New injectable chitosan-hyaluronic acid based hydrogels for hemostasis and wound healing

Development of novel iron(III) crosslinked bioinks comprising carboxymethyl cellulose, xanthan gum, and hyaluronic acid for soft tissue engineering applications

The advent of three-dimensional (3D) bioprinting offers a feasible approach to construct complex structures for soft tissue regeneration. Carboxymethyl cellulose (CMC) has been emerging as a very promising biomaterial for 3D bioprinting. However, due to the inability to maintain the post-printed stability, CMC needs to be physically blended and/or chemically crosslinked with other polymers. In this context, this study presents the combination of CMC with xanthan gum (XG) and hyaluronic acid (HA) to formulate a multicomponent bioink, leveraging the printability of CMC and XG, as well as the cellular support properties of HA. The ionic crosslinking of printed constructs with iron(III) via the metal-ion coordination between ferric cations and carboxylate groups of the three polymers was introduced to induce improved mechanical strength and long-term stability. Moreover, immortalized human epidermal keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) encapsulated within iron-crosslinked printed hydrogels exhibited excellent cell viability (more than 95%) and preserved morphology. Overall, the presented study highlights that the combination of these three biopolymers and the ionic crosslinking with ferric ions is a valuable strategy to be considered for the development of new and advanced hydrogel-based bioinks for soft tissue engineering applications.

Thermo-assisted fabrication of a novel shape-memory hyaluronic acid sponge for non-compressible hemorrhage control

Hyaluronic acid (HA), a major component of skin extracellular matrix, provides an excellent framework for hemostatic design; however, there still lacks HA materials tailored with superior mechanical properties to address non-compressible hemorrhages. Here, we present a solvent-free thermal approach for constructing a shape-memory HA sponge for this application. Following facile thermal incubation around 130 °C, HA underwent cross-linking via esterification with poly(acrylic acid) within the sponge pre-shaped through a prior freeze-drying process. The resulting sponge system exhibited extensively interconnected macropores with a high fluid absorption capacity, excellent shape-memory property, and robust mechanical elasticity. When introduced to whole blood in vitro, the HA sponges demonstrated remarkable hemostatic properties, yielding a shorter coagulation time and lower blood clotting index compared to the commercial gelatin sponge (GS). Furthermore, in vivo hemostatic studies involving two non-compressible hemorrhage models (rat liver volume defect injury or femoral artery injury) achieved a significant reduction of approximately 64% (or 56%) and 73% (or 70%) in bleeding time and blood loss, respectively, which also outperformed GS. Additionally, comprehensive in vitro and in vivo evaluations suggested the good biocompatibility and biodegradability of HA sponges. This study highlights the substantial potential for utilizing the designed HA sponges in massive bleeding management.

A comprehensive exploration of hydrogel applications in multi-stage skin wound healing

Hydrogels, as an emerging biomaterial, have found extensive use in the healing of wounds due to their distinctive physicochemical structure and functional properties. Moreover, hydrogels can be made to match a range of therapeutic requirements for materials used in wound healing through specific functional modifications. This review provides a step-by-step explanation of the processes involved in cutaneous wound healing, including hemostasis, inflammation, proliferation, and reconstitution, along with an investigation of the factors that impact these processes. Furthermore, a thorough analysis is conducted on the various stages of the wound healing process at which functional hydrogels are implemented, including hemostasis, anti-infection measures, encouraging regeneration, scar reduction, and wound monitoring. Next, the latest progress of multifunctional hydrogels for wound healing and the methods to achieve these functions are discussed in depth and categorized for elucidation. Finally, perspectives and challenges associated with the clinical applications of multifunctional hydrogels are discussed.

Tranexamic acid-loaded catechol-modified hyaluronic acid/carboxymethyl chitosan double cross-linked porous gel micropowders for rapid hemostasis and wound healing

Acquiring rapid and effective hemostasis remains a critical clinical challenge. Current researches focus on concentrating blood components to speed up the hemostatic while ignore the effect of anti-fibrinolysis in promoting blood coagulation. Herein, we designed a novel tranexamic acid (TA)-loaded physicochemical double cross-linked multifunctional catechol-modified hyaluronic acid-dopamine/carboxymethyl chitosan porous gel micropowders (TA&Fe3+@HA-DA/CMCS PGMs) for rapid hemostasis and wound healing. TA&Fe3+@HA-DA/CMCS PGMs exhibited high water absorption rate (505.9 ± 62.1 %) and rapid hemostasis (79 ± 4 s) in vivo. Catechol groups, Fe3+ and the protonated amino groups of CMCS induced bacterial death. Moreover, TA&Fe3+@HA-DA/CMCS PGMs displayed sufficient adhesion to a variety of wet rat tissues. TA&Fe3+@HA-DA/CMCS PGMs on various bleeding wounds, including rat liver injury and tail severed models showed excellent hemostasis performance. The TA&Fe3+@HA-DA/CMCS PGMs could promote the healing of full-thickness skin wounds on the backs of rats. The advantages of TA&Fe3+@HA-DA/CMCS PGMs including rapid hemostasis, effective wound healing, good tissue adhesion, antibacterial properties and ease of use make it potentially valuable in clinical application.

Sulfated hyaluronic acid/collagen-based biomimetic hybrid nanofiber skin for diabetic wound healing: Development and preliminary evaluation

Diabetic foot ulcers (DFUs) are one of the most serious and devastating complication of diabetes, manifesting as foot ulcers and impaired wound healing in patients with diabetes mellitus. To solve this problem, sulfated hyaluronic acid (SHA)/collagen-based nanofibrous biomimetic skins was developed and used to promote the diabetic wound healing and skin remodeling. First, SHA was successfully synthetized using chemical sulfation and incorporated into collagen (COL) matrix for preparing the SHA/COL hybrid nanofiber skins. The polyurethane (PU) was added into those hybrid scaffolds to make up the insufficient mechanical properties of SHA/COL nanofibers, the morphology, surface properties and degradation rate of hybrid nanofibers, as well as cell responses upon the nanofibrous scaffolds were studied to evaluate their potential for skin reconstruction. The results demonstrated that the SHA/COL, SHA/HA/COL hybrid nanofiber skins were stimulatory of cell behaviors, including a high proliferation rate and maintaining normal phenotypes of specific cells. Notably, SHA/COL and SHA/HA/COL hybrid nanofibers exhibited a significantly accelerated wound healing and a high skin remodeling effect in diabetic mice compared with the control group. Overall, SHA/COL-based hybrid scaffolds are promising candidates as biomimetic hybrid nanofiber skin for accelerating diabetic wound healing.

Preparation of an injectable zinc-containing hydrogel with double dynamic bond and its potential application in the treatment of periodontitis

Periodontal tissue regeneration continues to face significant clinical challenges. Periodontitis leads to alveolar bone resorption and even tooth loss due to persistent microbial infection and persistent inflammatory response. As a promising topical drug delivery system, the application of hydrogels in the controlled release of periodontal bioactive drugs has aroused great interest. Therefore, the design and preparation of an injectable hydrogel with self-repairing properties for periodontitis treatment is still in great demand. In this study, polysaccharide-based self-healing hydrogels with antimicrobial osteogenic properties were developed. Zinc ions are introduced into a dynamic cross-linking network formed by dynamic Schiff bases between carboxymethyl chitosan and oxidized hyaluronic acid via coordination bonds. The OC-Zn hydrogels exhibited good tissue adhesion, good fatigue resistance, excellent self-healing ability, low cytotoxicity, good broad-spectrum antimicrobial activity, and osteogenic activity. Therefore, the designed hydrogels allow the development of drug delivery systems as a potential treatment for periodontitis.

Recent research advances in polysaccharide-based hemostatic materials: A review

Massive bleeding resulting from civil and martial accidents can often lead to shock or even death, highlighting the critical need for the development of rapid and efficient hemostatic materials. While various types of hemostatic materials are currently utilized in clinical practice, they often come with limitations such as poor biocompatibility, toxicity, and biodegradability. Polysaccharides, such as alginate (AG), chitosan (CS), cellulose, starch, hyaluronic acid (HA), and dextran, have exhibit excellent biocompatibility and in vivo biodegradability. Their degradation products are non-toxic to surrounding tissues and can be absorbed by the body. As a result, polysaccharides have been extensively utilized in the development of hemostatic materials and have gained significant attention in the field of in vivo hemostasis. This review offers an overview of the different forms, hemostatic mechanisms, and specific applications of polysaccharides. Additionally, it discusses the future opportunities and challenges associated with polysaccharide-based hemostats.

Advances of biological macromolecules hemostatic materials: A review

Achieving hemostasis is a necessary intervention to rapidly and effectively control bleeding. Conventional hemostatic materials currently used in clinical practice may aggravate the damage at the bleeding site due to factors such as poor adhesion and poor adaptation. Compared to most traditional hemostatic materials, polymer-based hemostatic materials have better biocompatibility and offer several advantages. They provide a more effective method of stopping bleeding and avoiding additional damage to the body in case of excessive blood loss. Various hemostatic materials with greater functionality have been developed in recent years for different organs using diverse design strategies. This article reviews the latest advances in the development of polymeric hemostatic materials. We introduce the coagulation cascade reaction after bleeding and then discuss the hemostatic mechanisms and advantages and disadvantages of various polymer materials, including natural, synthetic, and composite polymer hemostatic materials. We further focus on the design strategies, properties, and characterization of hemostatic materials, along with their applications in different organs. Finally, challenges and prospects for the application of hemostatic polymeric materials are summarized and discussed. We believe that this review can provide a reference for related research on hemostatic materials, contributing to the further development of polymer hemostatic materials.

Chitosan-based injectable hydrogel with multifunction for wound healing: A critical review

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Mussel inspired sequential protein delivery based on self-healing injectable nanocomposite hydrogel

Polysaccharide based self-healing and injectable hydrogels with reversible characteristics have widespread potential in protein drug delivery. However, it is a challenge to design the dynamic hydrogel for sequential release of protein drugs. Herein, we developed a novel mussel inspired sequential protein delivery dynamic polysaccharide hydrogel. The nanocomposite hydrogel can be fabricated through doping polydopamine nanoparticles (PDA NPs) into reversible covalent bond (imine bonds) crosslinked polymer networks of oxidized hyaluronic acid (OHA) and carboxymethyl chitosan (CEC), named PDA NPs@OHA-l-CEC. Besides multiple capabilities (i.e., injection, self-healing, and biodegradability), the nanocomposite hydrogel can achieve sustained and sequential protein delivery of vascular endothelial growth factor (VEGF) and bovine serum albumin (BSA). PDA NPs doped in hydrogel matrix serve dual roles, acting as secondary protein release structures and form dynamic non-covalent interactions (i.e., hydrogen bonds) with polysaccharides. Moreover, by adjusting the oxidation degree of OHA, the hydrogels with different crosslinking density could control overall protein release rate. Analysis of different release kinetic models revealed that Fickian diffusion drove rapid VEGF release, while the slower BSA release followed a Super Case II transport mechanism. The novel biocompatible system achieved sequential release of protein drugs has potentials in multi-stage synergistic drug deliver based on dynamic hydrogel.

Rapid self-healing carboxymethyl chitosan/hyaluronic acid hydrogels with injectable ability for drug delivery

In this study, the quaternized carboxymethyl chitosan (QCMCS), oxidized hyaluronic acid (OHA), 3,3'-dithiobis-(propionohydrazide) (DTP) were used as raw materials for the synthesis of hydrogels with excellent properties as carriers for drug release. The hydrogels were prepared by a simple "one-pot" method without external stimuli on the basis of interactions between formed dynamic covalent bonds (imine bonds, acylhydrazone bonds, disulfide bonds) and hydrogen bonds. The hydrogels had rapid self-healing properties, with a self-healing rate of 96 % after 30 min, as well as good pH responsiveness and excellent cytocompatibility (up to 98 % cell survival). The compressive stress of the hydrogels reached 423 kPa. Moreover, a representative drug (acetylsalicylic acid) demonstrated sustained release in the hydrogels (>72 h). The drug release behaviour was shown to be consistent with the Fick diffusion mechanism by kinetic modelling. Collectively, the findings demonstrate that the QCMCS + OHA + DTP injectable self-healing hydrogels are a potential material for the construction of pH-controlled drug delivery platforms.

Recent research advances on polysaccharide-, peptide-, and protein-based hemostatic materials: A review

Hemorrhage is a potentially life-threatening emergency that can occur at any time or place. Whether traumatic, congenital, surgical, disease-related, or drug-induced, bleeding can lead to severe complications or death. Therefore, the development of efficient hemostatic materials is critical. However, the results and prognosis demonstrated by clinical means of hemostasis do not reach expectations. With the development of technology, novel hemostatic materials have been developed from polysaccharides (chitosan, hyaluronic acid, alginate, cellulose, cyclodextrins, starch, dextran, and carrageenan), peptides (self-assembling peptides), and proteins (silk fibroin, collagen, gelatin, keratin, and thrombin). These new materials exhibit high hemostatic efficacy due to the enhancement or interaction of various hemostatic mechanisms. The main forms include adhesives, sealants, bandages, hemostatic powders, and hemostatic sponges. This article introduces the clotting process and principles of hemostatic methods and reviews the research on polysaccharide-, peptide-, and protein-based hemostatic materials in the last five years. The design ideas and hemostatic principles of polysaccharide-, peptide-, and protein-based hemostatic materials are mainly introduced. Finally, we summarize material designs, advantages, disadvantages, and challenges regarding hemostatic materials.

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

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

Functional hemostatic hydrogels: design based on procoagulant principles

Uncontrolled hemorrhage results in various complications and is currently the leading cause of death in the general population. Traditional hemostatic methods have drawbacks that may lead to ineffective hemostasis and even the risk of secondary injury. Therefore, there is an urgent need for more effective hemostatic techniques. Polymeric hemostatic materials, particularly hydrogels, are ideal due to their biocompatibility, flexibility, absorption, and versatility. Functional hemostatic hydrogels can enhance hemostasis by creating physical circumstances conducive to hemostasis or by directly interfering with the physiological processes of hemostasis. The procoagulant principles include increasing the concentration of localized hemostatic substances or establishing a physical barrier at the physical level and intervention in blood cells or the coagulation cascade at the physiological level. Moreover, synergistic hemostasis can combine these functions. However, some hydrogels are ineffective in promoting hemostasis or have a limited application scope. These defects have impeded the advancement of hemostatic hydrogels. To provide inspiration and resources for new designs, this review provides an overview of the procoagulant principles of hemostatic hydrogels. We also discuss the challenges in developing effective hemostatic hydrogels and provide viewpoints.

Development and biological evaluation of smart powder bandage for wound healing and dressing applications

Cutaneous wounds are one of the pressing concerns for healthcare systems globally. With large amounts of water, conventional hydrogels encounter obstacles in effectively delivering small molecules and peptides for wound healing. The surplus water content challenges the stability and sustained release of small molecules and peptides, diminishing their therapeutic efficacy. Our pioneering smart powder bandage, fabricated through freeze-drying, ensures a water content of <1 % during storage. Upon contact with wound exudate, it forms hydrogel layers, thereby optimizing the delivery of peptides. Tailored for thermosensitive peptides such as EGF, this strategy surmounts the limitations of conventional hydrogels, providing a robust platform for efficacious therapeutic delivery in wound healing applications. Developing multifunctional wound dressings with antibacterial, anti-inflammatory, hemostatic, and healing properties is essential to promote wound healing. Therefore, the current investigation reports the development of multifunctional EGF@Silnanom SPB with the above-mentioned properties to promote wound healing using silver nanomix (Silnanom) and bioactive epidermal growth factors (EGF) as active therapeutics. The characterization of smart powder bandage (SPB) revealed that Silnanom were homogeneously dispersed in the entangled polymer network. The multifunctional smart powder bandage exhibited high bacterial inhibition rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and rigorous hemocompatibility, cell compatibility, and in vivo studies also confirmed its biocompatibility. Furthermore, multifunctional EGF@Silnanom SPB effectively reduced pro-inflammatory markers, enhanced collagen deposition, promoted angiogenesis, and accelerated wound healing in a full-thickness mouse wound model through the sustained release of Silnanom and EGF. Additionally, the results of hemostasis analysis on the tail amputation mouse model confirmed the hemostasis properties of the EGF@Silnanom SPB. Overall, the multifunctional EGF@Silnanom SPB shows promising potential for skin wound repair, offering a potent and effective solution to the challenges posed by conventional wound dressings.

Recent advances in biopolymer-based hydrogels and their potential biomedical applications

Hydrogels are three-dimensional networks of polymer chains containing large amounts of water in their structure. Hydrogels have received significant attention in biomedical applications owing to their attractive physicochemical properties, including flexibility, softness, biodegradability, and biocompatibility. Different natural and synthetic polymers have been intensely explored in developing hydrogels for the desired applications. Biopolymers-based hydrogels have advantages over synthetic polymers regarding improved cellular activity and weak immune response. These properties can be further improved by grafting with other polymers or adding nanomaterials, and they structurally mimic the living tissue environments, which opens their broad applicability. The hydrogels can be physically or chemically cross-linked depending on the structure. The use of different biopolymers-based hydrogels in biomedical applications has been reviewed and discussed earlier. However, no report is still available to comprehensively introduce the synthesis, advantages, disadvantages, and biomedical applications of biopolymers-based hydrogels from the material point of view. Herein, we systematically overview different synthesis methods of hydrogels and provide a holistic approach to biopolymers-based hydrogels for biomedical applications, especially in bone regeneration, wound healing, drug delivery, bioimaging, and therapy. The current challenges and prospects of biopolymers-based hydrogels are highlighted rationally, giving an insight into the progress of these hydrogels and their practical applications.

Self-healing hydrogels based on biological macromolecules in wound healing: A review

The complete healing of skin wounds has been a challenge in clinical treatment. Self-healing hydrogels are special hydrogels formed by distinctive physicochemically reversible bonds, and they are considered promising biomaterials in the biomedical field owing to their inherently good drug-carrying capacity as well as self-healing and repair abilities. Moreover, natural polymeric materials have received considerable attention in skin tissue engineering owing to their low cytotoxicity, low immunogenicity, and excellent biodegradation rates. In this paper, we review recent advances in the design of self-healing hydrogels based on natural polymers for skin-wound healing applications. First, we outline a variety of natural polymers that can be used to construct self-healing hydrogel systems and highlight the advantages and disadvantages of different natural polymers. We then describe the principle of self-healing hydrogels in terms of two different crosslinking mechanisms-physical and chemical-and dissect their performance characteristics based on the practical needs of skin-trauma applications. Next, we outline the biological mechanisms involved in the healing of skin wounds and describe the current application strategies for self-healing hydrogels based on these mechanisms. Finally, we analyze and summarize the challenges and prospects of natural-material-based self-healing hydrogels for skin applications.

A multifunctional and self-adaptive double-layer hydrogel dressing based on chitosan for deep wound repair

Hydrogel wound dressing for irregular shape and deep wound repair is a research hotspot. Herein, a multifunctional and self-adaptive double-layer hydrogel was constructed, which was comprised of chitosan-based inner layer hydrogel and gellan gum-based outer layer hydrogel. Various properties of inner layer hydrogel were systematically investigated, including injectability, shape-adaptability, solid-liquid phase transition, biocompatibility, hemostasis, antibacterial performance and anti-inflammatory. Thanks to the phase-transition from solid to liquid at body temperature, inner layer hydrogel exhibited stronger adaptability to fill irregular and deep wounds, in which chitosan was liquefied and its therapeutic effect was maximized. Outer layer hydrogel was fabricated by calcium ions and gellan gum, whose certain mechanical strength could provide protection and a moister environment for wounds. Because of these characteristics, double-layer hydrogel markedly promoted skin tissue regeneration and wound closure and thereby possessed potential clinical application prospect as wound dressing for deep wounds.

Hydrogels dressings based on guar gum and chitosan: Inherent action against resistant bacteria and fast wound closure

Hydrogels made with depolymerized guar gum, oxidized with theoretical oxidation degrees of 20, 35 and 50 %, were obtained via Schiff's base reaction with N-succinyl chitosan. The materials obtained were subjected to characterization by FT-IR, rheology, swelling, degradation, and morphology. Additionally, their gelation time categorized all three hydrogels as injectable. The materials' swelling degrees in Phosphate-Buffered Saline (PBS) were in the range of 26-35 g of fluid/g gel and their pore size distribution was heterogeneous, with pores varying from 67 to 93 μm. All hydrogels degraded in PBS solution, but maintained around 40 % of their initial mass after 28 days, which was more than enough time for wound healing. The biomaterials were also flexible, self-repairing, adhesive and cytocompatible and presented intrinsic actions, regardless of the presence of additives or antibiotics, against gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and gram-negative bacteria (Escherichia coli). However, the most pronounced bactericidal effect was against resistant Staphylococcus aureus - MRSA. In vivo assays, performed with 50 % oxidized gum gel, demonstrated that this material exerted anti-inflammatory effects, accelerating the healing process and restoring tissues by approximately 99 % within 14 days. In conclusion, these hydrogels have unique characteristics, making them excellent candidates for wound-healing dressings.

CaO2-Cu2O micromotors accelerate infected wound healing through antibacterial functions, hemostasis, improved cell migration, and inflammatory regulation

During the wound tissue healing process, the relatively weak driving forces of tissue barriers and concentration gradients lead to a slow and inefficient penetration of bioactive substances into the wound area, consequently showing an impact on the effectiveness of deep wound healing. To overcome these challenges, we constructed biocompatible CaO2-Cu2O "micromotors". These micromotors reacted with the fluids at the wound site, releasing oxygen bubbles and propelling particles deep into the wound tissue. In vitro experimental results revealed that these micromotors not only exhibited antibacterial and hemostatic functions but also facilitated the migration of dermal fibroblasts and vascular endothelial cells, while modulating the inflammatory microenvironment. A methicillin-resistant Staphylococcus aureus infected full-thickness-wound model was created in rats, in which CaO2-Cu2O micromotors markedly expedited the wound healing process. Specifically, CaO2-Cu2O provided a sterile microenvironment for wounds and increased the amounts of M1-type macrophages during infection and inflammation. During the proliferation and remodeling stages, the amount of M1 macrophages gradually decreased, while the amount of M2 macrophages increased, and CaO2-Cu2O did not prolong the inflammatory period. Furthermore, the introduction of a regenerated silk fibroin (RSF) film on the wound surface successfully enhanced the therapeutic effects of CaO2-Cu2O against the infected wound. The combined application of oxygen-producing CaO2-Cu2O micromotors and a RSF film demonstrates significant therapeutic potential and emerges as a promising candidate for the treatment of infected wounds.

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.

Injectable multifunctional carboxymethyl chitosan/hyaluronic acid hydrogel for drug delivery systems

Injectable hydrogels with notable mechanical properties and self-healing ability are promising carriers for use as a drug delivery system. Here, adipic acid dihydrazide (ADH) and calcium ions (Ca2+) were introduced into quaternary ammonium carboxymethyl chitosan and aldehyde-modified hyaluronic acid hydrogels (QCS + OHA). The hydrogels were synthesized through the interaction of the Schiff bases (imine bonds, acylhydrazone bonds) and coordination bonds via a facile one-step approach. The gelation time (∼54 s) ensured excellent injectability. The QCS + OHA + ADH + Ca2+ hydrogel had notable mechanical properties (compressive stress up to 896.30 KPa), good self-healing ability (up to 94 %), good pH responsiveness, and excellent antibacterial properties. In addition, the QCS + OHA + ADH + Ca2+ hydrogel had a high drug loading capacity (121.3 mg/g) and sustained drug release behaviour (≥120 h). The results of cytotoxicity tests showed a high cell proliferation rate (up to 98 %) and good cytocompatibility. In summary, this work presents an injectable and self-healing pH-responsive hydrogel that can be used as a carrier for drug delivery systems.

Preparation and characterization of tannin-maltodextrin-polyvinyl alcohol hydrogel based on hydrogen bonding for wound healing

The development of multifunctional and low-cost hydrogel dressings with good mechanical properties, antibacterial activity, and nontoxicity is of great relevance in healthcare. This study aimed to prepare a series of hydrogels consisting of maltodextrin (MD), polyvinyl alcohol (PVA), and tannic acid (TA) through a freeze-thaw cycling technique. Micro-acid hydrogels with different mass ratios (0, 0.25, 0.5, and 1 wt%) were obtained by adjusting the TA content. Among all hydrogels, TA-MP2 hydrogels (with a TA content of 0.5 wt%) showed good physicochemical and mechanical properties. In addition, the biocompatibility of TA-MP2 hydrogels was confirmed by the high cell survival rate of NIH3T3 cells, which was over 90% after 24 h and 48 h of incubation. Additionally, TA-MP2 hydrogels showed multifunctional properties, including antibacterial and antioxidative effects. In vivo experiments showed that TA-MP2 hydrogel dressings significantly accelerated wound healing in a full-layer skin wound model. These findings indicated the potential of TA-MP2 hydrogel dressings in promoting wound healing.

Bletilla striata composite nanofibrous membranes prepared by emulsion electrospinning for enhanced healing of diabetic wounds

Diabetic wounds impose enormous distress and financial burden on patients, and finding effective dressings to manage wounds is critical. As a Chinese herbal medicine with a long history of Clinical application, Bletilla striata has significant medicinal effects in the therapy of various wounds. In this study, PLA and the pharmacodynamic substances of Bletilla striata were prepared into fibrous scaffolds by emulsion electrospinning technology for the management of diabetic wounds in mice. The results of scanning electron microscopy showed that the core-shell structure fibre was successfully obtained by emulsion electrospinning. The fibre membrane exhibited excellent water absorption capability and water vapor transmission rate, could inhibit the growth of Staphylococcus aureus and Pseudomonas aeruginosa, had good compatibility, and achieved excellent healing effect on diabetic wounds. Especially in the in vivo wound healing experiment, the wound healing rate of composite fibre membrane treatment reached 98.587 ± 2.149% in 16 days. This work demonstrated the good therapeutic effect of the developed fibrous membrane to diabetic wound, and this membrane could be potentially applied to chronic wound healing.

Animal tissue-derived biomaterials for promoting wound healing

The skin serves as the primary barrier between the human body and external environment, and is therefore susceptible to damage from various factors. In response to this challenge, animal tissue-derived biomaterials have emerged as promising candidates for wound healing due to their abundant sources, low side-effect profiles, exceptional bioactivity, biocompatibility, and unique extracellular matrix (ECM) mimicry. The evolution of modern engineering technology and therapies has allowed these animal tissue-derived biomaterials to be transformed into various forms and modified to possess the necessary properties for wound repair. This review provides an overview of the wound healing process and the factors that influence it. We then describe the extraction methods, important properties, and recent practical applications of various animal tissue-derived biomaterials. Our focus then shifts to the critical properties of these biomaterials in skin wound healing and their latest research developments. Finally, we critically examine the limitations and future prospects of biomaterials generated from animal tissues in this field.

Synthesis and characterization of Hyaluronic Acid (HA) modified polymeric composite for effective treatment of wound healing by transdermal drug delivery system (TDDS)

The present study aimed to fabricate a novel polymeric spongy composite to enhance skin regeneration composed of Nystatin (antifungal agent) and Silver Nanoparticles (AgNps). Different formulations (F1-F8) were developed & characterized by using various analytical techniques. AgNps synthesized by chemical reduction method showed spherical morphology 2 µm in size showed by SEM and XRD. A fine porous structure of gel embedded with AgNps having an amorphous structure with 10 % crystallinity due to AgNps was found. IR spectra revealed no chemical interaction between polymers and Nystatin. An increase in thermal stability of formulation was observed till 700 ℃ analyzed by Differential Scanning Calorimetry. Cytotoxic analysis on L929 mouse skin fibroblast cells showed a decrease in cell viability as Ag concentration increased (inactivating Fibroblast and keratinocytes) while 10 mg composition was found safest concentration (94%). Optimized formulation (F2) presented in-vitro drug release up to 90.59% ± 0.76 at pH 7.4, swelling studies (87.5% ± 0.57), water retention (26.60 ± 0.34), pH (5.31 ± 0.03). In the animal burn model, the group that received CHG/Ag/Nystatin healed the wound significantly (p < 0.05). These results suggested that optimized carrier can be used for other anti-fungal drugs facilitating the early healing of the wound.

Functional drug-delivery hydrogels for oral and maxillofacial wound healing

The repair process for oral and maxillofacial injuries involves hemostasis, inflammation, proliferation, and remodeling. Injury repair involves a variety of cells, including platelets, immune cells, fibroblasts, and various cytokines. Rapid and adequate healing of oral and maxillofacial trauma is a major concern to patients. Functional drug-delivery hydrogels play an active role in promoting wound healing and have shown unique advantages in wound dressings. Functional hydrogels promote wound healing through their adhesive, anti-inflammatory, antioxidant, antibacterial, hemostatic, angiogenic, and re-epithelialization-promoting properties, effectively sealing wounds and reducing inflammation. In addition, functional hydrogels can respond to changes in temperature, light, magnetic fields, pH, and reactive oxygen species to release drugs, enabling precise treatment. Furthermore, hydrogels can deliver various cargos that promote healing, including nucleic acids, cytokines, small-molecule drugs, stem cells, exosomes, and nanomaterials. Therefore, functional drug-delivery hydrogels have a positive impact on the healing of oral and maxillofacial injuries. This review describes the oral mucosal structure and healing process and summarizes the currently available responsive hydrogels used to promote wound healing.

Ultra-stretchable, tissue-adhesive, shape-adaptive, self-healing, on-demand removable hydrogel dressings with multiple functions for infected wound healing in regions of high mobility

Bacterial infection in the most mobile area usually leads to delayed healing and functional restriction, which has been a long-term challenge in clinic. Developing hydrogel-based dressings with mechanical flexibly, high adhesive and anti-bacterial properties, will contribute to the healing and therapeutic effects especially for this typical skin wound. In this work, composite hydrogel named PBOF through multi-reversible bonds between polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion demonstrated a 100 times ultra-stretch ability, 24 kPa of highly tissue-adhesive, rapid shape-adaptability within 2 min and self-healing feature within 40 s, was designed as the multifunctional wound dressing for the Staphylococcus aureus-infected skin wound in the mice nape model. Besides, this hydrogel dressing could be easily removed on-demand within 10 min by water. The rapid disassembly of this hydrogel is related to the formation of hydrogen bonds between polyvinyl alcohol and water. Moreover, the multifunctional properties of this hydrogel include strong anti-oxidative, anti-bacteria and hemostasis derived from oligomeric procyanidin and photothermal effect of ferric ion/polyphenol chelate. The killing ratio of the hydrogel on Staphylococcus aureus in infected skin wound reached 90.6% when exposed to 808 nm irradiation for 10 min. Simultaneously, reduced oxidative stress, suppressed inflammation, and promoted angiogenesis all together accelerated wound healing. Therefore, this well-designed multifunctional PBOF hydrogel holds great promise as skin wound dressing especially in the high mobile regions of the body. STATEMENT OF SIGNIFICANCE: An ultra-stretchable, highly tissue-adhesive, and rapidly shape-adaptive, self-healing and on-demand removable hydrogel based on multi-reversible bonds among polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion is designed as dressing material for infected wound healing in the movable nape. The rapid on-demand removal of the hydrogel relates to the formation of hydrogen bonds between polyvinyl alcohol and water. This hydrogel dressing shows strong antioxidant capacity, rapid hemostasis and photothermal antibacterial ability. This is derived from oligomeric procyanidin and thephotothermal effect of ferric ion/polyphenol chelate, which eliminates bacterial infection, reduces oxidative stress, regulates inflammation, promotes angiogenesis, and finally accelerates the infected wound healing in movable part.

Marine Biomaterials: Hyaluronan

The marine-derived hyaluronic acid and other natural biopolymers offer exciting possibilities in the field of biomaterials, providing sustainable and biocompatible alternatives to synthetic materials. Their unique properties and abundance in marine sources make them valuable resources for various biomedical and industrial applications. Due to high biocompatible features and participation in biological processes related to tissue healing, hyaluronic acid has become widely used in tissue engineering applications, especially in the wound healing process. The present review enlightens marine hyaluronan biomaterial providing its sources, extraction process, structures, chemical modifications, biological properties, and biocidal applications, especially for wound healing/dressing purposes. Meanwhile, we point out the future development of wound healing/dressing based on hyaluronan and its composites and potential challenges.

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

The prospective applications of chitosan-based hydrogels (CBHs), a category of biocompatible and biodegradable materials, in biomedical disciplines such as tissue engineering, wound healing, drug delivery, and biosensing have garnered great interest. The synthesis and characterization processes used to create CBHs play a significant role in determining their characteristics and effectiveness. The qualities of CBHs might be greatly influenced by tailoring the manufacturing method to get certain traits, including porosity, swelling, mechanical strength, and bioactivity. Additionally, characterization methods aid in gaining access to the microstructures and properties of CBHs. Herein, this review provides a comprehensive assessment of the state-of-the-art with a focus on the affiliation between particular properties and domains in biomedicine. Moreover, this review highlights the beneficial properties and wide application of stimuli-responsive CBHs. The main obstacles and prospects for the future of CBH development for biomedical applications are also covered in this review.

Rapidly degrading and mussel-inspired multifunctional carboxymethyl chitosan/montmorillonite hydrogel for wound hemostasis

The conventional method of using montmorillonite hemostatic materials affects the hemostatic effect due to easy dislodgement on the wound surface. In this paper, a multifunctional bio-hemostatic hydrogel (CODM) was prepared based on hydrogen bonding and Schiff base bonding using modified alginate, polyvinylpyrrolidone (PVP), and carboxymethyl chitosan. The amino group-modified montmorillonite was uniformly dispersed in the hydrogel by its amido bond formation with the carboxyl groups of carboxymethyl chitosan and oxidized alginate. The catechol group, -CHO, and PVP can form hydrogen bonds with the tissue surface to afford the firm tissue adhesion to afford the wound hemostatic. The addition of montmorillonite-NH₂ further improves the hemostatic ability, making it even better than commercial hemostatic materials. Moreover, the photothermal conversion ability (derived from the polydopamine) was synergized with the phenolic hydroxyl group, quinone group, and the protonated amino group to effectively kill the bacteria in vitro and in vivo. Based on its in vitro and in vivo biosafety and satisfactory degradation ratio anti-inflammatory, antibacterial, and hemostatic properties, the CODM hydrogel holds promising potential for emergency hemostasis and intelligent wound management.

Diversity of Bioinspired Hydrogels: From Structure to Applications

Hydrogels are three-dimensional networks with a variety of structures and functions that have a remarkable ability to absorb huge amounts of water or biological fluids. They can incorporate active compounds and release them in a controlled manner. Hydrogels can also be designed to be sensitive to external stimuli: temperature, pH, ionic strength, electrical or magnetic stimuli, specific molecules, etc. Alternative methods for the development of various hydrogels have been outlined in the literature over time. Some hydrogels are toxic and therefore are avoided when obtaining biomaterials, pharmaceuticals, or therapeutic products. Nature is a permanent source of inspiration for new structures and new functionalities of more and more competitive materials. Natural compounds present a series of physico-chemical and biological characteristics suitable for biomaterials, such as biocompatibility, antimicrobial properties, biodegradability, and nontoxicity. Thus, they can generate microenvironments comparable to the intracellular or extracellular matrices in the human body. This paper discusses the main advantages of the presence of biomolecules (polysaccharides, proteins, and polypeptides) in hydrogels. Structural aspects induced by natural compounds and their specific properties are emphasized. The most suitable applications will be highlighted, including drug delivery, self-healing materials for regenerative medicine, cell culture, wound dressings, 3D bioprinting, foods, etc.

Pentoxifylline/Chitosan Films on Wound Healing: In Vitro/In Vivo Evaluation

This study aimed to develop films of chitosan (CSF) associated with pentoxifylline (PTX) for healing cutaneous wounds. These films were prepared at two concentrations, F1 (2.0 mg/mL) and F2 (4.0 mg/mL), and the interactions between the materials, structural characteristics, in vitro release, and morphometric aspects of skin wounds in vivo were evaluated. The formation of the CSF film with acetic acid modifies the polymeric structure, and the PTX demonstrates interaction with the CSF, in a semi-crystalline structure, for all concentrations. The release for all films was proportional to the concentration, with two phases: a fast one of ≤2 h and a slow one of >2 h, releasing 82.72 and 88.46% of the drug after 72 h, being governed by the Fickian diffusion mechanism. The wounds of the mice demonstrate a reduction of up to 60% in the area on day 2 for F2 when compared to CSF, F1, and positive control, and this characteristic of faster healing speed for F2 continues until the ninth day with wound reduction of 85%, 82%, and 90% for CSF, F1, and F2, respectively. Therefore, the combination of CSF and PTX is effective in their formation and incorporation, demonstrating that a higher concentration of PTX accelerates skin-wound reduction.

Honokiol@PF127 crosslinked hyaluronate-based hydrogel for promoting wound healing by regulating macrophage polarization

Bacterial infection, oxidative stress and inflammation are the main obstacles in wound healing. Hydrogels with moist and inherent properties are beneficial to wound healing. Here, we fabricated a honokiol-laden micelle-crosslinked hyaluronate-based hydrogel by simply mixing honokiol-laden PF127-CHO micelles, 3,3'-dithiobis(propionohydrazide) grafted hyaluronic acid and silver ions. PF127 could not only effectively load hydrophobic small molecules but also be macromolecular crosslinker for preparing hydrogels. Hyaluronic acid plays an essential role in wound healing processes including regulating macrophage polarization towards M2 phenotype. The chemical dynamic acylhydrazone crosslinking and physical crosslinking among PF127-CHO micelles constructed hydrogel's networks, which endowed hydrogel with excellent self-healing properties. PF-HA-3 hydrogel also exhibited outstanding antioxidant and antibacterial capabilities. In a full-thickness skin defect model, this degradable and biocompatible hydrogel could promote wound healing by remodeling wound tissues, regulating M2 polarization and angiogenesis. In summary, this inherent multifunctional hydrogel will provide a promising strategy for designing bioactive compounds-based wound dressings.

Chitosan-Based Biomaterials for Tissue Regeneration

Chitosan is a chitin-derived biopolymer that has shown great potential for tissue regeneration and controlled drug delivery. It has numerous qualities that make it attractive for biomedical applications such as biocompatibility, low toxicity, broad-spectrum antimicrobial activity, and many others. Importantly, chitosan can be fabricated into a variety of structures including nanoparticles, scaffolds, hydrogels, and membranes, which can be tailored to deliver a desirable outcome. Composite chitosan-based biomaterials have been demonstrated to stimulate in vivo regeneration and the repair of various tissues and organs, including but not limited to, bone, cartilage, dental, skin, nerve, cardiac, and other tissues. Specifically, de novo tissue formation, resident stem cell differentiation, and extracellular matrix reconstruction were observed in multiple preclinical models of different tissue injuries upon treatment with chitosan-based formulations. Moreover, chitosan structures have been proven to be efficient carriers for medications, genes, and bioactive compounds since they can maintain the sustained release of these therapeutics. In this review, we discuss the most recently published applications of chitosan-based biomaterials for different tissue and organ regeneration as well as the delivery of various therapeutics.

Polysaccharide-Based Multifunctional Hydrogel Bio-Adhesives for Wound Healing: A Review

Wound healing is a long-term and complex biological process that involves multiple hemostasis, inflammation, proliferation, and remodeling stages. In order to realize comprehensive and systematic wound management, appropriate wound treatment bio-adhesives are urgently needed. Hydrogel bio-adhesives have excellent properties and show unique and remarkable advantages in the field of wound management. This review begins with a detailed description of the design criteria and functionalities of ideal hydrogel bio-adhesives for wound healing. Then, recent advances in polysaccharide-based multifunctional hydrogel bio-adhesives, which involve chitosan, hyaluronic acid, alginate, cellulose, dextran, konjac glucomannan, chondroitin sulfate, and other polysaccharides, are comprehensively discussed. Finally, the current challenges and future research directions of polysaccharide-based hydrogel bio-adhesives for wound healing are proposed to stimulate further exploration by researchers.

Chitosan-Based Hemostatic Hydrogels: The Concept, Mechanism, Application, and Prospects

The design of new hemostatic materials to mitigate uncontrolled bleeding in emergencies is challenging. Chitosan-based hemostatic hydrogels have frequently been used for hemostasis due to their unique biocompatibility, tunable mechanical properties, injectability, and ease of handling. Moreover, chitosan (CS) absorbs red blood cells and activates platelets to promote hemostasis. Benefiting from these desired properties, the hemostatic application of CS hydrogels is attracting ever-increasing research attention. This paper reviews the recent research progress of CS-based hemostatic hydrogels and their advantageous characteristics compared to traditional hemostatic materials. The effects of the hemostatic mechanism, effects of deacetylation degree, relative molecular mass, and chemical modification on the hemostatic performance of CS hydrogels are summarized. Meanwhile, some typical applications of CS hydrogels are introduced to provide references for the preparation of efficient hemostatic hydrogels. Finally, the future perspectives of CS-based hemostatic hydrogels are presented.

The Discovery and Development of Natural-Based Biomaterials with Demonstrated Wound Healing Properties: A Reliable Approach in Clinical Trials

Current research across the globe still focuses strongly on naturally derived biomaterials in various fields, particularly wound care. There is a need for more effective therapies that will address the physiological deficiencies underlying chronic wound treatment. The use of moist bioactive scaffolds has significantly increased healing rates compared to local and traditional treatments. However, failure to heal or prolonging the wound healing process results in increased financial and social stress imposed on health institutions, caregivers, patients, and their families. The urgent need to identify practical, safe, and cost-effective wound healing scaffolding from natural-based biomaterials that can be introduced into clinical practice is unequivocal. Naturally derived products have long been used in wound healing; however, clinical trial evaluations of these therapies are still in their infancy. Additionally, further well-designed clinical trials are necessary to confirm the efficacy and safety of natural-based biomaterials in treating wounds. Thus, the focus of this review is to describe the current insight, the latest discoveries in selected natural-based wound healing implant products, the possible action mechanisms, and an approach to clinical studies. We explore several tested products undergoing clinical trials as a novel approach to counteract the debilitating effects of impaired wound healing.