Hydrogels are crosslinked macromolecules (polymer networks) with segments of hydrophilic groups. Such polymer networks are able to swell as well as to shrink in liquid phases. This paper reports ...experimental results for the swelling behavior of a nonionic, synthetic hydrogel of
N-isopropyl acrylamide in partially miscible aqueous solutions of a single organic solvent (1-butanol and methyl isobutyl ketone) at 298
K. The experimental results are correlated applying a thermodynamic model, which combines an expression for the Gibbs energy of a liquid phase with an equation for the Helmholtz energy of an elastic network.
Gauze or bandages are commonly used to effectively control bleeding during trauma and surgery. However, conventional treatment methods can sometimes lead to secondary damages. In recent years, there ...has been increased interest in developing adhesive hemostatic hydrogels as a safer alternative for achieving hemostasis. Methylcellulose (MC) is a well-known thermo-sensitive polymer with excellent biocompatibility that is capable of forming a hydrogel through physical crosslinking owing to its inherent thermo-reversible properties. However, the poor mechanical properties of the MC hydrogel comprising a single crosslinked network (SN) limit its application as a hemostatic material. To address this issue, we incorporated a chitosan-gallol (CS-GA) conjugate, which has the ability to form chemical crosslinks through self-crosslinking reactions under specific pH conditions, into the MC hydrogel to reinforce the MC hydrogel network. The resulting MC/CS-GA hydrogel with a dual-crosslinked network (DN), involving both physical and chemical crosslinks, exhibited synergistic effects of the two types of crosslinks. Thus, compared with those of the SN hydrogel, the composite DN hydrogel exhibited significantly enhanced mechanical strength and tissue adhesive properties. Moreover, the DN hydrogel presented excellent biological activity in vitro. Additionally, in rat hepatic hemorrhage models, the DN hydrogel exhibited high hemostatic efficiency, showcasing its multifunctional capabilities.
The self-healing of this dynamic crosslinked hydrogel is mainly achieved by the formation of a dynamic B-O-B bond between the polymer chains.
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In this study, we have designed and ...synthesized a novel poly (4 - vinyl benzene boronic acid - co - N - vinyl pyrrolidone - co − 1 - vinyl − 3 - butylimidazolium bromide) hydrogel (VNV hydrogel) dressing with good self-healing properties and bactericidal activity. The gelation and self-healing of this hydrogel are mainly achieved by the formation of a dynamic B-O-B bond between the polymer chains, which is fractured by external forces and subsequently reformed. This self-healing mechanism is studied in detail through the molecular design of the hydrogel. The introduction of hydrophilic chemical groups can effectively improve the porous structures, water absorption and molecular migration. These properties have a positive effect on improving self-healing properties of dynamic crosslinked hydrogels. Furthermore, this VNV hydrogel dressing displays good antibacterial activity against E. coli, S. aureus, and C. albicans. The application of VNV hydrogel dressing on rat wound surface can effectively accelerate wound healing. These results indicate that this novel VNV hydrogel dressing with good self-healing properties and bactericidal activity has potential applications in wound dressings.
The flexible biodegradable polymer hydrogels have attracted increasing attention in the exploration of multifarious biomedical applications. However, conveniently achieving the synergistic ...characteristics of favorable mechanical performance, anti‐swelling behavior, antibacterial activity and conductivity into a biodegradable hydrogel remains a significant challenge. In this aspect, we report a facile one‐pot approach to prepare the multiple‐crosslinked PVA (PVA/PA‐Fe) hydrogels assisted by phytic acid (PA) and ferric trichloride. Firstly, PVA polymer chains and PA molecules form hydrogen bonds, meanwhile PA molecules interact with Fe3+ ions by ionic coordinations. Then, PVA polymer chains are crystallized by forming hydrogen bonds after cyclic freeze–thaw process. Based on the synergistic interactions of multiple hydrogen bonds and ionic coordinations in hydrogel system, PVA/PA‐Fe hydrogels possess favorable tensile strength (1222.72 kPa), toughness (1.82 MJ/m3) and anti‐swelling properties. Moreover, the introduction of PA and ferric trichloride successfully endows hydrogel with outstanding antimicrobial activity. Furthermore, the existence of H+ ions ionized by PA, Fe3+ and Cl− ions originating from ferric trichloride provides hydrogel with ionic conductivity (4.91 S/m) and strain responsiveness. Thus, the facile one‐pot preparation approach basing on the multiple‐crosslinked strategy would broaden the path for preparation of multifunctional hydrogels with promising biomedical applications, particularly smart flexible strain sensors.
The multiple‐crosslinked polyvinyl alcohol/phytic acid/ferric trichloride tough hydrogels (PVA/PA‐Fe hydrogels) with anti‐swelling property, antibacterial activity and conductivity were facilely and effectively constructed by facile one‐pot approach. The multifunctional PVA/PA‐Fe hydrogels have promising potential biomedical applications, particularly as medical flexible strain sensors.
Biomaterials capable of achieving effective sealing and hemostasis at moist wounds are in high demand in the clinical management of acute hemorrhage. Bletilla striata polysaccharide (BSP), a natural ...polysaccharide renowned for its hemostatic properties, holds promising applications in biomedical fields. In this study, a dual-dynamic-bonds crosslinked hydrogel was synthesized via a facile one-pot method utilizing poly(vinyl alcohol) (PVA)-borax as a matrix system, followed by the incorporation of BSP and tannic acid (TA). Chemical borate ester bonds formed around borax, coupled with multiple physical hydrogen bonds between BSP and other components, enhanced the mechanical properties and rapid self-healing capabilities. The catechol moieties in TA endowed the hydrogel with excellent adhesive strength of 30.2 kPa on the surface of wet tissues and facilitated easy removal without residue. Benefiting from the synergistic effect of TA and the preservation of the intrinsic properties of BSP, the hydrogel exhibited outstanding biocompatibility, antibacterial, and antioxidant properties. Moreover, it effectively halted acute bleeding within 31.3 s, resulting in blood loss of 15.6 % of that of the untreated group. As a superior hemostatic adhesive, the hydrogel in this study is poised to offer a novel solution for addressing future acute hemorrhage, wound healing, and other biomedical applications.
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•A novel Bletilla striata polysaccharide dual-dynamic-crosslinked hydrogel was developed.•The hydrogel was prepared by a facile one-pot method without chemical modification.•The hydrogel can firmly adhere to wet tissue surfaces.•The hydrogel can stop bleeding rapidly in mouse liver incision models.
For Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS), peeling off the PSS on its surface is a crucial step in improving its morphology and conductivity. Herein, a PVA-PP ...double-crosslinked hydrogel is developed using a chemical crosslinking method in situ based on PVA matrix. By utilizing dodecyl benzenesulfonic acid (DBSA), the PSS on the surface of PEDOT:PSS is partially peeled off and a distributed porous structure of PVA-PP-DBSA hydrogels is formed. The mechanical properties are greatly improved, with the tensile properties increasing from 90% to 580%. Additionally, the potential window is expanded from 0.8 V to 1.5 V. Furthermore, due to the formation of the pore structure and improved conductivity, a specific capacitance of up to 412 F g−1 (energy density of 131.4 Wh kg−1 and a power density of 1200 W kg−1) is achieved, demonstrating its excellent performance as a flexible and wearable power supply in the future.
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•A click-crosslinked hydrogel with in situ and rapid gel formation and good wound compliance was prepared for improving the therapeutic effect in wound infections.•The hydrogel has ...the ability of antibacterial, antioxidant and regulating macrophage polarization into M2-type macrophage in vitro and in vivo.•The hydrogel can accelerate infected wound healed and alleviate scar formation through facilitating neovascularization and collagen deposition by inhibiting bacterial infection, scavenging excess reactive free radicals, and regulating the immune microenvironment of the wound.
Bacterial infection, free radical accumulation and excessive inflammation are major factors leading to delayed wound healing. The rapid and effective elimination of wound bacteria and excess free radicals, and modulation of the wound immune microenvironment to accelerate infected wound healing is one of the pressing clinical issues. Common wound dressing or drugs are single-functional and risk of developing drug resistance. Therefore, multifunctional biomaterials with accelerated wound healing are urgently desired. Herein, we reported a click-crosslinked hydrogel with antibacterial, antioxidant and anti-inflammatory properties for infected wound repair. The hydrogel gelated from maleimide-based oxidized sodium alginate and sulfhydryl carboxymethyl chitosan based on “click” chemistry and Schiff base reaction possess short gelation time, good biocompatibility, broad-spectrum antibacterial activity, appropriate antioxidant and anti-inflammatory ability. Hydrogels effectively activate macrophage polarization toward the M2 phenotype and significantly promote the migration of repair-related cells (fibroblasts, epithelial cells and endothelial cells) and angiogenesis in vitro through paracrine mechanism. The in vivo results from a full-thickness infected wound model demonstrated that hydrogels can promote wound repair and regeneration by promoting angiogenesis and re-epithelialization through antibacterial, antioxidant and M2-type macrophage polarization. The bioactive hydrogels designed with antibacterial, antioxidant and M2 polarization promoting properties provide an efficient strategy for infected wound repair.
Self-healing hydrogels are attractive to extend material lifetime by rapid recovery from damage; the underlying healing mechanism regarding polymer diffusion are of broad research interest. However, ...intuitive and convenient characterization of polymer diffusion remains challenging due to the complex and dynamic features of hydrogels. Herein, we have constructed a dually-crosslinked hydrogel system to decouple complex factors for direct visualization of polymer diffusion and quantified study of healing dynamics. The successively formed dually-crosslinked hydrogel networks are designated for purposes of self-healing/visualization and tunable constraining effects (varied crosslinking density), respectively. As a result, we observed direct polymer diffusion across the crack interface and calculated the diffusion speed ranging from 0.51 to 0.04 μm/s depending on varied constraining degree. The corresponding self-healing performance is consistent with other conventional characterizations (e.g., dynamic mechanical properties, surface morphology changes). The above method has enabled facile visualization of dynamic healing processes with flexible adjustment of polymeric systems, which could inspire novel designs of high-performance self-healing materials.
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Hydrogels have been recognized for their versatile in regenerative medicine; however, their inadequate mechanical and osteogenic properties have limited their applicability in bone tissue engineering ...(BTE). Hence, we present a novel approach to address this issue by developing sulfated methacrylate hyaluronic acid hydrogels (SMeHA@CM) doped with alendronate (ALN), calcium ions (Ca2+), and magnesium ions (Mg2+). This hydrogel system incorporates sequential physical and chemical crosslinking to facilitate the treatment of bone defects. Physical crosslinks form between the SO32−, ALN, and Ca2+/Mg2+ ions, resulting in nanocluster crosslinking and complete filling of irregular bone defects. Subsequently, the methacrylate groups within the polymer chain undergo polymerization under ultraviolet light irradiation, forming the second stage of chemical crosslinking in the SMeHA@CM hydrogel. These chemical crosslinks contribute strong chemical bonds, enhancing biomechanical strength, and stable support for bone regeneration. The SMeHA@CM hydrogel exhibits remarkable osteogenic capacity, primarily attributed to the cooperative action of SO32− and Mg2+ ions, which promote the recruitment of bone marrow stem cells and angiogenesis. Furthermore, the sustained release of SO32−-ALN-Ca2+/Mg2+ nanoclusters from the hydrogel system offers additional benefits for bone regeneration. Moreover, both in-vitro and in-vivo assessments confirm the significant potential of the newly developed SMeHA@CM hydrogel for applications in BTE.
