Search Results (321)

Self-healing hydrogels, a novel class of “smart” hydrogels, possess the ability to autonomously restore their network structure and mechanical properties following damage through the reconnection of a fractured three-dimensional network via reversible interactions. This characteristic enhances their safety and durability, exhibiting significant potential in biomedicine. The key determinants of self-healing hydrogels are their mechanical strength and healing efficiency. Ideally, these hydrogels exhibit both high mechanical strength and good healing efficiency. Nevertheless, an inverse relationship between the mechanical strength and self-healing efficiency of self-healing hydrogels typically exists. Thus, research is currently focused on the development of self-healing hydrogels that combine good biocompatibility, high mechanical strength, and good self-healing efficiency. This review focuses on the research progress that is being made regarding the mechanical properties and self-healing capabilities of self-healing hydrogels, where we aim to achieve a balance between self-healing performance and mechanical strength. We outline the evaluation methods for assessing self-healing performance, followed by providing a summary of recent advancements in the mechanical strength and self-healing efficiency of external-stimulus-triggered self-healing hydrogels and autonomous self-healing hydrogels. Finally, we address the challenges and prospects for the future development of self-healing hydrogels. Full article

Hydrogels are crosslinked polymer chains that form a three-dimensional network, widely used for wound dressing due to their ability to absorb significant amounts of fluid. This study aimed to develop a hydrogel patch for wound dressing with self-healing properties, particularly for joints and stretchable body parts, providing a physical barrier while maintaining an optimal environment for wound healing. Polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (Na CMC) were crosslinked with borax, which reacts with the active hydroxyl groups in both polymers to form a hydrogel. The patches were loaded with ciprofloxacin HCl (CIP), a broad-spectrum antibiotic used to prevent and treat various types of wound infections. Hydrogels were subjected to rheological, morphological, antimicrobial, self-healing, ex vivo release, swelling, cytotoxicity, wound healing, and stability studies. The hydrogels exhibited shear-thinning, thixotropic, and viscoelastic properties. Microscopic images of the CIP hydrogel patch showed a porous, crosslinked matrix. The antimicrobial activity of the patch revealed antibacterial effectiveness against five types of Gram-positive and Gram-negative bacteria, demonstrating a minimum inhibitory concentration of 0.05 μg/mL against E. coli. The swelling percentage was found to be 337.4 ± 12.7%. The cumulative CIP release percentage reached 103.7 ± 3.7% after 3 h, followed by zero-order release kinetics. The stability studies revealed that the crossover point shifted toward higher frequencies after 3 months of storage at room temperature, suggesting a relaxation in the hydrogel bonds. The cytotoxicity study revealed that the CIP hydrogel patch is non-cytotoxic. Additionally, the in vivo study demonstrated that the CIP hydrogel patch possesses wound-healing ability. Therefore, the CIP PVA/Na CMC/Borax patch could be used in wound dressing. Full article

Conductive hydrogels (CHs) have attracted significant attention in the fields of flexible electronics, human–machine interaction, and electronic skin (e-skin) due to their self-adhesiveness, environmental stability, and multi-stimuli responsiveness. However, integrating these diverse functionalities into a single conductive hydrogel system remains a challenge. In this study, polyvinyl alcohol (PVA) and polyacrylamide (PAM) were used as the dual-network matrix, lithium chloride and MXene were added, and a simple immersion strategy was adopted to synthesize a multifunctional MXene-based conductive hydrogel in a glycerol/water (1:1) binary solvent system. A subsequent investigation was then conducted on the hydrogel. The prepared PVA/PAM/LiCl/MXene hydrogel exhibits excellent tensile properties (~1700%), high electrical conductivity (1.6 S/m), and good self-healing ability. Furthermore, it possesses multimodal sensing performance, including humidity sensitivity (sensitivity of −1.09/% RH), temperature responsiveness (heating sensitivity of 2.2 and cooling sensitivity of 1.5), and fast pressure response/recovery times (220 ms/230 ms). In addition, the hydrogel has successfully achieved real-time monitoring of human joint movements (elbow and knee bending) and physiological signals (pulse, breathing), as well as enabled monitoring of spatial pressure distribution via a 3 × 3 sensor array. The performance and versatility of this hydrogel make it a promising candidate for next-generation flexible sensors, which can be applied in the fields of human health monitoring, electronic skin, and human–machine interaction. Full article

Postoperative adhesion remains a major clinical challenge, often leading to chronic pain, functional disorders, and recurrent surgeries. Herein, we developed a multifunctional gelatin–polyphenol hydrogel (GPP20) featuring rapid gelation (within 5 min), strong tissue adhesion (lasting > 24 h under physiological conditions), and intrinsic wound healing capacity to achieve integrated prevention of postoperative adhesion. GPP20 was fabricated via dynamic crosslinking between gelatin and tea polyphenol, endowing it with injectability, self-healing, biodegradability, and excellent mechanical properties (shear stress of 14.2 N). In vitro studies demonstrated that GPP20 exhibited effective ROS scavenging (82% ABTS scavenging capability), which protects cells against oxidative stress, while possessing excellent hemocompatibility and in vivo safety. Notably, GPP20 significantly reduced postoperative cecum–abdominal wall adhesions through both physical barrier effects and modulation of inflammation and collagen deposition, demonstrating a comprehensive integrated prevention strategy. Furthermore, in full-thickness wound models, GPP20 accelerated tissue regeneration (85% wound closure rate on day 10) by promoting macrophage polarization toward the M2 phenotype and stimulating angiogenesis, thereby enhancing collagen deposition and re-epithelialization. Collectively, these findings demonstrate that GPP20 integrates anti-adhesion efficacy with regenerative support, offering a facile and clinically translatable strategy for postoperative care and wound healing. Full article

Hydrogels with protein–polysaccharide combinations are widely used in the field of tissue engineering, as they can mimic the in vivo environments of native tissues, specifically the extracellular matrix (ECM). However, achieving stability and mechanical properties comparable to those of tissues by employing natural polymers remains a challenge due to their weak structural characteristics. In this work, we optimized the fabrication strategy of a hydrogel composite, comprising gelatin and sodium alginate (Gel-SA), by varying reaction parameters. Magnetite (Fe₃O₄) nanoparticles were incorporated to enhance the mechanical stability and structural integrity of the scaffold. The changes in hydrogel stiffness and viscoelastic properties due to variations in polymer mixing ratio, crosslinking time, and heating cycle, both before and after nanoparticle incorporation, were compared. FTIR spectra of crosslinked hydrogels confirmed physical interactions of Gel-SA, metal coordination bonds of alginate with Ca²⁺, and magnetite nanoparticles. Tensile and rheology tests confirmed that even at low magnetite concentration, the Gel-SA-Fe₃O₄ hydrogel exhibits mechanical properties comparable to soft tissues. This work has demonstrated enhanced resilience of magnetite-incorporated Gel-SA hydrogels during the heating cycle, compared to Gel-SA gel, as thermal stability is a significant concern for hydrogels containing gelatin. The interactions of thermoreversible gelatin, anionic alginate, and nanoparticles result in dynamic hydrogels, facilitating their use as viscoelastic acellular matrices. Full article

Hydrogels have garnered significant attention as multifunctional materials in next-generation rechargeable batteries due to their high ionic conductivity, mechanical flexibility, and structural tunability. This review presents a comprehensive overview of hydrogel types—including natural, synthetic, composite, carbon-based, conductive polymer, and MOF hydrogels—and their synthesis methods, such as chemical crosslinking, self-assembly, and irradiation-based techniques. Characterization tools like SEM, XRD, and FTIR are discussed to evaluate their microstructure and performance. In rechargeable batteries systems, hydrogels enhance ionic transport and mechanical stability, particularly in lithium-ion, sodium-ion, zinc-ion, magnesium-ion, and aluminum-ion batteries. Despite their advantages, hydrogels face challenges such as limited mechanical strength, reduced stability under extreme conditions, and scalability issues. Current research focuses on advanced formulations, self-healing mechanisms, and sustainable materials to overcome these limitations. This review highlights the pivotal role of hydrogels in shaping the future of flexible, high-performance, and environmentally friendly secondary batteries. Full article

Hydrogels are rapidly emerging as a versatile and promising platform for advancing energy storage and conversion technologies. Their intrinsic properties—such as high water content, excellent ionic conductivity, and inherent mechanical flexibility—position them as key materials for a wide range of applications, including supercapacitors, flexible membranes, and components in fuel cells and solar cells. Despite significant progress, challenges remain in enhancing their mechanical durability, developing scalable fabrication methods, and ensuring environmental sustainability. Recent breakthroughs in composite hydrogel systems, innovative manufacturing techniques such as 3D printing, and self-healing strategies are driving substantial improvements in device performance and operational lifespan. Emphasizing the importance of interdisciplinary approaches and innovative material design, this review highlights the transformative potential of hydrogel-based energy systems in shaping a sustainable and flexible energy future. The advancements discussed herein have promising implications for the development of high-performance, environmentally friendly, and adaptable energy devices capable of meeting the demands of next-generation applications. Full article

Polymer gel-based triboelectric nanogenerators (TENGs) have emerged as versatile platforms for self-powered sensing due to their inherent softness, stretchability, and tunable conductivity. This review comprehensively explores the roles of polymer gels in TENG architecture, including their function as triboelectric layers, electrodes, and conductive matrices. We analyze four operational modes—vertical contact-separation, lateral-sliding, single-electrode, and freestanding configurations—alongside key performance metrics. Recent studies have reported output voltages of up to 545 V, short-circuit currents of 48.7 μA, and power densities exceeding 120 mW/m², demonstrating the high efficiency of gel-based TENGs. Gel materials are classified by network structure (single-, double-, and multi-network), matrix composition (hydrogels, aerogels, and ionic gels), and dielectric medium. Strategies to enhance conductivity using ionic salts, conductive polymers, and nanomaterials are discussed in relation to triboelectric output and sensing sensitivity. Morphological features such as surface roughness, porosity, and micro/nano-patterning are examined for their impact on charge generation. Application-focused sections detail the integration of gel-based TENGs in health monitoring (e.g., sweat, glucose, respiratory, and tremor sensing), environmental sensing (e.g., humidity, fire, marine, and gas detection), and tactile interfaces (e.g., e-skin and wearable electronics). Finally, we address current challenges, including mechanical durability, dehydration, and system integration, and outline future directions involving self-healing gels, hybrid architectures, and AI-assisted sensing. This review expands the subject area by synthesizing recent advances and offering a strategic roadmap for developing intelligent, sustainable, and multifunctional TENG-based sensing technologies. Full article

The scalable fabrication of hydrogels with high toughness and low hysteresis is critically hindered by oxygen inhibition, which typically produces brittle, highly crosslinked (HC) networks. This study presents an oxygen-tolerant photoinduced electron transfer–reversible addition–fragmentation chain transfer (PET-RAFT) strategy for synthesizing highly entangled (HE) polyacrylamide hydrogels under open-vessel conditions. By optimizing the water-to-monomer ratio (W = 3.9) and introducing lithium chloride (LiCl) for spatial confinement, we achieved a fundamental shift in mechanical performance. The optimized HE hydrogel exhibited a fracture energy of 1.39 MJ/m³ and a fracture strain of ~900%, starkly contrasting the brittle failure of the HC control (W = 20, C = 10⁻²) at ~50% strain. This represents an order-of-magnitude improvement in deformability. Furthermore, the incorporation of 15 wt% LiCl amplified the HE hydrogel’s fracture energy to 2.17 MJ/m³ while maintaining its low hysteresis. This method enables the rapid, scalable production of robust, transparent thin films that exhibit dual passive cooling via radiative emission (>89% emissivity) and evaporation, rapid self-healing, and reliable strain sensing at temperatures as low as −20 °C. The synergy of entanglement design and confinement engineering establishes a versatile platform for manufacturing multifunctional hydrogels that vastly outperform their crosslink-dominated predecessors. Full article

Immunoregulation is an emerging treatment strategy to promote wound healing by modulating the local immune system at the wound site. In this study, an extracellular matrix biomimetic and polysaccharide-based hydrogel was engineered to regulate the wound immune environment through Michael-type addition between maleimidyl pullulan and chitosan modified with hydroxyproline. The proposed hydrogel exhibited favorable injectable and self-healing properties, which facilitated the full coverage of irregularly shaped wounds. A natural polyphenol, epigallocatechin-3-gallate (EGCG), was incorporated into hydrogels, which thereby exhibited excellent biocompatibility, good reactive oxygen species (ROS) scavenging ability, anti-inflammatory activity, and antibacterial properties against S. aureus and E. coli. Furthermore, evaluations of a full-thickness skin defect mice model showed that the hydrogel with EGCG effectively alleviated the inflammatory response by reducing pro-inflammatory cellular infiltration and down-regulating the inflammatory cytokine TNF-α, while up-regulating anti-inflammatory cytokine IL-10. Notably, a faster wound healing rate was also achieved by the better promotion effect of the hydrogel on increasing the formation of re-epithelialization, granulation tissue generation, collagen deposition, and angiogenesis. Therefore, our immunoregulatory strategy showed great potential in the design of biomaterials for wound management. Full article

Janus hydrogels have attracted significant attention in materials science and biomedicine owing to their anisotropic dual-faced architecture. Unlike conventional homogeneous hydrogels, these heterogeneous systems exhibit structural and functional asymmetry, endowing them with remarkable adaptability to dynamic environmental stimuli. Their inherent biocompatibility, biodegradability, and unique “adhesion–antiadhesion” duality have demonstrated exceptional potential in biomedical applications ranging from advanced wound healing and internal tissue adhesion prevention to cardiac tissue regeneration. Furthermore, “hydrophilic–hydrophobic” Janus configurations, synergistically integrated with tunable conductivity and stimuli-responsiveness, showcase the great potential in emerging domains, including wearable biosensing, high-efficiency desalination, and humidity regulation systems. This review systematically examines contemporary synthesis strategies for Janus hydrogels using various technologies, including layer-by-layer, self-assembly, and one-pot methods. We elucidate the properties and applications of Janus hydrogels in biomedicine, environmental engineering, and soft robotics, and we emphasize recent developments in this field while projecting future trajectories and challenges. Full article

This study presents an innovative iontophoretic delivery system for glycolic acid (GA) based on polysaccharide microbeads embedded within an electrolyte hydrogel. The mi-crobeads, fabricated using a peristaltic pump, exhibited a uniform morphology with an average diameter of 1078 ± 140.38 μm and were successfully integrated into a hydrogel matrix (thickness: 4542.55 ± 337.24 μm). Comprehensive physicochemical characterization (FT-IR, XRD, SEM) confirmed effective component integration. The hydrogel demonstrated optimal mechanical properties with a tensile strength of 0.02 ± 0.003 MPa and reliable adhesion to various substrates, while maintaining excellent self-healing capabili-ties—post-repair conductivity remained sufficient to power an LED indicator. The material demonstrated favorable conductivity under various storage conditions while maintaining non-cytotoxic properties. Notably, microbead incorporation preserved electrochemical performance, as demonstrated by stable behavior in cyclic voltammetry using an Ag/AgCl reference system. Iontophoretic testing revealed significantly enhanced glycolic acid delivery at −1.0 V com-pared to passive diffusion. The system, combining PVA, PAA, alginate, [Bmim]BF₄, and E. prolifera polysaccharides with gellan gum, shows strong potential for advanced cosmetic dermatology applications requiring precise active ingredient delivery. Full article

Diabetes is emerging as a significant health and societal concern globally, impacting both young and old populations. In individuals with diabetic foot ulcers (DFUs), the wound healing process is hindered due to abnormal glucose metabolism and chronic inflammation. Minor injuries, blisters, or pressure sores can develop into chronic ulcers, which, if left untreated, may lead to serious infections, tissue necrosis, and eventual amputation. Current management techniques include debridement, wound dressing, oxygen therapy, antibiotic therapy, topical application of antibiotics, and surgical skin grafting, which are used to manage diabetic wounds and foot ulcers. This review focuses on a hydrogel-based strategy for phase-wise targeting of DFUs, addressing sequential stages of diabetic wound healing: hemostasis, infection, inflammation, and proliferative/remodeling phases. Hydrogels have emerged as a promising wound care solution due to their unique properties in providing a suitable wound-healing microenvironment. We explore natural polymers, including hyaluronic acid, chitosan, cellulose derivatives, and synthetic polymers such as poly (ethylene glycol), poly (acrylic acid), poly (2-hydroxyethyl methacrylate, and poly (acrylamide), emphasizing their role in hydrogel fabrication to manage DFU through phase-dependent strategies. Recent innovations, including self-healing hydrogels, stimuli-responsive hydrogels, nanocomposite hydrogels, bioactive hydrogels, and 3D-printed hydrogels, demonstrate enhanced therapeutic potential, improving patient outcomes. This review further discusses the applicability of various hydrogels to each phase of wound healing in DFU treatment, highlighting their potential to advance diabetic wound care through targeted, phase-specific interventions. Full article

Hydrogels are water-rich polymeric networks mimicking the body’s extracellular matrix, making them highly biocompatible and ideal for precision medicine. Their “tunable” and “smart” properties enable the precise adjustment of mechanical, chemical, and physical characteristics, allowing responses to specific stimuli such as pH or temperature. These versatile materials offer significant advantages over traditional drug delivery by facilitating targeted, localized, and on-demand therapies. Applications range from diagnostics and wound healing to tissue engineering and, notably, cancer therapy, where they deliver anti-cancer agents directly to tumors, minimizing systemic toxicity. Hydrogels’ design involves careful material selection and crosslinking techniques, which dictate properties like swelling, degradation, and porosity—all crucial for their effectiveness. The development of self-healing, tough, and bio-functional hydrogels represents a significant step forward, promising advanced biomaterials that can actively sense, react to, and engage in complex biological processes for a tailored therapeutic approach. Beyond their mechanical resilience and adaptability, these hydrogels open avenues for next-generation therapies, such as dynamic wound dressings that adapt to healing stages, injectable scaffolds that remodel with growing tissue, or smart drug delivery systems that respond to real-time biochemical cues. Full article

Conductive hydrogels hold great promise for biomedical and electronic applications. However, their practical use is often limited by poor self-healing capability, which can affect long-term stability and durability. To address this, we developed alginate/polyacrylamide-based conductive hydrogels incorporating FeCl₃ and AlCl₃, named CH-Fe and CH-Al, respectively. We systematically studied the influence of metal cations on the hydrogels’ mechanical and electrical properties. CH-Al showed the most optimized performance, with a 329% increase in tensile strength and a 323% improvement in conductivity compared to the blank hydrogel. Additionally, CH-Al demonstrated excellent self-healing ability, with nearly 100% recovery after damage. The introduction of Al³⁺ improved conductivity by forming dynamic electron-conductive pathways through interactions with the polymer network. The self-healing behavior arises from reversible metal–ligand coordination bonds, which enable rapid recovery of the hydrogel’s structure after mechanical disruption. This study successfully developed a conductive hydrogel that combines high electrical conductivity, robust mechanical strength, and an intrinsic self-healing ability, offering significant potential for applications in bioelectronic devices, flexible sensors, and implantable medical technologies. Full article