Dynamic Schiff Base Research Articles

Neurovascularization inhibiting dual responsive hydrogel for alleviating the progression of osteoarthritis

Treating osteoarthritis (OA) associated pain is a challenge with the potential to significantly improve patients lives. Here, we report on a hydrogel for extracellular RNA scavenging and releasing bevacizumab to block neurovascularization at the osteochondral interface, thereby mitigating OA pain and disease progression. The hydrogel is formed by cross-linking aldehyde-phenylboronic acid-modified sodium alginate/polyethyleneimine-grafted protocatechuic acid (OSAP/PPCA) and bevacizumab sustained-release nanoparticles (BGN@Be), termed OSPPB. The dynamic Schiff base bonds and boronic ester bonds allow for injectability, self-healing, and pH/reactive oxygen species dual responsiveness. The OSPPB hydrogel can significantly inhibit angiogenesis and neurogenesis in vitro. In an in vivo OA model, intraarticular injection of OSPPB accelerates the healing process of condyles and alleviates chronic pain by inhibiting neurovascularization at the osteochondral interface. The injectable hydrogel represents a promising technique to treat OA and OA associated pain.

A multi-functional oxidative konjac glucomannan/ε-poly-l-lysine hydrogel with antibacterial, haemostatic, and chronic diabetic wound-treating properties.

A chronic diabetic wound, one of the most severe complications of diabetes, has a high incidence and causes great pain to patients, threatening their lives. In this paper, oxidative konjac glucomannan (OKGM) was reacted with ε-poly-l-lysine (EPL) through the dynamic Schiff's base reaction to make a multi-functional hydrogel. This hydrogel had excellent mechanical properties, injectability, self-healing ability, adhesivity and cytocompatibility. The outstanding haemostatic property was also expressed in rat liver incision, liver injury and tail truncation models. In addition, this hydrogel exhibited unique antibacterial ability against the Gram-positive Staphylococcus aureus (S. aureus), the Gram-negative Escherichia coli (E. coli) and the Gram-negative Pseudomonas aeruginosa (P. aeruginosa). It also promoted wound healing, enhanced angiogenesis and regulated macrophage polarisation in the whole-layer rat diabetic wound model. The multi-functional hydrogel is a dressing with huge potential and prospects in chronic diabetic wound healing.

NIR-responsive injectable nanocomposite hydrogels with enhanced angiogenesis for promoting full-thickness wound healing.

Angiogenesis plays a vital role in the treatment of full-thickness wounds. Deferoxamine (DFO) has been employed to promote neovascularization, however, smart drug delivery systems are needed to optimize its utilization. In this study, an injectable extracellular matrix (ECM)-mimicking hydrogel (HOG@P&D) was developed by leveraging the dynamic Schiff base and hydrogen bonds among a chitosan derivative (HACC), oxidized alginate (OSA), gelatin, and DFO-loaded polydopamine nanoparticles (P&D) for efficient wound healing. The incorporation of P&D enables HOG@P&D to respond to near-infrared (NIR) irradiation, converting laser energy into heat to trigger an on-demand, rapid release of DFO, thereby effectively enhancing angiogenesis. In vitro tube formation assays revealed that the number of meshes in the HOG@P&D group was fourfold higher than that of the control group. Additionally, HOG@P&D exhibited superior mechanical properties, tissue adhesion, and injectability, allowing it to cover wounds seamlessly. This hydrogel also demonstrated antibacterial and antioxidant properties, creating a conducive microenvironment for wound healing. In vivo studies further confirmed that HOG@P&D promoted angiogenesis and mitigated inflammation by upregulating angiogenic growth factor expression, thereby accelerating full-thickness wound healing. This nanocomposite hydrogel shows significant potential as a high-performance wound dressing.

Ultrafast self-healing zwitterionic hydrogels reinforced by carboxymethyl chitosan-oxidized hyaluronic acid and graphene oxide toward high-performance strain sensors

Inspired by the inherent recuperative ability of organisms in nature, researchers have dedicated significant efforts towards developing self-healing hydrogel sensors. Although the works on self-healing hydrogels have made great progress, achieving hydrogel sensors combining with rapid and efficient healing capability, excellent mechanical properties and high sensing sensitivity remains a challenging task. In this study, we proposed a novel approach for fabricating a self-healing conductive zwitterionic hydrogel sensor by adding carboxymethyl chitosan (CMCs) and oxidized hyaluronic acid (OHA) to induce dynamic Schiff base reaction, and nano-reinforced by adding with graphene oxide (GO) nanosheets. This zwitterionic hydrogel exhibited a high tensile strength of 133 kPa and elongation at break of 878 %. By leveraging various dynamic interactions within the system, the hydrogel exhibited ultra-fast and efficient healing property, achieving a self-healing efficiency of 98.9 % within just 15 min. The hydrogel demonstrated exceptional adhesion to diverse substrates especially to glass with a maximum adhesion strength reaching up to 53.7 kPa. The hydrogel exhibited a high gauge factor (GF) value of 23.2, which showed clear and stable monitoring and sensing capabilities across various human movements ranging from swallowing to bending knees. Notably, the hydrogel could also be employed as a Morse code transmitter and flexible tablet. The zwitterionic hydrogel demonstrates its great potential applications in the field of high-performance flexible sensors as well as human-computer interaction.

An effective drug-free hydrogel for accelerating the whole healing process of bacteria-infected wounds.

Wound healing is a dynamic and complex process involving hemostasis, inflammation, fibroblast proliferation, and tissue remodeling. This process is highly susceptible to bacterial infection, which often leads to impaired and delayed wound repair. While antibiotic therapy remains the primary clinical approach for treating bacteria-infected wounds, its widespread use poses a significant risk of developing bacterial resistance. Here, a novel drug-free hydrogel was fabricated using polysaccharides and humic acid (HU) to facilitate the healing of bacteria-infected wounds. Specifically, hyaluronic acid (HA) was modified via oxidation with sodium periodate, introducing aldehyde groups along its main chains. Pectin (PT) was grafted with amino groups on its side chains through an amidation reaction with ethylenediamine. HU, a natural organic compound with hemostatic, antioxidant, antibacterial, anti-inflammatory, and photothermal properties, was reduced using sodium borohydride to generate an increased number of phenolic hydroxyl and catechol groups. The resulting hydrogel, called HA-PT/HUOH, was prepared by integrating these three chemically modified biomaterials through dynamic Schiff base cross-linking and hydrogen bonding. The HA-PT/HUOH hydrogel showed excellent injectability, strong bioadhesiveness, rapid self-healing capabilities, and potent photothermal performance. Both in vitro and in vivo studies demonstrated that HA-PT/HUOH significantly accelerated the healing of bacteria-infected wounds by modulating the entire wound-healing process. This included enhancing hemostasis, bacteriostasis, antioxidation, anti-inflammatory responses, fibroblast proliferation, and tissue remodeling. In summary, this multifunctional drug-free hydrogel presents a highly promising solution as a wound dressing for clinical application.

An all-in-one “multifunctional hydrogel”: Through antibacterial, anti-inflammatory, and angiogenic to promoting MRSA-infected bone defect repair

Recently, in situ injectable hydrogels have emerged as a promising approach for bone defect healing. However, bone defect healing involves immunomodulation, angiogenesis, and osteogenic differentiation. Furthermore, the repair process is complicated by bacterial infections. Therefore, integrated treatment strategies are urgently needed to attain satisfactory therapeutic outcomes. This study presents an all-in-one multifunctional in situ injectable hydrogel (C/O/Sr/MA hydrogel) designed to repair MRSA-infected bone defects. Notably, carboxymethylated chlorogenic acid insect chitosan (ECCS-CA) exhibited an inhibitory effect on MRSA growth and formed complexes with Sr2+ through metal–ligand bonding. This interaction resulted in a notable reduction in inflammation, accompanied by a shift in macrophage polarization towards the M2 phenotype and enhanced vascularization and bone regeneration. Moreover, ECCS-CA was crosslinked with methacrylic anhydride-oxidized chondroitin sulfate (OCS-MA) via dynamic Schiff base. The cross-linking process enabled the C/O/Sr/MA hydrogel to effectively fill irregularly shaped bone defect sites upon injection and further improved its mechanical properties following UV curing. In rat models of MRSA-infected bone defects, the C/O/Sr/MA hydrogel demonstrated remarkable therapeutic efficacy, promoting bone regeneration, angiogenesis, and collagen deposition while inhibiting inflammatory responses. Overall, this all-in-one multifunctional hydrogel shows excellent promise for bone defect healing.

Vanillin-derived bio-based epoxy resins containing dual dynamic Schiff base and disulfide bonds with reprocessability and degradability

Incorporating reversible covalent bonds into the crosslinked matrix of bio-based epoxy resins can address the challenges of difficult degradation and sustainable development associated with petroleum-based epoxy resins. However, the dynamic capability conferred by a single dynamic chemical bond proves relatively insufficient in thermosetting polymers. Therefore, we propose a strategy to introduce proportionally adjustable dual dynamic covalent bonds in the bio-based epoxy resin system to leverage the advantages of different dynamic bonds and improve the dynamic properties of the resulting epoxy vitrimers in this study. First, a bio-based epoxy monomer (BVF-EP) derived from vanillin was prepared and cured with a diamine hardener (AFD). Subsequently, vanillin-derived epoxy vitrimers were prepared by varying the stoichiometric ratio of AFD to BVF-EP (R = 0.5, 1.0, and 1.5) without catalysts. Some of the vitrimers showed good thermal stability and excellent reprocessability and degradability. Notably, BVF-EP/AFD (R = 1.5) containing both dynamic reversible covalent bonds of S-S and C=N with the highest crosslink density, exhibited the highest thermal decomposition temperature, highest tensile modulus (7175 MPa), and the shortest stress relaxation time (6 s at 200 ℃). Simultaneously, BVF-EP/AFD (R = 1.5) demonstrated good multiple reprocessing capacity under a pressure of 5 MPa at 140 ℃. It can be completely degraded in two distinct mixed solutions (50 % DMF/50 % β-ME and 50 % 1 M HCl/50 % DMF), offering great potential in recovering high-value carbon fibers from its carbon fiber-reinforced composites. This work advances the development of bio-based epoxy resins with dual dynamic crosslinked networks, providing new insights for the degradation and reprocessing of thermoset polymers.

Multifunctional Nanocomposite Hydrogel with Enhanced Chemodynamic Therapy and Starvation Therapy for Inhibiting Postoperative Tumor Recurrence.

Surgical resection is the primary treatment for melanoma; however, preventing tumor recurrence after resection remains a significant clinical challenge. To address this, we developed a multifunctional nanocomposite hydrogel (H-CPG) composed of glucose oxidase (GOx)-coated CuS@PDA@GOx (CPG) nanoparticles, aminated hyaluronic acid (HA-ADH), and oxidized rhizomatous polysaccharides (OBSP), which are interconnected through hydrogen bonds and dynamic Schiff base linkages. In the acidic tumor micro-environment, the hydrogel releases GOx, catalyzing the production of hydrogen peroxide (H2O2), which enhances chemokinetic activity through a Cu2+-mediated Fenton-like reaction. This process generates hydroxyl radicals that intensify oxidative stress and promote macrophage polarization from the M2 to M1 phenotype. This polarization triggers the release of pro-inflammatory cytokines, thereby inhibiting tumor recurrence. Additionally, the hydrogel induces photothermal effects that help eradicate residual bacteria at the wound site. Overall, the H-CPG hydrogel offers a dual mechanism to prevent melanoma recurrence and reduce resistance to monotherapy, presenting a promising strategy for postoperative tumor management.

High mechanical, self-adhesive oxidized guar gum/chitosan hydrogel prepared at room temperature based on a nickel-urushiol catalytic system for wireless wearable sensors

Recently, sensors constructed on the basis of hydrogel are playing a major role in health detection such as motion detection and breathing monitoring. However, the common hydrogels have poor mechanical properties, insufficient adhesion and complex preparation processes, which hinder the further use of such sensors. In this paper, the conductive hydrogel (P(AA-UH)-OGG-CS/NiCl2) composed of acrylic acid (AA), oxidized guar gum (OGG) and chitosan (CS) was prepared at room temperature through the dynamic redox reaction of nickel chloride (NiCl2) and urushiol (UH). In detail, the reduction group (phenolic hydroxyl) of UH and Ni2+/Ni3+ pair form a semi-quinone/quinone redox dynamic cycle system, allowing the hydrogel to quickly gel at room temperature for 3 min. The catechol group in UH also promotes the hydrogel to have a superior adhesion strength of 25.23 kPa to pig skin and a strong repeated adhesion performance. In addition, the dynamic Schiff base bond created by the interaction of OGG and CS elevated the tensile stress of the hydrogel to 67.54 kPa. After the hydrogel is assembled into the sensor, it has high sensitivity and high stability to different strains, and has great application prospects in the field of actual human health monitoring.

Microenvironment‐Responsive Injectable Conductive Hydrogel for Spinal Cord Injury Repair

AbstractSpinal cord injury (SCI) represents a severe neurological condition often coupled with a drastic secondary inflammatory response, which further exacerbates the damage in most cases. Due to their unique electrical and mechanical compatibilities with the spinal cord, the utilization of conductive hydrogels through injection for SCI repair, particularly in scenarios involving non‐uniform and large gaps, has emerged as a promising approach. Herein, leveraging the acidic microenvironment characteristic of acute SCI sites, an injectable conductive hydrogel with pH‐responsive immunoregulation is engineered for SCI repair. Based on the dynamic Schiff base chemistry and covalent photo‐crosslinking, this composite hydrogel, composed of gelatin methacryloyl, oxidized dextran, and MoS2, exhibits adjustable mechanical and conductive properties, enabling a customized match with the natural spinal cord's attributes. Additionally, the incorporation of Wnt5a and its selective release in acidic conditions prompt the immediate suppression of inflammatory factors and enhances neural differentiation and regeneration. In the 2‐mm hemisection mouse SCI model, the optimized conductive hydrogel can effectively bridge the injury gap, establish nerve connections and signal, mitigate inflammatory response, and promoted recovery of mobility. This novel injectable conductive hydrogel system offers a promising advance in therapeutic materials for SCI repair.

Study of Low Temperature-Treated Aldolized Cellulose Nanocrystals for Enhancing Dye Separation and Self-Healing Properties of Graphene Oxide Membranes.

Graphene oxide (GO) membranes with a 2D layered structure and nanoscale channels have great application prospects for dye wastewater purification. In this paper, ethylenediamine (EDA) was grafted onto the surface of GO nanosheets at 70 °C and aldolized cellulose nanocrystals (ICNC) were introduced to form EDA-ICNC hydrogel structures between the GO nanosheets by Schiff base reaction. The interlayer structure of the membrane was determined by adjusting the amount of ICNC added and the degree of aldolization, and the EGOICNC-24 membrane with the best performance was prepared. The water flux is not only 12 times higher than that of GO membrane but also has a good separation ability for dye molecules with a molecular weight around 300. Following the EDA-ICNC-24 hydrogel cross-linking process, the tensile strength of the EGOICNC-24 membrane exhibited a 173% increase relative to that of the GO membrane. Additionally, the dye rejection rate reached 97.16% after 130 h of dye separation. When the surface of the membrane was damaged, it was self-healed by regulating the repair temperature and adding a very small amount of ICNC to undergo a dynamic Schiff base reaction and a synergistic effect of hydrogen bonding.

Preparation and recovery performance of modified cellulase with pH-sensitive separation properties

The efficient utilization of biomass resources holds significant importance for sustainable development in the energy, materials, and chemical industries. Therefore, it has garnered widespread attention. In this study, we have successfully achieved pH-sensitive separation and recycling of cellulase in an aqueous system. Firstly, the cellulase was modified by introducing a polyethylene glycol modifier with an aromatic aldehyde group. This modification altered the conformation of the cellulase and created a homogeneous-like system due to the hydrophilicity of the ethoxyl group in the modifier. As a result, the accessibility of the enzyme to the substrate was improved, which led to an increase in the enzyme activity of 116.12 %. The aromatic aldehyde group in the modifier and the primary amino group in the polyethyleneimine (PEI) formed a dynamic Schiff base covalent bond, which had pH-sensitive properties to ensure the completion of the recycling of the enzyme in the aqueous system. It was found that the molecular weight of PEI affected the recovery properties of the enzyme. Under the condition that the enzymatic activity was not damaged, the recovery rate of enzymatic activity increased as the molecular weight of the PEI increased. Particularly, when the molecular weight of PEI was 1800, the modified cellulase still retained an enzymatic activity recovery rate of 80 % after 5 cycles. This research provides a novel solution to improve the efficient hydrolysis of cellulose and the recovery of cellulase.

Injectable Salecan/hyaluronic acid-based hydrogels with antibacterial, rapid self-healing, pH-responsive and controllable drug release capability for infected wound repair

Designing materials for wound dressings with superior therapeutic benefits, self-healing and injectable characteristics is important in clinical practice. Herein, a new self-healing injectable hydrogel was prepared via thermal treatment and dynamic Schiff base reaction by mixing oxidized hyaluronic acid (OHA) and hydrazided Salecan (Sal-ADH). The versatility of the wound dressing was confirmed by studying the inherent rheological properties, high swelling rate, sustained-release behavior of the drug, pH/hyaluronidase-dependent biodegradation, in vitro antimicrobial as well as in vivo wound healing performance. The presence of the antimicrobial drug polyhexamethylene biguanide (PHMB) conferred good antimicrobial properties to the Sal-ADH/OHA/PHMB (SOP) hydrogel, which could effectively prevent wound infection (the width of the inhibition circle of SOP-0.20 hydrogel was 4.97 mm, 5.93 mm for Staphylococcus aureus and Escherichia coli, respectively). The findings suggested that SOP hydrogel exhibited remarkable self-healing and injectability properties, as well as excellent hemostasis and biocompatibility. In vivo experiments indicated that the application of SOP hydrogels would obviously accelerate wound healing and attenuate the inflammatory response while increasing collagen deposition and angiogenesis. Altogether, antibacterial SOP hydrogels with moderate mechanical properties, pH-responsive release, excellent injectability, exceptional self-healing ability and anti-inflammatory effects could expand potential applications of injectable hydrogels in the biomedical field.

Novel injectable adhesive hydrogel loaded with exosomes for holistic repair of hemophilic articular cartilage defect

Hemophilic articular cartilage damage presents a significant challenge for surgeons, characterized by recurrent intraarticular bleeding, a severe inflammatory microenvironment, and limited self-repair capability of cartilage tissue. Currently, there is a lack of tissue engineering-based integrated therapies that address both early hemostasis, anti-inflammation, and long-lasting chondrogenesis for hemophilic articular cartilage defects. Herein, we developed an adhesive hydrogel using oxidized chondroitin sulfate and gelatin, loaded with exosomes derived from bone marrow stem cells (BMSCs) (Hydrogel-Exos). This hydrogel demonstrated favorable injectability, self-healing, biocompatibility, biodegradability, swelling, frictional and mechanical properties, providing a comprehensive approach to treating hemophilic articular cartilage defects. The adhesive hydrogel, featuring dynamic Schiff base bonds and hydrogen bonds, exhibited excellent wet tissue adhesiveness and hemostatic properties. In a pig model, the hydrogel could be smoothly injected into the knee joint cartilage defect site and gelled in situ under fluid-irrigated arthroscopic conditions. Our in vitro and in vivo experiments confirmed that the sustained release of exosomes yielded anti-inflammatory effects by modulating macrophage M2 polarization through the NF-κB pathway. This immunoregulatory effect, coupled with the extracellular matrix components provided by the adhesive hydrogel, enhanced chondrogenesis, promoted the cartilage repair and joint function restoration after hemophilic articular cartilage defects. In conclusion, our results highlight the significant application potential of Hydrogel-Exos for early hemostasis, immunoregulation, and long-term chondrogenesis in hemophilic patients with cartilage injuries. This innovative approach is well-suited for application during arthroscopic procedures, offering a promising solution for addressing the complex challenges associated with hemophilic articular cartilage damage.

Advancing self‐healing soy protein hydrogel with dynamic Schiff base and metal‐ligand bonds for diabetic chronic wound recovery

AbstractTo address the unique challenges of diabetic wound healing, wound dressings, particularly multifunctional hydrogels have garnered considerable interest. For the first time, a novel environmentally friendly soy protein‐based hydrogel is developed to accelerate the healing of diabetic chronic wounds. Specifically, this hydrogel framework is in direct formation through the dynamic Schiff base between oxidized guar gum and epigallocatechin‐3‐gallate (EGCG)‐modified soy protein isolate. Meantime, the addition of Ag+ enhances the cross‐linking of the hydrogel network by forming metal‐ligand bonds with the catechol groups in EGCG. Interestingly, the stretchability (up to 380%), swelling, and rheology properties of the hydrogel can be controlled by fine‐tuning the density of metal‐ligand bonds, endowing them with a high potential for precise matching. Additionally, various dynamic bonds endow hydrogel with excellent self‐healing ability, adhesiveness, and injectability. This hydrogel also exhibits good antibacterial properties, biocompatibility, and cell migration capabilities. Both in vivo and in vitro experiments demonstrated the outstanding anti‐inflammatory capacity of the hydrogel and its ability to modulate macrophage polarization. Consequently, the hydrogel has proven effective in promoting wound healing in a diabetic full‐thickness wound model through enhanced angiogenesis and collagen deposition. This eco‐friendly plant protein hydrogel offers a sustainable solution for wound care and environmental protection.

Accelerated, injectable, self-healing, scarless wound dressings using rGO reinforced dextran/chitosan hydrogels incorporated with PDA-loaded asiaticoside

The process of wound healing is intricate and complex, necessitating the intricate coordination of various cell types and bioactive molecules. Despite significant advances, challenges persist in achieving accelerated healing and minimizing scar formation. Herein, a multifunctional hydrogel engineered via dynamic Schiff base crosslinking between oxidized dextran and quaternized chitosan, reinforced with reduced graphene oxide (rGO) is reported. The resulting OQG hydrogels demonstrated injectability to aid in conforming to irregular wound geometries, rapid self-healing to maintain structural integrity and adhesion for intimate integration with wound beds. Moreover, the developed hydrogels possessed antioxidant and antibacterial activities, mitigating inflammation and preventing infection. The incorporation of conductive rGO further facilitated the transmission of endogenous electrical signals, stimulating cell migration and tissue regeneration. In addition, the polydopamine-encapsulated asiaticoside (AC@PDA) nanoparticles were encapsulated in OQG hydrogels to reduce scar formation during in vivo evaluations. In vitro results confirmed the histocompatibility of the hydrogels to promote cell migration. The recovery of the full-thickness rat wounds revealed that these designed OQG hydrogels with the incorporation of AC@PDA nanoparticles could accelerate wound healing, reduce inflammation, facilitate angiogenesis, and minimize scarring when implemented. This multifunctional hydrogel system offers a promising strategy for enhanced wound management and scarless tissue regeneration, addressing the multifaceted challenges in wound care.

Oligolysine-based hydrogel dressing with antibacterial, anti-inflammatory, and tissue-adhesion activities for infected wound treatment

Fabricating injectable hydrogel with multiple functions and effective promotion of wound repair has a great prospect in treatment of bacterial infected wounds. Herein, a pH/reactive oxygen species (ROS) dual responsive injectable hydrogel (PVBDL-gel) was constructed, the PVBDL-gel was cross-linked by dynamic Schiff base bonds and borate ester bonds between poly(vanillin acrylate-co-3 acrylamide phenylboronic acid-co-N,N-dimethylacrylamide) (P(VA-co-AAPBA-co-DMA)), oligolysines and polyvinyl alcohol (PVA). The anti-inflammatory drug, dexamethasone sodium phosphate (DEX), was encapsulated in this hydrogel. The hydrogel exhibited excellent degradability, stable rheology and suitable tissue adhesion, more importantly, which showing pH/ROS responsive ability and controllable releasing of DEX. In vitro and in vivo experiment results showed that the PVBDL-gel with good biocompatibility and efficient anti-infection ability can effectively eradicate 99.9 % of pathogenic bacteria within 3 h and promote the repair and regeneration of bacterial infection wounds. This novel multifunctional injectable hydrogel has great application in the field of bacterial infection wound repair.

Dynamic Cross-Linking, Self-Healing, Antibacterial Hydrogel for Regenerating Irregular Cranial Bone Defects.

Given the widespread clinical demand, addressing irregular cranial bone defects poses a significant challenge following surgical procedures and traumatic events. In situ-formed injectable hydrogels are attractive for irregular bone defects due to their ease of administration and the ability to incorporate ceramics, ions, and proteins into the hydrogel. In this study, a multifunctional hydrogel composed of oxidized sodium alginate (OSA)-grafted dopamine (DO), carboxymethyl chitosan (CMCS), calcium ions (Ca2+), nanohydroxyapatite (nHA), and magnesium oxide (MgO) (DOCMCHM) was prepared to address irregular cranial bone defects via dynamic Schiff base and chelation reactions. DOCMCHM hydrogel exhibits strong adhesion to wet tissues, self-healing properties, and antibacterial characteristics. Biological evaluations indicate that DOCMCHM hydrogel has good biocompatibility, in vivo degradability, and the ability to promote cell proliferation. Importantly, DOCMCHM hydrogel, containing MgO, promotes the expression of osteogenic protein markers COL-1, OCN, and RUNX2, and stimulates the formation of new blood vessels by upregulating CD31. This study could provide meaningful insights into ion therapy for the repair of cranial bone defects.

Multibiofunctional Self-healing Adhesive Injectable Nanocomposite Polysaccharide Hydrogel.

Injectable hydrogels with good antimicrobial and antioxidant properties, self-healing characteristics, suitable mechanical properties, and therapeutic effects have great practical significance for developing treatments for pressing healthcare challenges. Herein, we have designed a novel, self-healing injectable hydrogel composite incorporating cross-linked biofunctional nanomaterials by mixing alginate aldehyde (Ox-Alg), quaternized chitosan (QCS), adipic acid dihydrazide (ADH), and copper oxide nanosheets surface functionalized with folic acid as the bioligand (F-CuO). Gelation was achieved under physiological conditions via the dynamic Schiff base cross-linking mechanism. The developed nanocomposite injectable hydrogel demonstrated the fast self-healing ability essential to bear deformation and outstanding antibacterial properties along with ROS scavenging ability. Furthermore, the optimized formulation of our F-CuO-embedded injectable hydrogel exhibited excellent cytocompatibility, blood compatibility, and in vitro wound healing performance. Taken together, the F-CuO nanosheet cross-linked injectable hydrogel composite presented herein offers a promising candidate biomaterial with multifunctional properties to develop solutions for addressing clinical challenges.

Ultra-fast cryogenic self-healing ionic hydrogel for flexible wearable bioelectronics

Anti-freezing and self-healing hydrogels have been developed extensively for their irreplaceable advantages in flexible bioelectronics. However, the self-healing performance of hydrogels is extremely inefficient or even disappears in cryogenic environments, resulting in device damage and economic loss. Here, we proposed a ultra-fast cryogenic self-healing ionic hydrogel (ASCL) based on aldehyded hyaluronic acid (AHA) with the synergistic effect of dynamic Schiff base bonds and diselenide bonds. With the addition of lithium chloride (LiCl), the ASCL hydrogel can be rapidly self-healed within 5 min at a cryogenic temperature of −20 °C. The mechanism of LiCl for enhancing the anti-freezing property of hydrogels was demonstrated by molecular dynamics simulations and a series of tests at cryogenic temperatures. ASCL hydrogels exhibited good flexibility and high electrical conductivity of 0.27 S/m at cryogenic temperatures. The assembled ASCL hydrogel strain sensors and pressure sensors enable sensitive detection of various human motions at −20 °C, which possess a gauge factor of 1.07 and a sensing sensitivity of 0.29 kPa−1, respectively. This work provides a new paradigm for developing flexible wearable hydrogel bioelectronics in extreme environments.