixing method without toxic chemical cross-linkers, which conformed to environmentally friendly chemistry. The prepared hydrogel had excellent injectability and self-healing properties and could fill irregular wound surfaces. In addition, in vitro studies have shown that the hydrogel has excellent hemostatic properties, good biocompatibility, and broad-spectrum antibacterial properties. Most importantly, in the methicillin-resistant Staphylococcus aureus-infected skin wound model, the hydrogel could significantly accelerate the healing of infected wounds by inhibiting the intensification of inflammation, increasing collagen deposition, accelerating re-epithelialization, and promoting the formation of hair follicles and new blood vessels.

Evolutionary research trends of polysaccharides from Polygonatum genus: A comprehensive review of its isolation, structure, health benefits, and applications

Polygonatum sibiricum, valued both as a medicinal and nutritional plant, has long been recognized for its health benefits. Increasing evidence highlights its polysaccharides (PSPs) as key components. As research into the structural characteristics and biological activity of PSPs continues to grow, there is rising interest in developing functional foods that harness their therapeutic potential. However, existing studies on PSPs remain fragmented, lacking a comprehensive framework for their application in functional food development and drug delivery. This review aims to fill that gap by systematically summarizing the purification, structural characterization, and diverse biological activities of PSPs. We also explore the significant potential of these polysaccharides in functional food development and their promising applications as natural, eco-friendly drug carriers. Furthermore, we address the key challenges and limitations in this field, offering insights into future research trends and opportunities for advancing PSPs in areas such as sustainable materials, functional foods, and therapeutic innovations.

A gelatin-chitosan-based film containing berberine hydrochloride/polypyrrole that promotes infectious wound healing through antibacterial and antioxidant properties, and electrical conductivity

Wound infections are a significant threat to human health. Therefore, the development of wound dressings with rapid antimicrobial properties is crucial to promote effective wound healing. In this study, chitosan (CS) was combined with gelatin (GE) to create an active film dressing (GC/BP) loaded with berberine hydrochloride (BH) and polypyrrole (PPY). After the incorporation of the bioactive materials, the film retained good mechanical properties, allowing it to withstand changes in the external environment of the wound. The antimicrobial effect of the GC/BP film exceeded 99 % after brief exposure to near-infrared light. In addition, the GC/BP film demonstrated a strong antioxidant effect with a DPPH clearance rate of 92.54 % within 48 h. In vivo experiments revealed that GC/BP films could enhance angiogenesis by upregulating the expression of the growth factor CD31, reducing oxidative stress by downregulating TNF-α expression, and accelerating the formation of fibrous tissues to promote wound healing. Importantly, the GC/BP film exhibited no cytotoxicity or hemolysis and demonstrated good biocompatibility. In conclusion, the GC/BP film is a safe and effective wound dressing with a promising potential for promoting wound healing.

Topical adhesive spatio-temporal nanosystem co-delivering chlorin e6 and HMGB1 inhibitor glycyrrhizic acid for in situ psoriasis chemo-phototherapy

Recently, photodynamic therapy (PDT) has gained considerable attention as a promising therapeutic approach for the treatment of psoriasis. Unfortunately, the activation of high mobility group box 1 protein (HMGB1) by PDT triggers innate and adaptive immune responses, which exacerbate skin inflammation. Herein, we combined glycyrrhizic acid (GA), a natural anti-inflammatory compound and immunomodulator derived from the herb Glycyrrhiza uralensis Fisch., with PDT actuated by the photosensitizer chlorin e6 (Ce6) by co-loading them in GA-based lipid nanoparticles coated with a catechol-modified quaternary chitosan salt (GC NPs/QCS-C). GC NPs/QCS-C exhibited high drug loading efficacy, uniform size distribution, an ideal topical adhesive property, enhanced skin retention and penetration in psoriasis-like lesions, and high intracellular uptake in epidermal cells compared with the counterparts. Subsequently, the transdermal administration of GC NPs/QCS-C followed by near-infrared laser radiation in an imiquimod-induced psoriasis-like mouse model significantly ameliorated psoriasis symptoms, promoted the apoptosis of hyperproliferative epidermal cells, and alleviated the inflammatory cascade. The significant therapeutic outcomes of GC NPs/QCS-C were attributed to the synergistic effects of GA and PDT on modulating immune cell recruitment and inhibiting dendritic cell maturation. Our results demonstrated that the topical bio-adhesive nanosystem that combines GA and Ce6 offers a synergistic chemo-phototherapeutic strategy for psoriasis treatment.

Recent advances in self-targeting natural product-based nanomedicines

Natural products, recognized for their potential in disease prevention and treatment, have been integrated with advanced nano-delivery systems to create natural product-based nanomedicines, offering innovative approaches for various diseases. Natural products derived from traditional Chinese medicine have their own targeting effect and remarkable therapeutic effect on many diseases, but there are some shortcomings such as poor physical and chemical properties. The construction of nanomedicines using the active ingredients of natural products has become a key step in the modernization research process, which could be used to make up for the defects of natural products such as low solubility, large dosage, poor bioavailability and poor targeting. Nanotechnology enhances the safety, selectivity, and efficacy of natural products, positioning natural product-based nanomedicines as promising candidates in medicine. This review outlines the current status of development, the application in different diseases, and safety evaluation of natural product-based nanomedicines, providing essential insights for further exploration of the synergy between natural products and nano-delivery systems in disease treatment.

3D nanofiber sponge based on natural insect quaternized chitosan/pullulan/citric acid for accelerating wound healing

Extensive traumatic injuries and difficult-to-heal wounds, induced by many circumstances, impose a significant social and economic burden on an annual basis. Thus, innovative wound dressings that encourage wound healing are greatly needed. In this work, we prepared a novel insect chitosan (MCS) using waste pupal shells from housefly (Musca domestica L.) culture. After conducting comparative investigations with commercially available chitosan, it was shown that MCS exhibited comparable qualities and may be used as a substitute source of commercial chitosan. A quaternized chitosan/pullulan/citric acid three-dimensional nanofiber sponge (3D-NS) of natural origin was prepared by electrostatic spinning and gas foaming techniques after MCS was quaternized. In vitro, tests showed that the 3D-NS had a higher liquid absorption capacity than the two-dimensional nanofibrous membrane (2D-NM). Additionally, the 3D-NS showed improved hemostatic, pro-cell proliferation, antibacterial, and anti-inflammatory qualities. In vitro, tests demonstrated that 3D-NS could inhibit the release of inflammatory factors, promote angiogenesis, accelerate collagen deposition, and promote wound contraction. These effects considerably facilitated the healing process of wounds in rats with full-thickness skin damage. In conclusion, the great bioactivity and physicochemical properties of 3D-NS render it an optimal candidate for developing novel wound dressings.

Multifunctional hydrogel based on polyvinyl alcohol/chitosan/metal polyphenols for facilitating acute and infected wound healing

Bacterial-infected wounds could cause delayed wound healing due to increased inflammation, especially wounds infected by drug-resistant bacteria remain a major clinical problem. However, traditional treatment strategies were gradually losing efficacy, such as the abuse of antibiotics leading to enhanced bacterial resistance. Therefore, there was an urgent need to develop an antibiotic-free multifunctional dressing for bacterially infected wound healing. This study demonstrated the preparation of a multifunctional injectable hydrogel and evaluated its efficacy in treating acute and infected wounds. The hydrogel was prepared by a one-step mixing method, and cross-linked by natural deep eutectic solvent (DES), polyvinyl alcohol (PVA), chitosan (CS), tannic acid (TA), and Cu2+ through non-covalent interactions (hydrogen bonds and metal coordination bonds). PVA/CS/DES/CuTA500 hydrogel has multiple functional properties, including injectability, tissue adhesion, biocompatibility, hemostasis, broad-spectrum antibacterial, anti-inflammatory, and angiogenesis. Most importantly, in the MRSA-infected skin wound model, PVA/CS/DES/CuTA500 hydrogel could ultimately accelerate infected wound healing by killing bacteria, activating M2 polarization, inhibiting inflammation, and promoting angiogenesis. In summary, the PVA/CS/DES/CuTA500 hydrogel showed great potential as a wound dressing for bacterial infected wounds treatment in the clinic.

Polysaccharide-Based Injectable Hydrogel Loaded with Quercetin Promotes Scarless Healing of Burn Wounds by Reducing Inflammation

Moisture loss, infection, and severe inflammatory reactions are the primary factors affecting burn wound healing and leading to scar formation. Herein, we developed a quercetin-loaded polysaccharide-based injectable hydrogel (named PECE). The PECE consists of oxidized sodium alginate (OAlg) coupled with chitosan (CS) via Schiff bases and electrostatic interactions, while Que is incorporated via hydrogen bonding. Benefiting from the hydroxyl and carboxyl groups, PECE features distinguished moisturizing ability. Additionally, the sustained release of Que imparts remarkable antibacterial activity against Escherichia coli and Staphylococcus aureus. Likewise, PECE demonstrates favorable in vitro anti-inflammatory capacity as released Que significantly downregulates pro-inflammatory factors (IL-6 and TNF-α) secreted by RAW 264.7 macrophages. More importantly, in a rat model of deep second-degree burn wounds, PECE effectively inhibits wound infection, reduces inflammation, and promotes angiogenesis and collagen deposition, ultimately minimizing scar formation. Overall, this work presents a promising strategy for scarless healing of burn wounds.

Injectable immunoregulatory hydrogels sequentially drive phenotypic polarization of macrophages for infected wound healing

Regulating macrophage phenotypes to reconcile the conflict between bacterial suppression and tissue regeneration is ideal for treating infectious skin wounds. Here, an injectable immunoregulatory hydrogel (SrmE20) that sequentially drives macrophage phenotypic polarization (M0 to M1, then to M2) was constructed by integrating anti-inflammatory components and proinflammatory solvents. In vitro experiments demonstrated that the proinflammatory solvent ethanol stabilized the hydrogel structure, maintained the phenolic hydroxyl group activity, and achieved macrophages' proinflammatory transition (M0 to M1) to enhance antibacterial effects. With ethanol depletion, the hydrogel's cations and phenolic hydroxyl groups synergistically regulated macrophages' anti-inflammatory transition (M1 to M2) to initiate regeneration. In the anti-contraction full-thickness wound model with infection, this hydrogel effectively eliminated bacteria and even achieved anti-inflammatory M2 macrophage accumulation at three days post-surgery, accelerated angiogenesis and collagen deposition. By sequentially driving macrophage phenotypic polarization, this injectable immunoregulatory hydrogel will bring new guidance for the care and treatment of infected wounds.

Formulation and evaluation of n-acetyl cysteine loaded bi-polymeric physically crosslinked hydrogel with antibacterial and antioxidant activity for diabetic wound dressing

Diabetic wounds have become a serious global health concern, with a growing number of patients each year. Diabetic altered wound healing physiology, as well as resulting complications, make therapy difficult. Hence, diabetic wound healing necessitates a multidisciplinary strategy. This study focused on the formulation, statistical optimization, ex vivo, and in vitro evaluation of a diabetic wound healing by n-acetyl cysteine (NAC) loaded hydrogel. The objective of the study is to formulate n-acetyl loaded hydrogel with different ratio (1:1, 1:2, 1:3, 2:1) of sodium alginate and guar gum. The antibacterial and antifungal assessment against the viability of Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S.aureus) and Candida albicans (C. albicans) was conducted after determining the in vitro drug release profile. The results of the experiment demonstrated that the formulation F3 was an optimal formulation on triplicate measurement with a pH of 6.2 ± 0.168, and a density of 1.026 ± 0.21. In vitro cell line study exhibited F3 has potential role in cell adhesion and proliferation might be beneficial to tissue regeneration and wound healing. The results imply that F3 may be helpful for the quick healing of diabetic wounds by promoting angiogenesis and also by scavenging free oxygen radicals.

Protamine-grafted carboxymethyl chitosan based hydrogel with adhesive and long-term antibacterial properties for hemostasis and skin wound healing

In this study, we developed a tissue-adhesive and long-term antibacterial hydrogel consisting of protamine (PRTM) grafted carboxymethyl chitosan (CMC) (PCMC), catechol groups modified CMC (DCMC), and oxidized hyaluronic acid (OHA), named DCMC-OHA-PCMC. According to the antibacterial experiments, the PCMC-treated groups showed obvious and long-lasting inhibition zones against E. coli (and S. aureus), and the corresponding diameters varied from 10.1 mm (and 15.3 mm) on day 1 to 9.8 mm (and 15.3 mm) on day 7. The DCMC-OHA-PCMC hydrogel treated groups also exhibited durable antibacterial ability against E. coli (and S. aureus), and the antibacterial rates changed from 99.3 ± 0.21 % (and 99.6 ± 0.36 %) on day 1 to 76.2 ± 1.74 % (and 84.2 ± 1.11 %) on day 5. Apart from good mechanical and tissue adhesion properties, the hydrogel had excellent hemostatic ability mainly because of the grafted positive-charged PRTM. As the animal assay results showed, the hydrogel was conducive to promoting the deposition of new collagen (0.84 ± 0.03), the regeneration of epidermis (98.91 ± 6.99 μm) and wound closure in the process of wound repairing. In conclusion, the presented outcomes underline the prospective potential of the multifunctional CMC-based hydrogel for applications in wound dressings.

Formation of Stable Vascular Networks by 3D Coaxial Printing and Schiff-Based Reaction

Vascularized organs hold potential for various applications, such as organ transplantation, drug screening, and pathological model establishment. Nevertheless, the in vitro construction of such organs encounters many challenges, including the incorporation of intricate vascular networks, the regulation of blood vessel connectivity, and the degree of endothelialization within the inner cavities. Natural polymeric hydrogels, such as gelatin and alginate, have been widely used in three-dimensional (3D) bioprinting since 2005. However, a significant disparity exists between the mechanical properties of the hydrogel materials and those of human soft tissues, necessitating the enhancement of their mechanical properties through modifications or crosslinking. In this study, we aim to enhance the structural stability of gelatin-alginate hydrogels by crosslinking gelatin molecules with oxidized pullulan (i.e., a polysaccharide) and alginate molecules with calcium chloride (CaCl2). A continuous small-diameter vascular network with an average outer diameter of 1 mm and an endothelialized inner surface is constructed by printing the cell-laden hydrogels as bioinks using a coaxial 3D bioprinter. The findings demonstrate that the single oxidized pullulan crosslinked gelatin and oxidized pullulan/CaCl2 double-crosslinked gelatin-alginate hydrogels both exhibit a superior structural stability compared to their origins and CaCl2 solely crosslinked gelatin-alginate hydrogels. Moreover, the innovative gelatin and gelatin-alginate hydrogels, which have excellent biocompatibilities and very low prices compared with other hydrogels, can be used directly for tissue/organ construction, tissue/organ repairment, and cell/drug transportation.