Alginate hydrogel dressings for advanced wound management

Polysaccharide-based hydrogels for medical devices, implants and tissue engineering: A review

Hydrogels are highly biocompatible biomaterials composed of crosslinked three-dimensional networks of hydrophilic polymers. Owing to their natural origin, polysaccharide-based hydrogels (PBHs) possess low toxicity, high biocompatibility and demonstrate in vivo biodegradability, making them great candidates for use in various biomedical devices, implants, and tissue engineering. In addition, many polysaccharides also show additional biological activities such as antimicrobial, anticoagulant, antioxidant, immunomodulatory, hemostatic, and anti-inflammatory, which can provide additional therapeutic benefits. The porous nature of PBHs allows for the immobilization of antibodies, aptamers, enzymes and other molecules on their surface, or within their matrix, potentiating their use in biosensor devices. Specific polysaccharides can be used to produce transparent hydrogels, which have been used widely to fabricate ocular implants. The ability of PBHs to encapsulate drugs and other actives has been utilized for making neural implants and coatings for cardiovascular devices (stents, pacemakers and venous catheters) and urinary catheters. Their high water-absorption capacity has been exploited to make superabsorbent diapers and sanitary napkins. The barrier property and mechanical strength of PBHs has been used to develop gels and films as anti-adhesive formulations for the prevention of post-operative adhesion. Finally, by virtue of their ability to mimic various body tissues, they have been explored as scaffolds and bio-inks for tissue engineering of a wide variety of organs. These applications have been described in detail, in this review.

Chitosan/alginate scaffold enhanced with Berberis vulgaris extract for osteocyte differentiation of ovine fetal stem cells

Designing biocompatible polymers using plant derivatives can be extremely useful in tissue engineering, nanomedicine, and many other fields of medicine. In this study, it was first looked into how chitosan/alginate scaffolds were made and characterized in the presence of berberine and barberry fruit extract. Second, the process of proliferation and differentiation of ovine fetal BM-MSCs (bone marrow-mesenchymal stem cells) was assessed on these scaffolds after BM-MSCs were extracted and confirmed by developing into osteocyte and adipose cells. To investigate the differentiation, treatment groups include (1) ovine fetal BM-MSCs were plated in Dulbecco's modified eagle medium culture medium with high glucose containing 10% fetal bovine serum and antibiotics (negative control), (2) ovine fetal BM-MSCs were plated in osteogenic differentiation medium (positive control group), (3) positive control group + barberry fruit extract, (4) positive control group + berberine, (5) ovine fetal BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate scaffold (hydrogel group), (6) ovine fetal BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/barberry fruit extract scaffold (hydrogel group containing barberry fruit extract), and (7) ovine fetal BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/berberine scaffold (hydrogel group containing berberine). Alkaline phosphatase (ALP) enzyme concentrations, mineralization rate using a calcium kit, and mineralization measurement by alizarin staining quantification were all found after 21 days of culture. In addition, real-time quantitative reverse transcription polymerase chain reaction was used to assess the expression of the ALP, COL1A2, and Runx2 genes. Days 5 and 7 had the lowest water absorption by the hydrogel scaffold containing barberry extract, which was significant in comparison to other groups (p < .05). Among the hydrogel scaffolds under study, the one containing barberry extract exhibited the lowest tensile strength, and this difference was statistically significant (p < .05). The chitosan/alginate hydrogel has the highest tensile strength of all of them. In comparison to the control and other treatment groups, the inclusion of berberine in the chitosan/alginate hydrogel significantly increased the expression of the ALP, Runx2, and COL1A2 genes (p < .05). The osteocyte differentiation of mesenchymal stem cells in in vitro settings appears to have been enhanced by the inclusion of berberine in the chitosan/alginate scaffold.

Advances in Chronic Wound Management: From Conventional Treatment to Novel Therapies and Biological Dressings

Chronic wounds can be classified as diabetic foot ulcers, pressure ulcers, or venous leg ulcers. Chronic wound management has become a threat to clinicians and constitutes a major healthcare burden. The healing process of chronic wounds requires many factors to work in concert to achieve optimal healing. Various treatment options, ranging from hypoxia to infection, have evolved considerably to address the challenges associated with chronic wound healing. The conventional and accelerating treatments for chronic wounds still represent an unmet medical need due to the complex pathophysiology of the chronic wound microenvironment. In clinical settings, traditional chronic wound care practices rely on nonspecific topical treatment, which can reduce pain and alleviate disease progression with varying levels of success but fail to completely cure the wounds. Conventional wound dressings, such as hydrocolloids, gauze, foams, and films, have also shown limited success for the treatment of chronic wounds and only act as a physical barrier and absorb wound exudates. Emerging advances in treatment approaches, including novel therapies (stem cells, microRNAs, and nanocarrier-based delivery systems) and multifunctional biological dressings, have been reported for chronic wound repair. This review summarizes the challenges offered by chronic wounds and discusses recent advancements in chronic wound treatment.

Adhesive, Flexible, and Fast Degradable 3D-Printed Wound Dressings with a Simple Composition

3D printing technology has revolutionized the field of wound dressings, offering tailored solutions with mechanical support to facilitate wound closure. In addition to personalization, the intricate nature of the wound healing process requires wound dressing materials with diverse properties, such as moisturization, flexibility, adhesion, anti-oxidation and degradability. Unfortunately, current materials used in digital light processing (DLP) 3D printing have been inadequate in meeting these crucial criteria. This study introduces a novel DLP resin that is biocompatible and consists of only three commonly employed non-toxic compounds in biomaterials, that is, dopamine, poly(ethylene glycol) diacrylate, and N-vinylpyrrolidone. Simple as it is, this material system fulfills all essential functions for effective wound healing. Unlike most DLP resins that are non-degradable and rigid, this material exhibits tunable and rapid degradation kinetics, allowing for complete hydrolysis within a few hours. Furthermore, the high flexibility enables conformal application of complex dressings in challenging areas such as finger joints. Using a difficult-to-heal wound model, the manifold positive effects on wound healing in vivo, including granulation tissue formation, inflammation regulation, and vascularization are substantiated. The simplicity and versatility of this material make it a promising option for personalized wound care, holding significant potential for future translation.

Recent progress in polysaccharide and polypeptide based modern moisture-retentive wound dressings

Wounds were considered as defects in the tissues of the human skin and wound healing is said to be a tedious process as there are possibilities of infection or inflammation due to microorganisms. Modern moisture-retentive wound dressing (MMRWD) is opening a new window toward wound therapy. It comprises different types of wound dressing that has classified based on their functionality. Selective polysaccharide-polypeptide fiber composite materials such as hydrogels, hydrocolloids, hydro fibers, transparent-film dressing, and alginate dressing are discussed in this review as a type of MMRWD. The highlight of this polysaccharide and polypeptide based MMRWD is that it supports and enhances the healing of different types of wounds by moisture absorption thus preventing infection. This study has given enlightenment on the application of selected polysaccharide and polypeptide based MMRWD that enhances wound healing actions still it has been observed that the composite wound healing dressing is more effective than the single one. The nano-sized materials (synthetic nano drugs and phyto drugs) were found to increase the efficiency of healing action while coated in the wound dressing material. Future research is required to find out more possibilities of the different composite types of wound dressing in the healing action.

Hydrogel and Nanomedicine-Based Multimodal Therapeutic Strategies for Spinal Cord Injury

Spinal cord injury (SCI) is a severe neurodegenerative disease caused by mechanical and biological factors, manifesting as a loss of motor and sensory functions. Inhibition of injury expansion and even reversal of injury in the acute damage stage of SCI are important strategies for treating this disease. Hydrogels and nanoparticle (NP)-based drugs are the most effective, widely studied, and clinically valuable therapeutic strategies in the field of repair and regeneration. Hydrogels are 3D flow structures that fill the pathological gaps in SCI and provide a microenvironment similar to that of the spinal cord extracellular matrix for nerve cell regeneration. NP-based drugs can easily penetrate the blood-spinal cord barrier, target SCI lesions, and are noninvasive. Hydrogels and NPs as drug carriers can be loaded with various drugs and biological therapeutic factors for slow release in SCI lesions. They help drugs function more efficiently by exerting anti-inflammatory, antioxidant, and nerve regeneration effects to promote the recovery of neurological function. In this review, the use of hydrogels and NPs as drug carriers and the role of both in the repair of SCI are discussed to provide a multimodal strategic reference for nerve repair and regeneration after SCI.

Rhubarb charcoal-crosslinked chitosan/silk fibroin sponge scaffold with efficient hemostasis, inflammation, and angiogenesis for promoting diabetic wound healing

Diabetic patients often experience long-term risks due to chronic inflammation and delayed re-epithelialization during impaired wound healing. Although the severity of this condition is well known, the treatment options for diabetic wounds are limited. Rhubarb charcoal, a well-known traditional Chinese medicine, has been used to treat skin wounds for thousands of years. We produced a chitosan/silk fibroin sponge scaffold loaded with natural carbonized rhubarb and crosslinked it by freeze-drying to create a highly efficient RCS/SF scaffold. Rhubarb carbon and carboxymethyl chitosan exhibit antibacterial activity and promote wound healing. Owing to its 3D porous structure, this scaffold is antibacterial and pro-angiogenic. It also possesses remarkable properties, such as excellent swelling and biocompatibility. The supportive effect of carbonized rhubarb on mouse fibroblast migration is mediated at the cellular/tissue level by increased skin neovascularization and re-epithelization. Compared to the control group, RCS/SF scaffolds promoted faster healing, increased neovascularization, enhanced collagen deposition, and re-epithelialization within two weeks. The scaffold's pro-healing properties and efficient release of carbonized rhubarb, with rapid hemostatic and good sterilization effects, make it an outstanding candidate for treating diabetic wounds and novel therapeutic interventions for diabetic ulcers.

Alginate/hyaluronic acid-based systems as a new generation of wound dressings: A review

Skin is the largest organ of the human body, which acts as a protective barrier against pathogens. Therefore, a lot of research has been carried out on wound care and healing. Creating an ideal environment for wound healing and optimizing the local and systemic conditions of the patient play critical roles in successful wound care. Many products have been developed for improving the wound environment and providing a protected and moist area for fast healing. However, there is still high demand for new systems with high efficiency. The first generation of wound dressings merely covered the wound, while the subsequent/last generations covered it and aided in healing it in different ways. In modern wound dressings, the kind of used materials and their complexity play a crucial role in the healing process. These new systems support wound healing by lowering inflammation, exudate, slough, and bacteria. This study addresses a review of alginate/hyaluronic acid-based wound dressings developed so far as well as binary and ternary systems and their role in wound healing. Our review corroborates that these systems can open up a new horizon for wounds that do not respond to usual treatments and have a long curing period.

Recent advances in double network hydrogels based on naturally-derived polymers: synthesis, properties, and biological applications

Hydrogels composed of naturally-derived biopolymers have garnered significant research interest due to the bioavailability and biocompatibility of starting materials. However, translating these advantages to practical use is challenged by limitations of mechanical properties and stability of the resulting materials. The development of double network (DN) hydrogels has led to greatly enhanced mechanical properties and shows promise toward broadening the applications of conventional synthetic or natural hydrogels. This review highlights recently developed protein-based and polysaccharide-based DN hydrogels. For each biopolymer, we focus on a subset of DN hydrogels centered around a theme related to synthetic design or applications. Network structures and crosslinking mechanisms that endow enhanced mechanical properties and performance to the materials are discussed. Important applications, including tissue engineering, drug delivery, bioadhesives, wound healing, and wearable sensors, that arise from the inherent properties of the natural polymer or its combination with other materials are also emphasized. Finally, we discuss ongoing challenges to stimulate the discovery of new design principles for the future of DN hydrogels based on naturally-derived polymers for biological applications.

An extracellular matrix mimicking alginate hydrogel scaffold manipulates an inflammatory microenvironment and improves peripheral nerve regeneration by controlled melatonin release

Low efficiency of nerve growth and unstable release of loaded drugs have become a major problem in repairing peripheral nerve injury. Many intervention strategies were focused on simple drug loading, but have still been less effective. The key challenge is to establish a controlled release microenvironment to enable adequate nerve regeneration. In this study, we fabricate a multilayered compound nerve scaffold by electrospinning: with an anti-adhesive outer layer of polycaprolactone and an ECM-like inner layer consisting of a melatonin-loaded alginate hydrogel. We characterized the scaffold, and the loaded melatonin can be found to undergo controlled release. We applied them to a 15 mm rat model of sciatic nerve injury. After 16 weeks, the animals in each group were evaluated and compared for recovery of motor function, electrophysiology, target organ atrophy status, regenerative nerve morphology and relative protein expression levels of neural markers, inflammatory oxidative stress, and angiogenesis. We identify that the scaffold can improve functional ability evidenced by an increased sciatic functional index and nerve electrical conduction level. The antioxidant melatonin loaded in the scaffold reduces inflammation and oxidative stress in the reinnervated nerves, confirmed by increased HO-1 and decreased TNF-α levels in regenerating nerves. The relative expression of fast-type myosin was elevated in the target gastrocnemius muscle. An improvement in angiogenesis facilitates neurite extension and axonal sprouting. This scaffold can effectively restore the ECM-like microenvironment and improve the quality of nerve regeneration by controlled melatonin release, thus enlightening the design criteria on nerve scaffolds for peripheral nerve injury in the future.

Extracellular vesicle biopotentiated hydrogels for diabetic wound healing: The art of living nanomaterials combined with soft scaffolds

Diabetic wounds (DWs) pose a major challenge for the public health system owing to their high incidence, complex pathogenesis, and long recovery time; thus, there is an urgent need to develop innovative therapies to accelerate the healing process of diabetic wounds. As natural nanovesicles, extracellular vesicles (EVs) are rich in sources with low immunogenicity and abundant nutritive molecules and exert potent therapeutic effects on diabetic wound healing. To avoid the rapid removal of EVs, a suitable delivery system is required for their controlled release. Owing to the advantages of high porosity, good biocompatibility, and adjustable physical and chemical properties of hydrogels, EV biopotentiated hydrogels can aid in achieving precise and favorable therapy against diabetic wounds. This review highlights the different design strategies, therapeutic effects, and mechanisms of EV biopotentiated hydrogels. We also discussed the future challenges and opportunities of using EV biopotentiated hydrogels for diabetic wound healing.

Multifunctional and theranostic hydrogels for wound healing acceleration: An emphasis on diabetic-related chronic wounds

Hydrogels represent intricate three-dimensional polymeric structures, renowned for their compatibility with living systems and their ability to naturally degrade. These networks stand as promising and viable foundations for a range of biomedical uses. The practical feasibility of employing hydrogels in clinical trials has been well-demonstrated. Among the prevalent biomedical uses of hydrogels, a significant application arises in the context of wound healing. This intricate progression involves distinct phases of inflammation, proliferation, and remodeling, often triggered by trauma, skin injuries, and various diseases. Metabolic conditions like diabetes have the potential to give rise to persistent wounds, leading to delayed healing processes. This current review consolidates a collection of experiments focused on the utilization of hydrogels to expedite the recovery of wounds. Hydrogels have the capacity to improve the inflammatory conditions at the wound site, and they achieve this by diminishing levels of reactive oxygen species (ROS), thereby exhibiting antioxidant effects. Hydrogels have the potential to enhance the growth of fibroblasts and keratinocytes at the wound site. They also possess the capability to inhibit both Gram-positive and Gram-negative bacteria, effectively managing wounds infected by drug-resistant bacteria. Hydrogels can trigger angiogenesis and neovascularization processes, while also promoting the M2 polarization of macrophages, which in turn mitigates inflammation at the wound site. Intelligent and versatile hydrogels, encompassing features such as pH sensitivity, reactivity to reactive oxygen species (ROS), and responsiveness to light and temperature, have proven advantageous in expediting wound healing. Furthermore, hydrogels synthesized using environmentally friendly methods, characterized by high levels of biocompatibility and biodegradability, hold the potential for enhancing the wound healing process. Hydrogels can facilitate the controlled discharge of bioactive substances. More recently, there has been progress in the creation of conductive hydrogels, which, when subjected to electrical stimulation, contribute to the enhancement of wound healing. Diabetes mellitus, a metabolic disorder, leads to a slowdown in the wound healing process, often resulting in the formation of persistent wounds. Hydrogels have the capability to expedite the healing of diabetic wounds, facilitating the transition from the inflammatory phase to the proliferative stage. The current review sheds light on the biological functionalities of hydrogels, encompassing their role in modulating diverse mechanisms and cell types, including inflammation, oxidative stress, macrophages, and bacteriology. Additionally, this review emphasizes the significance of smart hydrogels with responsiveness to external stimuli, as well as conductive hydrogels for promoting wound healing. Lastly, the discussion delves into the advancement of environmentally friendly hydrogels with high biocompatibility, aimed at accelerating the wound healing process.

Sodium alginate/poly(vinyl alcohol)/taxifolin nanofiber mat promoting diabetic wound healing by modulating the inflammatory response, angiogenesis, and skin flora

Diabetes-related ulcers are still a therapeutic problem because of their susceptibility to infection, ongoing inflammation, and diminished vascularization. The design and development of novel dressings are clinically urgent for the treatment of chronic wounds due to diabetic ulcers. In this study, we made taxifolin (TAX) loaded sodium alginate (SA)/poly(vinyl alcohol) (PVA) nanofibers for the treatment of chronic wounds. The SA/PVA/TAX nanofibers that have been created are smooth and bead-free, with good thermal stability, hydrophilicity, and mechanical properties. The release profile indicated a sustained drug release, with a cumulative release rate of 64.6 ± 3.7 % at 24 h. In vitro experiments have shown that SA/PVA/TAX has good antibacterial activity, antioxidant activity, and biocompatibility. In vivo experiments have shown that SA/PVA/TAX exhibits desirable biochemical properties and is involved in the diabetic wound healing process by promoting cell proliferation (Ki67), angiogenesis (CD31, VEGFA), and alleviating inflammation (CD68). Western blotting experiments suggest that SA/PVA/TAX may promote diabetic wound healing by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway and upregulating the expression of VEGFA and PDGFA. The 16S rRNA sequencing results showed that SA/PVA/TAX increased the wound surface flora's diversity and reversed the skin microbiota's structural imbalance. Therefore, SA/PVA/TAX can promote diabetic wound healing by modulating the inflammatory response, angiogenesis, and skin flora and has the potential to be an excellent wound dressing.

Blood Coagulation Activities of Cotton-Alginate-Copper Composites

Alginate-based materials have gained significant attention in the medical industry due to their biochemical properties. In this article, we aimed to synthesize Cotton-Alginate-Copper Composite Materials (COT-Alg(-)Cu(2+)). The main purpose of this study was to assess the biochemical properties of new composites in the area of blood plasma coagulation processes, including activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). This study also involved in vitro antimicrobial activity evaluation of materials against representative colonies of Gram-positive and Gram-negative bacteria and antifungal susceptibility tests. The materials were prepared by immersing cotton fibers in an aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the fibers with Cu(II) ions to yield antimicrobial activity. The results showed that the obtained cotton-alginate-copper composites were promising materials to be used in biomedical applications, e.g., wound dressing.

Poly (ε-caprolactone)-Based Scaffolds with Multizonal Architecture: Synthesis, Characterization, and In Vitro Tests

Tissue engineering is vital in treating injuries and restoring damaged tissues, aiming to accelerate regeneration and optimize the complex healing process. In this study, multizonal scaffolds, designed to mimic tissues with bilayer architecture, were prepared using the rotary jet spinning technique (RJS scaffolds). Polycaprolactone and different concentrations of alginate hydrogel (2, 4, and 6% m/v) were used. The materials were swollen in pracaxi vegetable oil (PO) (Pentaclethra macroloba) and evaluated in terms of surface morphology, wettability, functional groups, thermal behavior, crystallinity, and cytotoxicity. X-ray diffraction (XRD) showed the disappearance of the diffraction peak 2θ = 31.5° for samples from the polycaprolactone/pracaxi/alginate (PCLOA) group, suggesting a reduction of crystallinity according to the presence of PO and semi-crystalline structure. Wettability gradients (0 to 80.91°) were observed according to the deposition layer and hydrogel content. Pore diameters varied between 9.27 μm and 37.57 μm. Molecular interactions with the constituents of the formulation were observed via infrared spectra with Fourier transform (FTIR), and their influence was detected in the reduction of the maximum degradation temperature within the groups of scaffolds (polycaprolactone/alginate (PCLA) and PCLOA) about the control. In vitro tests indicated reduced cell viability in the presence of alginate hydrogel and PO, respectively.

Ions-Induced Alginate Gelation According to Elemental Analysis and a Combinatorial Approach

This study considers the potential of elemental analysis of polysaccharide ionotropic gels in elucidating the junction zones for different divalent cations. The developed algorithm ensures the correct separation of contributions from physically adsorbed and structure-forming ionic compounds, with the obtained results scaled to alginate C12 block. Possible versions of chain association into dimers and their subsequent integration into flat junction zones were analyzed within the framework of the "egg-box" model. The application of combinatorial analysis made it possible to derive theoretical relations to find the probability of various types of egg-box cell occurrences for alginate chains with arbitrary monomeric units ratio μ = M/G, which makes it possible to compare experimental data for alginates of different origins. Based on literature data and obtained chemical formulas, the possible correspondence of concrete biopolymer cells to those most preferable for filling by alkaline earth cations was established. The identified features of elemental composition suggest the formation of composite hydrated complexes with the participation of transition metal cations. The possibility of quantitatively assessing ordered secondary structures formed due to the physical sorption of ions and molecules from environment, correlating with the sorption capabilities of Me2+ alginate, was established.

Mesenchymal stem cell-derived secretomes-enriched alginate/ extracellular matrix hydrogel patch accelerates skin wound healing

BACKGROUND

The secretomes of mesenchymal stem cells (MSCs) have great therapeutic potential and thereby their efficient delivery into the target site is of particular interest. Here, we propose a new strategy of hMSCs-derived secretomes delivery for advanced wound healing upon harnessing the working principle of extracellular matrix (ECM)-growth factors interaction in vivo.

METHODS

We prepared an alginate hydrogel based wound patch, where it contains both human MSC-derived secretomes and ECM. The ECM was obtained from the decellularization of in vitro cultured human lung fibroblasts. The alginate solution was blended with ECM suspension, crosslinked, air-dried, then rehydrated with the secretomes contained in the concentrated conditioned media (CCM) as a highly saturated form of conditioned media (CM). We tested four different groups, with or without the ECM to investigate not only the role of ECM but the therapeutic effect of secretomes.

RESULTS

The secretomes reserved many, diverse bioactive factors, such as VEGF, HGF, IGFBPs, IL-6, and IL-8. Alginate/ECM/CCM (AEC) patch could hold significantly larger amount of secretomes and release them longer than the other groups. Our AEC patch was the most effective in stimulating not only cell migration and proliferation but the collagen synthesis of dermal fibroblasts in vitro. Moreover, the AEC patch-treated full-thickness skin wounds disclosed significantly better wound healing indications: cell recruitment, neovascularization, epidermis thickness, keratinocyte migration, and mature collagen deposition, as assessed via histology (H&E, Herovici staining) and immunofluorescence, respectively. In particular, our AEC patch enabled a phenotype shift of myofibroblast into fibroblast over time and led to mature blood vessel formation at 14 day.

CONCLUSIONS

We believe that ECM certainly contributed to generate a secretomes-enriched milieu via ECM-secretomes interactions and thereby such secretomes could be delivered more efficiently, exerting significant therapeutic impact either individually or collectively during wound healing process.

Encapsulating Antibiotic and Protein-Stabilized Nanosilver into Sandwich-Structured Electrospun Nanofibrous Scaffolds for MRSA-Infected Wound Treatment

With the increasing prevalence of microbial infections, which results in prolonged inflammation and delayed wound healing, the development of effective and safe antimicrobial wound dressings of multiple properties remains challenging for public health. Despite their various formats, the available developed dressings with limited functions may not fulfill the diverse demands involved in the complex wound healing process. In this study, multifunctional sandwich-structured electrospinning nanofiber membranes (ENMs) were fabricated. According to the structural composition, the obtained ENMs included a hydrophilic inner layer loaded with curcumin and gentamicin sulfate, an antibacterial middle layer consisting of bovine serum albumin stabilized silver oxide nanoparticles, and a hydrophobic outer layer. The prepared sandwich-structured ENMs (SNM) exhibited good biocompatibility and killing efficacy on Escherichia coli, Staphylococcus aureus, and Methicillin-resistant S. aureus (MRSA). In particular, transcriptomic analysis revealed that SNM inactivated MRSA by inhibiting its carbohydrate and energy metabolism and reduced the bacterial resistance by downregulating mecA. In the animal experiment, SNM showed improved wound healing efficiency by reducing the bacterial load and inflammation. Moreover, 16S rDNA sequencing results indicated that SNM treatment may accelerate wound healing without observed influence on the normal skin flora. Therefore, the constructed sandwich-structured ENMs exhibited promising potential as dressings to deal with the infected wound management.

Tunable Sulfated Alginate-based Hydrogel Platform with enhanced anti-inflammatory and antioxidant capacity for promoting burn wound repair

Amidst progressive advancements in tissue engineering, there has been a significant enhancement in the efficacy of anti-inflammatory hydrogel dressings, addressing a myriad of clinical challenges on wound healing. A frequent complication during the initial stages of deep second-degree burn wound healing is the onset of an inflammatory storm, typically occurring without effective intervention. This event disrupts normal biological healing sequences, leading to undesirable regression. In response, we have customized a tunable, multidimensional anti-inflammatory hydrogel platform based on sulfated alginates (Algs), loaded with Prussian blue (PB) nanozymes. This platform competently eliminates surplus reactive oxygen species (ROS) present in the wound bed. Algs, functioning as a mimic of sulfated glycosaminoglycans (including heparin, heparan sulfate, and chondroitin sulfate) in the extracellular matrices (ECM), demonstrate a high affinity towards inflammatory chemokines such as interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1). This affinity effectively impedes the infiltration of inflammatory cells into the wound. Concurrently, Algs markedly modulate the macrophage phenotype transition from M1 to M2. Ultimately, our potent anti-inflammatory hydrogels, which strategically target inflammatory chemokines, M1 macrophages, and ROS, successfully attenuate dysregulated hyperinflammation in wound sites. Precise immunomodulation administered to deep second-degree burn wounds in mice has demonstrated promotion of neovascular maturation, granulation tissue formation, collagen deposition, and wound closure. Our biomimetic hydrogels, therefore, represent a significant expansion in the repertoire of anti-inflammatory strategies available for clinical practice.

HE@PCL/PCE Gel-Nanofiber Dressing with Robust Self-Adhesion toward High Wound-Healing Rate via Microfluidic Electrospinning Technology

Hydrogels have attracted increasing attention in the biomedical field due to their similarity in structure and composition to natural extracellular matrices. However, they have been greatly limited by their low mechanical strength and self-adhesion for further application. Here, a gel-nanofiber material is designed for wound healing, which synergistically combines the benefits of hydrogels and nanofibers and can overcome the bottleneck of poor mechanical strength and self-adhesion in hydrogels and inadequate healing environment created by nanofibers. First, a nanofiber scaffold composed of polycaprolactone/poly(citric acid)-ε-lysine (PCL/PCE) nanofibers is fabricated via a new strategy of microfluidic electrospinning, which could provide a base for hyaluronic acid-polylysine (HE) gel growth on nanofibers. The prepared HE@PCL/PCE gel-nanofiber possesses high tensile strength (24.15 ± 1.67 MPa), excellent air permeability (656 m3/m2 h kPa), outstanding self-adhesion property, and positive hydrophilicity. More importantly, the prepared gel-nanofiber dressing shows good cytocompatibility and antibacterial properties, achieving a high wound-healing rate (92.48%) and 4.685 mm granulation growth thickness within 12 days. This material may open a promising avenue for accelerating wound healing and tissue regeneration, providing potential applications in clinical medicine.

3D bioprinting of complex tissue scaffolds with in situ homogeneously mixed alginate-chitosan-kaolin bioink using advanced portable biopen

Control of in situ 3D bioprinting of hydrogel without toxic crosslinker is ideal for tissue regeneration by reinforcing and homogeneously distributing biocompatible reinforcing agent during fabrication of large area and complex tissue engineering scaffolds. In this study, homogeneous mixing, and simultaneous 3D bioprinting of a multicomponent bioink based on alginate (AL)-chitosan (CH), and kaolin was obtained by an advanced pen-type extruder to ensure structural and biological homogeneity during the large area tissue reconstruction. The static, dynamic and cyclic mechanical properties as well as in situ self-standing printability significantly improved with the kaolin concentration for AL-CH bioink-printed samples due to polymer-kaolin nanoclay hydrogen bonding and cross-linking with less amount of calcium ions. The Biowork pen ensures better mixing effectiveness for the kaolin-dispersed AL-CH hydrogels (evident from computational fluid dynamics study, aluminosilicate nanoclay mapping and 3D printing of complex multilayered structures) than the conventional mixing process. Two different cell lines (osteoblast and fibroblast) introduced during large area multilayered 3D bioprinting have confirmed the suitability of such multicomponent bioinks for in vitro even tissue regeneration. The effect of kaolin to promote uniform growth and proliferation of the cells throughout the bioprinted gel matrix is more significant for this advanced pen-type extruder processed samples.

A general route to strong, conductive and antibacterial curdlan-based purely natural eutectohydrogels with self-assembled layer-by-layer network structure

To promote the application extension of curdlan from food industry- dominant to advanced flexible biomaterials, a novel group of purely natural curdlan gels with noticeable performance was developed through a simple heating-cooling approach, i.e., heating the dispersion of pristine curdlan in mixed acidic natural deep eutectic solvents (NADESs) and water at 60-90 °C, and cooling at ambient temperature. The NADESs employed are composed of choline chloride and natural organic acids (lactic acid as the representative). The as-developed gels (called eutectohydrogels) are not only compressible and stretchable but conductive, which traditional curdlan hydrogels are not attainable. The compressive stress at 90 % strain exceeds 2.00 ± 0.03 MPa, the tensile strength and fracture elongation reach 0.131 ± 0.002 MPa and 300 ± 9 % respectively, attributed to the distinctive, reciprocally linked self-assembled layer-by-layer network structure formed during gelation. An electric conductivity up to 2.22 ± 0.04 S‧m^-1 is achieved. The excellent mechanics and conductivity confer them good strain-sensing behavior. Additionally, the eutectohydrogels display high antibacterial activity against S. aureus (a model Gram-positive bacterium) and E. coli (a model Gram-negative bacterium). The outstanding comprehensive performance together with the purely natural attribute makes them broad application prospects in biomedical fields like flexible bioelectronics.

Polysaccharide based transdermal patches for chronic wound healing: Recent advances and clinical perspective

Polysaccharides form a major class of natural polymers with diverse applications in biomedical science and tissue engineering. One of the key thrust areas for polysaccharide materials is skin tissue engineering and regeneration, whose market is estimated to reach around 31 billion USD globally by 2030, with a compounded annual growth rate of 10.46 %. Out of this, chronic wound healing and management is a major concern, especially for underdeveloped and developing nations, mainly due to poor access to medical interventions for such societies. Polysaccharide materials have shown promising results and clinical potential in recent decades with regard to chronic wound healing. Their low cost, ease of fabrication, biodegradability, and ability to form hydrogels make them ideal candidates for managing and healing such difficult-to-heal wounds. The present review presents a summary of the recently explored polysaccharide-based transdermal patches for managing and healing chronic wounds. Their efficacy and potency of healing both as active and passive wound dressings are evaluated in several in-vitro and in-vivo models. Finally, their clinical performances and future challenges are summarized to draw a road map towards their role in advanced wound care.

Alginate and Nanocellulose Dressings With Extract From Salmon Roe Reduce Inflammation and Accelerate Healing of Porcine Burn Wounds

Partial-thickness thermal burn wounds are characterized by a prolonged inflammatory response, oxidative stress, tissue damage, and secondary necrosis. An optimal dressing for burn wounds would reduce inflammation and oxidative stress while providing a moist, absorbent, and protective cover. We have developed an extract from unfertilized salmon roe containing components with potential anti-inflammatory and antioxidative properties, called HTX. HTX has been combined with alginate from brown algae and nanocellulose from tunicates, and 3D printed into a solid hydrogel wound dressing called Collex. Here, Collex was tested on partial thickness burn wounds in Göttingen minipigs compared to Jelonet, and a variant of Collex without HTX. We found that dermal treatment of burn wounds with Collex resulted in accelerated healing at a majority of measured points over 23 days, compared to treatment with Jelonet. In comparison to Collex without HTX, Collex enhanced healing in the first week after trauma where wound progression was pronounced. Notably, Collex reduced the inflammatory response in the early post-injury phase. The anti-inflammatory response of Collex was investigated in more detail on activated M1 macrophages. We found that Collex, as well as HTX alone, significantly reduced the secretion of pro-inflammatory interleukin-1β as well as intracellular levels of oxidative stress. The results from this study indicate that Collex is a potent dressing for the treatment of burn wounds, with the anti-inflammatory effect of HTX beneficial in the initial phase, and the moist qualities of the hydrogel favorable both in the initial and the proceeding proliferative phase of wound healing.

Chitin Nanofibrils Enabled Core-Shell Microcapsules of Alginate Hydrogel

An engineered 3D architectural network of the biopolymeric hydrogel can mimic the native cell environment that promotes cell infiltration and growth. Among several bio-fabricated hydrogel structures, core-shell microcapsules inherit the potential of cell encapsulation to ensure the growth and transport of cells and cell metabolites. Herein, a co-axial electrostatic encapsulation strategy is used to create and encapsulate the cells into chitin nanofibrils integrated alginate hydrogel microcapsules. Three parameters that are critical in the electrostatic encapsulation process, hydrogel composition, flow rate, and voltage were optimized. The physicochemical characterization including structure, size, and stability of the core-shell microcapsules was analyzed by scanning electron microscope (SEM), FTIR, and mechanical tests. The cellular responses of the core-shell microcapsules were evaluated through in vitro cell studies by encapsulating NIH/3T3 fibroblast cells. Notably, the bioactive microcapsule showed that the cell viability was found excellent for more than 2 weeks. Thus, the results of this core-shell microcapsule showed a promising approach to creating 3D hydrogel networks suitable for different biomedical applications such as in vitro tissue models for toxicity studies, wound healing, and tissue repair.

Polysaccharide-based hydrogel promotes skin wound repair and research progress on its repair mechanism

Polysaccharides, being a natural, active, and biodegradable polymer, have garnered significant attention due to their exceptional properties. These properties make them ideal for creating multifunctional hydrogels that can be used as wound dressings for skin injuries. Polysaccharide hydrogel has the ability to both simulate the natural extracellular matrix, promote cell proliferation, and provide a suitable environment for wound healing while protecting it from bacterial invasion. Polysaccharide hydrogels offer a promising solution for repairing damaged skin. This review provides an overview of the mechanisms involved in skin damage repair and emphasizes the potential of polysaccharide hydrogels in this regard. For different skin injuries, polysaccharide hydrogels can play a role in promoting wound healing. However, we still need to conduct more research on polysaccharide hydrogels to provide more possibilities for skin damage repair.

Hydrogel-based treatments for spinal cord injuries

Spinal cord injury (SCI) is characterized by damage resulting in dysfunction of the spinal cord. Hydrogels are common biomaterials that play an important role in the treatment of SCI. Hydrogels are biocompatible, and some have electrical conductivity that are compatible with spinal cord tissues. Hydrogels have a high drug-carrying capacity, allowing them to be used for SCI treatment through the loading of various types of active substances, drugs, or cells. We first discuss the basic anatomy and physiology of the human spinal cord and briefly discuss SCI and its treatment. Then, we describe different treatment strategies for SCI. We further discuss the crosslinking methods and classification of hydrogels and detail hydrogel biomaterials prepared using different processing methods for the treatment of SCI. Finally, we analyze the future applications and limitations of hydrogels for SCI. The development of biomaterials opens up new possibilities and options for the treatment of SCI. Thus, our findings will inspire scholars in related fields and promote the development of hydrogel therapy for SCI.

Wound Dressing Double-Crosslinked Quick Self-Healing Hydrogel Based on Carboxymethyl Chitosan and Modified Nanocellulose

The use of hydrogels in wound dressings, which is pivotal for effective wound treatment, has been widely applied to diverse medical wound conditions. However, formulating natural hydrogels that combine robust strength and self-healing capabilities is a significant challenge. To overcome this, we successfully designed a natural nanocellulose self-healing hydrogel that can quickly self-heal and restore the complete hydrogel structure after injury to fill the injured area and protect the wound from external damage. Our study utilized modified natural polymer carboxymethyl chitosan (CMC), hydrazide-modified carboxymethyl cellulose nanofibers (HCNF), and cellulose nanocrystals modified by dialdehyde (DACNC) to fabricate the hydrogel. The amides containing more amino groups and HCNF in CMC can be used as cross-linking nodes, and the high aspect ratio and specific surface area of DACNC are favorable for the connection of many active hydrogels. The hydrogel is crosslinked by the dynamic imide bond and hydrazone bond between the amino group of CMC, the amide of HCNF, and the aldehyde of DACNC and has a double network structure. These connections can be readily reassembled when disrupted, enabling fast self-healing of hydrogels within five minutes. Moreover, HCNF and DACNC were incorporated as nano-reinforced fillers to bolster the hydrogel's strength while preserving its high liquid absorption capacity (381% equilibrium swelling rate).

Phenotypically complex living materials containing engineered cyanobacteria

The field of engineered living materials lies at the intersection of materials science and synthetic biology with the aim of developing materials that can sense and respond to the environment. In this study, we use 3D printing to fabricate a cyanobacterial biocomposite material capable of producing multiple functional outputs in response to an external chemical stimulus and demonstrate the advantages of utilizing additive manufacturing techniques in controlling the shape of the fabricated photosynthetic material. As an initial proof-of-concept, a synthetic riboswitch is used to regulate the expression of a yellow fluorescent protein reporter in Synechococcus elongatus PCC 7942 within a hydrogel matrix. Subsequently, a strain of S. elongatus is engineered to produce an oxidative laccase enzyme; when printed within a hydrogel matrix the responsive biomaterial can decolorize a common textile dye pollutant, indigo carmine, potentially serving as a tool in environmental bioremediation. Finally, cells are engineered for inducible cell death to eliminate their presence once their activity is no longer required, which is an important function for biocontainment and minimizing environmental impact. By integrating genetically engineered stimuli-responsive cyanobacteria in volumetric 3D-printed designs, we demonstrate programmable photosynthetic biocomposite materials capable of producing functional outputs including, but not limited to, bioremediation.

Bio-based polymers containing traditional medicinal fillers for wound healing applications - An evaluation of neoteric development and future perspectives

In recent years, health-care providers have seen more patients with difficult-to-treat wounds and burns. The biopolymer-based wound dressing protects the wounded area while assisting in the recovery of dermal and epithelial tissues throughout the healing process. The overall number of patients with chronic lesions has been expanding due to developing society, over weight, and cardiovascular illness. For the treatment of chronic wounds, there is an increasing demand for the development of ideal wound dressing materials with excellent properties such as antibacterial activity, biocompatibility, free radical scavenging capacity, non-adherent property, hydrophilicity, and so on. Nevertheless, owing to the above mention properties, natural polymers are being used for several key functions of biomedicine like narcotic distribution systems, tissue manufacturing, bandages, and so on. Accordingly, the significance of these bio-based polymers interfered with healing functions that lead to informing and inspiring youth and scientist researchers worldwide to grab with these far-reaching areas of medicine and biology. The review highlights the physiochemical properties of natural polymers, the biological evaluation of various materials as wound dressings, their synthesis and mechanical properties, clinical status, challenges, and future perspectives.

Plasma Modification Techniques for Natural Polymer-Based Drug Delivery Systems

Natural polymers have attracted significant attention in drug delivery applications due to their biocompatibility, biodegradability, and versatility. However, their surface properties often limit their use as drug delivery vehicles, as they may exhibit poor wettability, weak adhesion, and inadequate drug loading and release. Plasma treatment is a promising surface modification technique that can overcome these limitations by introducing various functional groups onto the natural polymer surface, thus enhancing its physicochemical and biological properties. This review provides a critical overview of recent advances in the plasma modification of natural polymer-based drug delivery systems, with a focus on controllable plasma treatment techniques. The review covers the fundamental principles of plasma generation, process control, and characterization of plasma-treated natural polymer surfaces. It discusses the various applications of plasma-modified natural polymer-based drug delivery systems, including improved biocompatibility, controlled drug release, and targeted drug delivery. The challenges and emerging trends in the field of plasma modification of natural polymer-based drug delivery systems are also highlighted. The review concludes with a discussion of the potential of controllable plasma treatment as a versatile and effective tool for the surface functionalization of natural polymer-based drug delivery systems.

Accelerated Healing of Infected Diabetic Wounds by a Dual-Layered Adhesive Film Cored with Microsphere-Loaded Hydrogel Composite Dressing

Diabetic wounds, a prevalent chronic disease, are associated with older age. The hyperglycemic microenvironment in diabetic wounds significantly reduces the immune system, inducing bacterial invasion. The coupling of tissue repair and antibacterial treatment is critical for infected diabetic ulcer regeneration. In this study, a dual-layered sodium alginate/carboxymethyl chitosan (SA/CMCS) adhesive film cored with an SA-bFGF microsphere-loaded small intestine submucosa (SIS) hydrogel composite dressing with a graphene oxide (GO)-based antisense transformation system was developed to promote infected diabetic wound healing and bacterial eradication. Initially, our injectable SIS-based hydrogel composite stimulated angiogenesis, collagen deposition, and immunoregulation in diabetic wound repair. The GO-based transformation system subsequently inhibited bacterial viability in infected wounds by post-transformation regulation. Meanwhile, the SA/CMCS film provided stable adhesion covering the wound area to maintain a moist microenvironment, which promoted in situ tissue repair. Our findings provide a promising clinical translation strategy for promoting the healing of infected diabetic wounds.

A Microfluidic Approach for Synthesis of Silver Nanoparticles as a Potential Antimicrobial Agent in Alginate-Hyaluronic Acid-Based Wound Dressings

The recognized antimicrobial activity of silver nanoparticles is a well-studied property, especially when designing and developing biomaterials with medical applications. As biological activity is closely related to the physicochemical characteristics of a material, aspects such as particle morphology and dimension should be considered. Microfluidic systems in continuous flow represent a promising method to control the size, shape, and size distribution of synthesized nanoparticles. Moreover, using microfluidics widens the synthesis options by creating and controlling parameters that are otherwise difficult to maintain in conventional batch procedures. This study used a microfluidic platform with a cross-shape design as an innovative method for synthesizing silver nanoparticles and varied the precursor concentration and the purging speed as experimental parameters. The compositional and microstructural characterization of the obtained samples was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Four formulations of alginate-based hydrogels with the addition of hyaluronic acid and silver nanoparticles were obtained to highlight the antimicrobial activity of silver nanoparticles and the efficiency of such a composite in wound treatment. The porous structure, swelling capacity, and biological properties were evaluated through physicochemical analysis (FT-IR and SEM) and through contact with prokaryotic and eukaryotic cells. The results of the physicochemical and biological investigations revealed desirable characteristics for performant wound dressings (i.e., biocompatibility, appropriate porous structure, swelling rate, and degradation rate, ability to inhibit biofilm formation, and cell growth stimulation capacity), and the obtained materials are thus recommended for treating chronic and infected wounds.

Preparation and evaluation of a novel alginate-arginine-zinc ion hydrogel film for skin wound healing

In this paper, the mixed solution of sodium alginate (SA) and arginine (Arg) was dried into a film and then crosslinked with zinc ion to form sodium alginate-arginine-zinc ion (SA-Arg-Zn²⁺) hydrogel for skin wound dressings. SA-Arg-Zn²⁺ hydrogel had higher swelling ability, which was beneficial to absorbing wound exudate. Moreover, it exhibited antioxidant activity and strong inhibition against E. coli and S. aureus, and had no obvious cytotoxicity to NIH 3T3 fibroblasts. Compared with other dressings utilized in rat skin wound, SA-Arg-Zn²⁺ hydrogel showed better wound healing efficacy and the wound closure ratio reached to 100 % on the 14th day. The result of Elisa test indicated that SA-Arg-Zn²⁺ hydrogel down-regulated the expression of inflammatory factors (TNF-α and IL-6) and promoted the growth factor levels (VEGF and TGF-β₁). Furthermore, H&E staining results confirmed that SA-Arg-Zn²⁺ hydrogel could reduce wound inflammation and accelerate re-epithelialization, angiogenesis and wound healing. Therefore, SA-Arg-Zn²⁺ hydrogel is an effective and innovative wound dressing, moreover, the preparation technique is simple and feasible for industrial application.

Protein Adsorption, Calcium-Binding Ability, and Biocompatibility of Silver Nanoparticle-Loaded Polyvinyl Alcohol (PVA) Hydrogels Using Bone Marrow-Derived Mesenchymal Stem Cells

Several approaches have evolved to facilitate the exploration of hydrogel systems in biomedical research. In this sense, poly(vinyl alcohol) (PVA) has been widely used in hydrogel (HG) fabrication for several therapeutic applications. The biological properties of PVA hydrogels (PVA-HGs) are highly dependent on their interaction with protein receptors and extracellular matrix (mainly calcium) deposition, for which there is not enough evidence from existing research yet. Thus, for the first time, the functional properties, like protein and mineral interactions, related to the proliferation of mesenchymal stem cells (MSCs) by silver nanoparticle (AgNP)-loaded PVA hydrogels (AgNPs-PVA-HGs) were investigated in the present study. The UV absorption spectrum and TEM microscopic results showed a maximum absorbance of synthesized AgNPs at 409 nm, with an average particle size of 14.5 ± 2.5 nm, respectively. The functional properties, such as the calcium-binding and the protein adsorption of PVA-HG, were accelerated by incorporating AgNPs; however, the swelling properties of the HGs were reduced by AgNPs, which might be due to the masking of the free functional groups (hydroxyl groups of PVA) by AgNPs. SEM images showed the presence of AgNPs with a more porous structure in the HGs. The proliferative effect of MSCs increased over culture time from day 1 to day 7, and the cell proliferative effect was upregulated by HGs with more pronounced AgNPs-PVA-HG. In addition, both HGs did not produce any significant cytotoxicity in the MSCs. The histological (bright light and H&E staining) and fluorescence microscopic images showed the presence of a cytoskeleton and the fibrillar structure of the MSCs, and the cells adhered more firmly to all HGs. More fibrillar bipolar and dense fibrillar structures were seen in the day 1 and day 7 cultures, respectively. Interestingly, the MSCs cultured on AgNPs-PVA-HG produced extracellular matrix deposition on day 7. Accordingly, the present results proved the biocompatibility of AgNPs-PVA-HG as a suitable system for culturing mammalian stem cells for regenerative tissue applications.

Development of an All-Marine 3D Printed Bioactive Hydrogel Dressing for Treatment of Hard-to-Heal Wounds

Current standard wound care involves dressings that provide moisture and protection; however, dressings providing active healing are still scarce and expensive. We aimed to develop an ecologically sustainable 3D printed bioactive hydrogel-based topical wound dressing targeting healing of hard-to-heal wounds, such as chronic or burn wounds, which are low on exudate. To this end, we developed a formulation composed of renewable marine components; purified extract from unfertilized salmon roe (heat-treated X, HTX), alginate from brown seaweed, and nanocellulose from tunicates. HTX is believed to facilitate the wound healing process. The components were successfully formulated into a 3D printable ink that was used to create a hydrogel lattice structure. The 3D printed hydrogel showed a HTX release profile enhancing pro-collagen I alpha 1 production in cell culture with potential of promoting wound closure rates. The dressing has recently been tested on burn wounds in Göttingen minipigs and shows accelerated wound closure and reduced inflammation. This paper describes the dressings development, mechanical properties, bioactivity, and safety.

Innovative Functional Biomaterials as Therapeutic Wound Dressings for Chronic Diabetic Foot Ulcers

The imbalance of local and systemic factors in individuals with diabetes mellitus (DM) delays, or even interrupts, the highly complex and dynamic process of wound healing, leading to diabetic foot ulceration (DFU) in 15 to 25% of cases. DFU is the leading cause of non-traumatic amputations worldwide, posing a huge threat to the well-being of individuals with DM and the healthcare system. Moreover, despite all the latest efforts, the efficient management of DFUs still remains a clinical challenge, with limited success rates in treating severe infections. Biomaterial-based wound dressings have emerged as a therapeutic strategy with rising potential to handle the tricky macro and micro wound environments of individuals with DM. Indeed, biomaterials have long been related to unique versatility, biocompatibility, biodegradability, hydrophilicity, and wound healing properties, features that make them ideal candidates for therapeutic applications. Furthermore, biomaterials may be used as a local depot of biomolecules with anti-inflammatory, pro-angiogenic, and antimicrobial properties, further promoting adequate wound healing. Accordingly, this review aims to unravel the multiple functional properties of biomaterials as promising wound dressings for chronic wound healing, and to examine how these are currently being evaluated in research and clinical settings as cutting-edge wound dressings for DFU management.

Probiotic-loaded calcium alginate/fucoidan hydrogels for promoting oral ulcer healing

Probiotics are beneficial bacteria located in the oral cavity which exhibit antimicrobial properties and contribute to the regulation of immune function and the modulation of tissue repair. Fucoidan (FD), a marine prebiotic, may further enhance the ability of probiotics to promote ulcer healing. However, neither FD nor probiotics are attached to the oral cavity and neither are well-suited for oral ulcer healing owing to the wet and highly dynamic environment. In this study, probiotic-loaded calcium alginate/fucoidan composite hydrogels were developed for use as bioactive oral ulcer patches. The well-shaped hydrogels exhibited remarkable wet-tissue adhesion, suitable swelling and mechanical properties, sustained probiotic release, and excellent storage durability. Moreover, in vitro biological assays demonstrated that the composite hydrogel exhibited excellent cyto/hemocompatibility and antimicrobial effects. Importantly, compared to commercial oral ulcer patches, bioactive hydrogels show superior therapeutic capability for promoting ulcer healing in vivo by enhancing cell migration, inducing epithelial formation and orderly collagen fiber deposition, as well as facilitating neovascularization. These results demonstrate that this novel composite hydrogel patch demonstrates great potential for the treatment of oral ulcerations.

Antibacterial and Cytocompatible pH-Responsive Peptide Hydrogel

A short peptide, FHHF-11, was designed to change stiffness as a function of pH due to changing degree of protonation of histidines. As pH changes in the physiologically relevant range, G' was measured at 0 Pa (pH 6) and 50,000 Pa (pH 8). This peptide-based hydrogel is antimicrobial and cytocompatible with skin cells (fibroblasts). It was demonstrated that the incorporation of unnatural AzAla tryptophan analog residue improves the antimicrobial properties of the hydrogel. The material developed can have a practical application and be a paradigm shift in the approach to wound treatment, and it will improve healing outcomes for millions of patients each year.

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

A 3D-Printed Wound-Healing Material Composed of Alginate Dialdehyde-Gelatin Incorporating Astaxanthin and Borate Bioactive Glass Microparticles

In this study, a wound dressing composed of an alginate dialdehyde-gelatin (ADA-GEL) hydrogel incorporated by astaxanthin (ASX) and 70B (70:30 B₂O₃/CaO in mol %) borate bioactive glass (BBG) microparticles was developed through 3D printing. ASX and BBG particles stiffened the composite hydrogel construct and delayed its in vitro degradation compared to the pristine hydrogel construct, mainly due to their cross-linking role, likely arising from hydrogen bonding between the ASX/BBG particles and ADA-GEL chains. Additionally, the composite hydrogel construct could hold and deliver ASX steadily. The composite hydrogel constructs codelivered biologically active ions (Ca and B) and ASX, which should lead to a faster, more effective wound-healing process. As shown through in vitro tests, the ASX-containing composite hydrogel promoted fibroblast (NIH 3T3) cell adhesion, proliferation, and vascular endothelial growth factor expression, as well as keratinocyte (HaCaT) migration, thanks to the antioxidant activity of ASX, the release of cell-supportive Ca²⁺ and B³⁺ ions, and the biocompatibility of ADA-GEL. Taken together, the results show that the ADA-GEL/BBG/ASX composite is an attractive biomaterial to develop multipurposed wound-healing constructs through 3D printing.

Bio-Inspired Low-Cost Fabrication of Stretchable, Adhesive, Transparent, and Multi-Functionalized Joint Wound Dressings

Ideal joint wound dressings should not only promote wound healing and have good mechanical properties including stretchability and adhesion but also possess functions such as sterilization or motion monitoring. The multiple characteristic requirements have greatly limited the material's alternative, resulting in research on functional joint wound dressings falling far short of market demand. Therefore, low-cost, comprehensive designs need to be developed. Herein, inspired by the spiral arteries in the endometrium, alginate-based helical fibers were introduced into polyacrylamide/gelatin (PAM-Gel) to obtain composite polymer membranes, realizing a combination of both mechanical and functional properties. Large scale (100 m) and high-throughput (10 times higher than literature) fabrication of helical microfibers were first achieved, ensuring the low cost of fiber preparation. The composite film had adequate stretchability (>300% strain), adhesion strength (14 kPa), high transparency, and good biocompatibility. The helical fibers could be easily functionalized without affecting the mechanical properties of the dressings, thus broadening the range of materials available for joint dressings. After different treatments of the helical fibers, controlled drug release and joint motion monitoring were realized. Therefore, this helical microfiber composite membrane design achieved low-cost preparation, good mechanical properties, and functionalities including healing promotion, drug release, and motion monitoring ability, demonstrating application potential.

A new approach to the development and assessment of doxorubicin-loaded nanoliposomes for the treatment of osteosarcoma in 2D and 3D cell culture systems

Doxorubicin (DOX) is an effective anticancer drug used for the treatment of osteosarcoma. Liposomal nanocarriers for doxorubicin administration are now regarded as one of the most promising approaches to overcome multiple drug resistance and adverse side effects. The use of hydrogel as a 3D scaffold to mimic the cellular environment and provide comparable biological conditions for deeper investigations of cellular processes has attracted considerable attention. This study aimed to evaluate the impact of liposomal doxorubicin on the osteosarcoma cell line in the presence of alginate hydrogel as a three-dimensional scaffold. Different liposomal formulations based on cholesterol, phospholipids, and surfactants containing doxorubicin were developed using the thin-layer hydration approach to improve therapeutic efficacy. The final selected formulation was superficially modified using DSPE-mPEG2000. A three-dimensional hydrogel culture model with appropriate structure and porosity was synthesized using sodium alginate and calcium chloride as crosslinks for hydrogel. Then, the physical properties of liposomal formulations, such as mechanical and porosity, were characterized. The toxicity of the synthesized hydrogel was also assessed. Afterward, the cytotoxicity of nanoliposomes was analyzed on the Saos-2 and HFF cell lines in the presence of a three-dimensional alginate scaffold using the MTT assay. The results indicated that the encapsulation efficiency, the amount of doxorubicin released within 8 h, the mean size of vesicles, and the surface charge were 82.2%, 33.0%, 86.8 nm, and -4.2 mv, respectively. As a result, the hydrogel scaffolds showed sufficient mechanical resistance and suitable porosity. The MTT assay demonstrated that the synthesized scaffold had no cytotoxicity against cells, while nanoliposomal DOX exhibited marked toxicity against the Saos-2 cell line in the 3D culture medium of alginate hydrogel compared to the free drug in the 2D culture medium. Our research showed that the 3D culture model physically resembles the cellular matrix, and nanoliposomal DOX with proper size could easily penetrate into cells and cause higher cytotoxicity compared to the 2D cell culture.

Structures, Properties, and Bioengineering Applications of Alginates and Hyaluronic Acid

In recent years, polymeric materials have been used in a wide range of applications in a variety of fields. In particular, in the field of bioengineering, the use of natural biomaterials offers a possible new avenue for the development of products with better biocompatibility, biodegradability, and non-toxicity. This paper reviews the structural and physicochemical properties of alginate and hyaluronic acid, as well as the applications of the modified cross-linked derivatives in tissue engineering and drug delivery. This paper summarizes the application of alginate and hyaluronic acid in bone tissue engineering, wound dressings, and drug carriers. We provide some ideas on how to replace or combine alginate-based composites with hyaluronic-acid-based composites in tissue engineering and drug delivery to achieve better eco-economic value.

Optimization strategies of mesenchymal stem cell-based therapy for acute kidney injury

Considering the high prevalence and the lack of targeted pharmacological management of acute kidney injury (AKI), the search for new therapeutic approaches for it is in urgent demand. Mesenchymal stem cells (MSCs) have been increasingly recognized as a promising candidate for the treatment of AKI. However, clinical translation of MSCs-based therapies is hindered due to the poor retention and survival rates as well as the impaired paracrine ability of MSCs post-delivery. To address these issues, a series of strategies including local administration, three-dimensional culture, and preconditioning have been applied. Owing to the emergence and development of these novel biotechnologies, the effectiveness of MSCs in experimental AKI models is greatly improved. Here, we summarize the different approaches suggested to optimize the efficacy of MSCs therapy, aiming at promoting the therapeutic effects of MSCs on AKI patients.

Synthesis and characterization of natural fibers reinforced alginate hydrogel fibers loaded with diclofenac sodium for wound dressings

Hydrogels which become increasingly important in the biomedical field are composed of a three-dimensional hydrophilic network. Pure hydrogels are usually weak and brittle; therefore, reinforcements are assimilated into the hydrogel structure to improve the mechanical strength of the hydrogels. However, even if mechanical properties are enhanced, drapability remains an issue. In that regard, natural fiber-reinforced composite hydrogel fibers for wound dressing application are investigated in this study. Kapok and hemp fibers were used as reinforcement to improve the strength of hydrogel fibers. The properties of the prepared composite hydrogel fibers were studied with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimeter (DSC). The effect of alginate concentration and fiber weight percent on the mechanical characteristics and water absorbency was studied. Diclofenac sodium drug was loaded in the hydrogel fibers and investigated the drug release as well as antibacterial characteristics. Both fibers' reinforcement enhanced the strength of the alginate hydrogel fiber, but hemp reinforcement showed better mechanical properties. Kapok reinforcement resulted in a maximum tensile strength of 174 cN (1.24 % elongation) and 432 % exudate absorbency, while hemp reinforcement resulted in 185 cN (1.48 % elongation) and 435 % exudate absorbency. Statistical analysis revealed significant effects of sodium alginate concentration on tensile strength (p-value 0.042) and exudate absorbency (p-value 0.020) and of reinforcement (wt%) on exudate absorbency (p-value 0.043). Therefore, these composite hydrogel fibers with improved mechanical properties are capable of drug release and exhibit antibacterial effectiveness, making them a promising option for use as wound dressings.

Multifunctional thermosensitive hydrogel based on alginate and P(NIPAM-co-HEMIN) composites for accelerated diabetic wound healing

Non-healing wounds in patients with diabetes are a concerning issue associated with amputation and a high mortality rate. These wounds are exacerbated by oxidative stress and microbial infections resulting from hyperglycemia. Therefore, advanced materials for repairing wound beds must be identified urgently. This paper introduces a topically applicable composite hydrogel with thermosensitive properties and presents the antibacterial and antioxidant activities in mice with diabetes-induced wounds. This composite is developed by combining poly N-isopropyl acrylamide (NIPAM)-copolymerized HEMIN (NIPAM-co-HEMIN) and amine-modified alginate (ALG-EDA) biomaterials, with Ag nanoparticles (AgNPs) incorporated into the system as an antibacterial agent. Results of antibacterial tests show that the p(NIPAM-co-HEMIN)/ALG-EDA/AgNP composite system is effective against E. coli and S. aureus. Additionally, the AgNP composite exhibits low cellular toxicity in NIH3T3 and CT-2A cell lines. The wounds in diabetic mice treated with the composite system healed in <12 days, and the composite system accelerated the healing process by increasing collagen synthesis. In conclusion, the biocomposite reported herein is highly promising for repairing diabetic skin wounds and treating infections caused by bacterial microbes.

Injectable sodium alginate hydrogel loaded with plant polyphenol-functionalized silver nanoparticles for bacteria-infected wound healing

A novel injectable hydrogel dressing (GA@AgNPs-SA) with long-term antimicrobial effect is developed that can accelerate the closure of bacteria-infected wounds. The hydrogel dressing was prepared by cross-linking sodium alginate molecular chains and gallic acid functionalized silver nanoparticles (GA@AgNPs) via calcium ions to form a three-dimensional network. The hydrogel dressing demonstrates excellent biocompatibility and can achieve a sustainable release of silver ions, ensuring a long-term antibacterial activity and inhibiting biofilm formation. Moreover, an in vivo study demonstrates that the GA@AgNPs-SA hydrogel can effectively decrease the expression of IL-6 and TNF-α to alleviate the inflammatory response, and promote angiogenesis by upregulating CD31, α-SMA and VEGF expression, thus significantly accelerating the repair of infected wounds. Given these interesting properties, this antibacterial hydrogel has great potential for application in the clinical care of bacteria-infected wounds.

In Situ Electrospinning of "Dry-Wet" Conversion Nanofiber Dressings for Wound Healing

Rapid wound dressings provide an excellent solution strategy for the treatment of wounds in emergency situations. In this study, aqueous solvent-based PVA/SF/SA/GelMA nanofiber dressings fabricated by a handheld electrospinning device could deposit quickly and directly on the wound, perfectly fitting wounds with various sizes. Using an aqueous solvent overcame the disadvantage of using the current organic solvents as the medium for rapid wound dressings. The porous dressings had excellent air permeability to ensure smooth gas exchange at the wound site. The distribution range of the tensile strength of the dressings was 9-12 Kpa, and the tensile strain was between 60-80%, providing sufficient mechanical support during wound healing. The dressings could absorb 4-8 times their own weight in solution and could rapidly absorb wound exudates from wet wounds. The nanofibers formed ionic crosslinked hydrogel after absorbing exudates, maintaining the moist condition. It formed a hydrogel-nanofiber composite structure with un-gelled nanofibers and combined the photocrosslinking network to maintain a stable structure at the wound location. The in vitro cell culture assay indicated that the dressings had excellent cell cytocompatibility, and the addition of SF contributed to cell proliferation and wound healing. The in situ deposited nanofiber dressings had excellent potential in the urgent treatment of emergency wounds.

Scientometric Research on Trend Analysis of Nano-Based Sustained Drug Release Systems for Wound Healing

Nanomaterials, such as the nanoparticle (NP), nanomicelle, nanoscaffold, and nano-hydrogel, have been researched as nanocarriers for drug delivery more and more recently. Nano-based drug sustained release systems (NDSRSs) have been used in many medical fields, especially wound healing. However, as we know, no scientometric analysis has been seen on applying NDSRSs in wound healing, which could be of great importance to the relevant researchers. This study collected publications from 1999 to 2022 related to NDSRSs in wound healing from the Web of Science Core Collection (WOSCC) database. We employed scientometric methods to comprehensively analyze the dataset from different perspectives using CiteSpace, VOSviewer, and Bibliometrix. The results indicated that China published the most significant number of documents in the last two decades, Islamic Azad Univ was the most productive institution, and Jayakumar, R was the most influential author. Regarding the analysis of keywords, trend topics indicate that "antibacterial", "chitosan (CS)", "scaffold", "hydrogel", "silver nanoparticle", and "growth factors (GFs)" are the hot topics in recent years. We anticipate that our work will provide a comprehensive overview of research in this field and help scholars better understand the research hotspots and frontiers in this area, thus inspiring further explorations in the future.