A Novel Wound Dressing Based on Ag/Graphene Polymer Hydrogel: Effectively Kill Bacteria and Accelerate Wound Healing

Avoiding wound infection and retaining an appropriate level of moisture around woundz are major challenges in wound care management. Therefore, designing hydrogels with desired antibacterial performance and good water‐maintaining ability is of particular significance to promote the development of wound dressing. Thus a series of hydrogels are prepared by crosslinking of Ag/graphene composites with acrylic acid and N,N′‐methylene bisacrylamide at different mass ratios. The antibacterial performance and accelerated wound‐healing ability of hydrogel are systematically evaluated with the aim of attaining a novel and effective wound dressing. The as‐prepared hydrogel with the optimal Ag to graphene mass ratio of 5:1 (Ag5G1) exhibits stronger antibacterial abilities than other hydrogels. Meanwhile, Ag5G1 hydrogel exhibits excellent biocompatibility, high swelling ratio, and good extensibility. More importantly, in vivo experiments indicate that Ag5G1 hydrogel can significantly accelerate the healing rate of artificial wounds in rats, and histological examination reveals that it helps to successfully reconstruct intact and thickened epidermis during 15 day of healing of impaired wounds. In one word, the present approach can shed new light on designing of antibacterial material like Ag/graphene composite hydrogel with promising applications in wound dressing.     

A Biomimetic Mussel‐Inspired ε‐Poly‐l‐lysine Hydrogel with Robust Tissue‐Anchor and Anti‐Infection Capacity

In situ hydrogels have attracted considerable attention in tissue engineering because of their minimal invasiveness and ability to match the irregular tissue defects. However, hydrous physiological environments and the high level of moisture in hydrogels severely hamper binding to the target tissue and easily cause wound infection, thereby limiting the effectiveness in wound care management. Thus, forming an intimate assembly of the hydrogel to the tissue and preventing wound infecting still remains a significant challenge. In this study, inspired by mussel adhesive protein, a biomimetic dopamine‐modified ε‐poly‐l ‐lysine‐polyethylene glycol‐based hydrogel (PPD hydrogel) wound dressing is developed in situ using horseradish peroxidase cross‐linking. The biomimetic catechol–Lys residue distribution in PPD polymer provides a catechol–Lys cooperation effect, which endows the PPD hydrogels with superior wet tissue adhesion properties. It is demonstrated that the PPD hydrogel can facilely and intimately integrate with biological tissue and exhibits superior capacity of in vivo hemostatic and accelerated wound repair. In addition, the hydrogels exhibit outstanding anti‐infection property because of the inherent antibacterial ability of ε‐poly‐l ‐lysine. These findings shed new light on the development of mussel‐inspired tissue‐anchored and antibacterial hydrogel materials serving as wound dressings.     

Conductive MXene Nanocomposite Organohydrogel for Flexible,Healable, Low‐Temperature Tolerant Strain Sensors

Conductive hydrogels are attracting tremendous interest in the field of flexible and wearable soft strain sensors because of their great potential in electronic skins, and personalized healthcare monitoring. However, conventional conductive hydrogels using pure water as the dispersion medium will inevitably freeze at subzero temperatures, resulting in the diminishment of their conductivity and mechanical properties; meanwhile, even at room temperature, such hydrogels suffer from the inevitable loss of water due to evaporation, which leads to a poor shelf‐life. Herein, an antifreezing, self‐healing, and conductive MXene nanocomposite organohydrogel (MNOH) is developed by immersing MXene nanocomposite hydrogel (MNH) in ethylene glycol (EG) solution to replace a portion of the water molecules. The MNH is prepared from the incorporation of the conductive MXene nanosheet networks into hydrogel polymer networks. The as‐prepared MNOH exhibits an outstanding antifreezing property (?40 °C), long‐lasting moisture retention (8 d), excellent self‐healing capability, and superior mechanical properties. Furthermore, this MNOH can be assembled as a wearable strain sensor to detect human biologic activities with a relatively broad strain range (up to 350% strain) and a high gauge factor of 44.85 under extremely low temperatures. This work paves the way for potential applications in electronic skins, human?machine interactions, and personalized healthcare monitoring.     

Conductive “Smart” Hybrid Hydrogels with PNIPAM and Nanostructured Conductive Polymers

Stimuli‐responsive hydrogels with decent electrical properties are a promising class of polymeric materials for a range of technological applications, such as electrical, electrochemical, and biomedical devices. In this paper, thermally responsive and conductive hybrid hydrogels are synthesized by in situ formation of continuous network of conductive polymer hydrogels crosslinked by phytic acid in poly(N‐isopropylacrylamide) matrix. The interpenetrating binary network structure provides the hybrid hydrogels with continuous transporting path for electrons, highly porous microstructure, strong interactions between two hydrogel networks, thus endowing the hybrid hydrogels with a unique combination of high electrical conductivity (up to 0.8 S m^?1), high thermoresponsive sensitivity (significant volume change within several seconds), and greatly enhanced mechanical properties. This work demonstrates that the architecture of the filling phase in the hydrogel matrix and design of hybrid hydrogel structure play an important role in determining the performance of the resulting hybrid material. The attractive performance of these hybrid hydrogels is further demonstrated by the developed switcher device which suggests potential applications in stimuli‐responsive electronic devices.     

Multifunctional Injectable Hydrogel Dressings for Effectively Accelerating Wound Healing: Enhancing Biomineralization Strategy

Bacterial infection can cause chronic nonhealing wounds, which may be a great threat to public health. It is highly desirable to develop an injectable wound dressing hydrogel with multifunctions including self-healing, remodeling, antibacterial, radical scavenging ability, and excellent photothermal properties to promote the regeneration of damaged tissues in clinical practice. In this work, dopamine-modified gelatin (Gel-DA) is employed for the first time as a biotemplate for enhancing the biomineralization ability of gelatin to synthesize dopamine-modified gelatin@Ag nanoparticles (Gel-DA@Ag NPs). Further, the prepared Gel-DA@Ag NPs with antioxidant activity and near-infrared (NIR) laser irradiation synergistic antibacterial behavior are fixed in the guar gum based hydrogels through the formation of borate/didiol bonds to possess remolding, injectable, and self-healing performance. In addition, the multifunctional hydrogels can completely cover the irregular wound shape to prevent secondary injury. More importantly, these hydrogel platforms under NIR can significantly accelerate wound healing with more skin appendages like hair follicles and blood vessels appearing. Therefore, it is expected that these hydrogels can serve as competitive multifunctional dressings in biomedical field, including bacteria-derived wound infection and other tissue repair related to reactive oxygen species overexpression.     

Graphene Oxide‐Templated Conductive and Redox‐Active Nanosheets Incorporated Hydrogels for Adhesive Bioelectronics

2D conductive nanosheets are central to electronic applications because of their large surface areas and excellent electronic properties. However, tuning the multifunctions and hydrophilicity of conductive nanosheets are still challenging. Herein, a green strategy is developed for fabricating conductive, redox‐active, water‐soluble nanosheets via the self‐assembly of poly(3,4‐ethylenedioxythiophene) (PEDOT) on the polydopamine‐reduced and sulfonated graphene oxide (PSGO) template. The conductivity and hydrophilicity of nanosheets are highly improved by PSGO. The nanosheets are redox active due to the abundant catechol groups and can be used as versatile nanofillers in developing conductive and adhesive hydrogels. The nanosheets create a mussel‐inspired redox environment inside the hydrogel networks and endow the hydrogel with long‐term and repeatable adhesiveness. This hydrogel is biocompatible and can be implanted for biosignals detection in vivo. This mussel‐inspired strategy for assembling 2D nanosheets can be adapted for producing diverse multifunctional nanomaterials, with various potential applications in bioelectronics.     

Injectable Polypeptide‐Protein Hydrogels for Promoting Infected Wound Healing

Protein is the key composition of all tissues, which has also been widely used in tissue engineering due to its superior biocompatibility and low immunogenicity. However, natural protein usually lacks active functions such as vascularization, osteo‐induction, and neural differentiation, which limits its further applications as a functional biomaterial. Here, based on the mimetic extracellular matrix feature of bovine serum albumin, injectable polypeptide‐protein hydrogels with vascularization and antibacterial abilities are constructed successfully via coordinative cross‐linking of sulfydryl groups with silver ions (Ag+) for the regeneration of infected wound. In this protein hydrogel system, (Ag+), acting as crosslinkers, can not only provide a sterile microenvironment and a strong and robust antibacterial ability but also introduce K₂(SL)₆K₂ (KK) polypeptide, which endows the hydrogel with vascularization behavior. Furthermore, the in vivo data show that the polypeptide‐protein hydrogel has a considerable collagen deposition and vascularization abilities in the early stage of wound healing, resulting in rapid new tissue regeneration featured with newly appeared hair follicles. Altogether, this newly developed multifunctional 3D polypeptide‐protein hydrogel with vascularization, antibacterial properties, and hair follicle promotion can be a promising approach in biomedical fields such as infected wound healing.     

A Novel Double‐Crosslinking‐Double‐Network Design for Injectable Hydrogels with Enhanced Tissue Adhesion and Antibacterial Capability for Wound Treatment

Most photocrosslinkable hydrogels have inadequacy in either mechanical performance or biodegradability. This issue is addressed by adopting a novel hydrogel design by introducing two different chitosan chains (catechol‐modified methacryloyl chitosan, CMC; methacryloyl chitosan, MC) via the simultaneous crosslinking of carbon–carbon double bonds and catechol‐Fe³⁺ chelation. This leads to an interpenetrating network of two chitosan chains with high crosslinking‐network density, which enhances mechanical performance including high compressive modulus and high ductility. The chitosan polymers not only endow the hydrogels with good biodegradability and biocompatibility, they also offer intrinsic antibacterial capability. The quinone groups formed by Fe³⁺ oxidation and protonated amino groups of chitosan polymer further enhance antibacterial property of the hydrogels. Serving as one of the two types of crosslinking mechanisms, the catechol‐Fe³⁺ chelation can covalently link with amino, thiol, and imidazole groups, which substantially enhance the hydrogel's adhesion to biological tissues. The hydrogel's adhesion to porcine skin shows a lap shear strength of 18.1 kPa, which is 6‐time that of the clinically established Fibrin Glue's adhesion. The hydrogel also has a good hemostatic performance due to the superior tissue adhesion as demonstrated with a hemorrhaging liver model. Furthermore, the hydrogel can remarkably promote healing of bacteria‐infected wound.     

Self‐Assembled Injectable Nanocomposite Hydrogels Stabilized by Bisphosphonate‐Magnesium (Mg2+) Coordination Regulates the Differentiation of Encapsulated Stem Cells via Dual Crosslinking

Nanocomposite hydrogels consist of a polymer matrix embedded with nanoparticles (NPs), which provide the hydrogels with unique bioactivities and mechanical properties. Incorporation of NPs via in situ precipitation in the polymer matrix further enhances these desirable hydrogel properties. However, the noncytocompatible pH, osmolality, and lengthy duration typically required for such in situ precipitation strategies preclude cell encapsulation in the resultant hydrogels. Bisphosphonate (BP) exhibits a variety of specific bioactivities and excellent binding affinity to multivalent cations such as magnesium ions (Mg²⁺). Here, the preparation of nanocomposite hydrogels via self‐assembly driven by bisphosphonate‐Mg²⁺ coordination is described. Upon mixing solutions of polymer bearing BPs, BP monomer (Ac‐BP), and Mg²⁺, this effective and dynamic coordination leads to the rapid self‐assembly of Ac‐BP‐Mg NPs which function as multivalent crosslinkers stabilize the resultant hydrogel structure at physiological pH. The obtained nanocomposite hydrogels are self‐healing and exhibit improved mechanical properties compared to hydrogels prepared by blending prefabricated NPs. Importantly, the hydrogels in this study allow the encapsulation of cells and subsequent injection without compromising the viability of seeded cells. Furthermore, the acrylate groups on the surface of Ac‐BP‐Mg NPs enable facile temporal control over the stiffness and crosslinking density of hydrogels via UV‐induced secondary crosslinking, and it is found that the delayed introduction of this secondary crosslinking enhances cell spreading and osteogenesis.     

Engineering Bioactive M2 Macrophage-Polarized Anti-Inflammatory,Antioxidant, and Antibacterial Scaffolds for Rapid Angiogenesis and Diabetic Wound Repair

Diabetic wound healing still faces great challenges due to the excessive inflammation, easy infection, and impaired angiogenesis in wound beds. The immunoregulation of macrophages polarization toward M2 phenotype that facilitates the transition from inflammation to proliferation phase has been proved to be an effective way to improve diabetic wound healing. Herein, an M2 phenotype-enabled anti-inflammatory, antioxidant, and antibacterial conductive hydrogel scaffolds (GDFE) for producing rapid angiogenesis and diabetic wound repair are reported. The GDFE scaffolds are fabricated facilely through the dynamic crosslinking between polypeptide and polydopamine and graphene oxide. The GDFE scaffolds possess thermosensitivity, self-healing behavior, injectability, broad-spectrum antibacterial activity, antioxidant and anti-inflammatory ability, and electronic conductivity. GDFE effectively activates the polarization of macrophages toward M2 phenotype and significantly promotes the proliferation of dermal fibroblasts, the migration, and in vitro angiogenesis of endothelial cells through paracrine mechanisms. The in vivo results from a full-thickness diabetic wound model demonstrate that GDFE can rapidly promote the diabetic wound repair and skin regeneration, through fast anti-inflammation and angiogenesis and M2 macrophage polarization. This study provides highly efficient strategy for treating diabetic wound repair through designing the M2 polarization-enabled anti-inflammatory, antioxidant, and antibacterial bioactive materials.     

Mussel‐Inspired Contact‐Active Antibacterial Hydrogel with High Cell Affinity,Toughness, and Recoverability

Antibacterial hydrogel has received extensive attention in soft tissue repair, especially preventing infections those associated with impaired wound healing. However, it is challenging in developing an inherent antibacterial hydrogel integrating with excellent cell affinity and superior mechanical properties. Inspired by the mussel adhesion chemistry, a contact‐active antibacterial hydrogel is proposed by copolymerization of methacrylamide dopamine (MADA) and 2‐(dimethylamino)ethyl methacrylate and forming an interpenetrated network with quaternized chitosan. The reactive catechol groups of MADA endow the hydrogel with contact intensified bactericidal activity, because it increases the exposure of bacterial cells to the positively charged groups of the hydrogel and strengthens the bactericidal effect. MADA also maintains the good adhesion of fibroblasts to the hydrogel. Moreover, the hybrid chemical and physical cross‐links inner the hydrogel network makes the hydrogel strong and tough with good recoverability. In vitro and in vivo tests demonstrate that this tough and contact‐active antibacterial hydrogel is a promising material to fulfill the dual functions of promoting tissue regeneration and preventing bacterial infection for wound‐healing applications.     

A Cooperative Copper Metal–Organic Framework‐Hydrogel System Improves Wound Healing in Diabetes

Chronic nonhealing wounds remain a major clinical challenge that would benefit from the development of advanced, regenerative dressings that promote wound closure within a clinically relevant time frame. The use of copper ions has shown promise in wound healing applications, possibly by promoting angiogenesis. However, reported treatments that use copper ions require multiple applications of copper salts or oxides to the wound bed, exposing the patient to potentially toxic levels of copper ions and resulting in variable outcomes. Herein the authors set out to assess whether copper metal organic framework nanoparticles (HKUST‐1 NPs) embedded within an antioxidant thermoresponsive citrate‐based hydrogel would decrease copper ion toxicity and accelerate wound healing in diabetic mice. HKUST‐1 and poly‐(polyethyleneglycol citrate‐co‐N‐isopropylacrylamide) (PPCN) are synthesized and characterized. HKUST‐1 NP stability in a protein solution with and without embedding them in PPCN hydrogel is determined. Copper ion release, cytotoxicity, apoptosis, and in vitro migration processes are measured. Wound closure rates and wound blood perfusion are assessed in vivo using the splinted excisional dermal wound diabetic mouse model. HKUST‐1 NPs disintegrated in protein solution while HKUST‐1 NPs embedded in PPCN (H‐HKUST‐1) are protected from degradation and copper ions are slowly released. Cytotoxicity and apoptosis due to copper ion release are significantly reduced while dermal cell migration in vitro and wound closure rates in vivo are significantly enhanced. In vivo, H‐HKUST‐1 induced angiogenesis, collagen deposition, and re‐epithelialization during wound healing in diabetic mice. These results suggest that a cooperatively stabilized, copper ion‐releasing H‐HKUST‐1 hydrogel is a promising innovative dressing for the treatment of chronic wounds.     

Injectable Self‐Healing Antibacterial Bioactive Polypeptide‐Based Hybrid Nanosystems for Efficiently Treating Multidrug Resistant Infection,Skin‐Tumor Therapy,and Enhancing Wound Healing

The surgical procedure in skin‐tumor therapy usually results in cutaneous defects, and multidrug‐resistant bacterial infection could cause chronic wounds. Here, for the first time, an injectable self‐healing antibacterial bioactive polypeptide‐based hybrid nanosystem is developed for treating multidrug resistant infection, skin‐tumor therapy, and wound healing. The multifunctional hydrogel is successfully prepared through incorporating monodispersed polydopamine functionalized bioactive glass nanoparticles (BGN@PDA) into an antibacterial F127‐ε‐Poly‐L‐lysine hydrogel. The nanocomposites hydrogel displays excellent self‐healing and injectable ability, as well as robust antibacterial activity, especially against multidrug‐resistant bacteria in vitro and in vivo. The nanocomposites hydrogel also demonstrates outstanding photothermal performance with (near‐infrared laser irradiation) NIR irradiation, which could effectively kill the tumor cell (>90%) and inhibit tumor growth (inhibition rate up to 94%) in a subcutaneous skin‐tumor model. In addition, the nanocomposites hydrogel effectively accelerates wound healing in vivo. These results suggest that the BGN‐based nanocomposite hydrogel is a promising candidate for skin‐tumor therapy, wound healing, and anti‐infection. This work may offer a facile strategy to prepare multifunctional bioactive hydrogels for simultaneous tumor therapy, tissue regeneration, and anti‐infection.     

Mussel‐Inspired Adhesive and Conductive Hydrogel with Long‐Lasting Moisture and Extreme Temperature Tolerance

Conductive hydrogels are a promising class of materials to design bioelectronics for new technological interfaces with human body, which are required to work for a long‐term or under extreme environment. Traditional hydrogels are limited in short‐term usage under room temperature, as it is difficult to retain water under cold or hot environment. Inspired by the antifreezing/antiheating behaviors from nature, and based on mussel chemistry, an adhesive and conductive hydrogel is developed with long‐lasting moisture lock‐in capability and extreme temperature tolerance, which is formed in a binary‐solvent system composed of water and glycerol. Polydopamine (PDA)‐decorated carbon nanotubes (CNTs) are incorporated into the hydrogel, which assign conductivity to the hydrogel and serve as nanoreinforcements to enhance the mechanical properties of the hydrogel. The catechol groups on PDA and viscous glycerol endow the hydrogel with high tissue adhesiveness. Particularly, the hydrogel is thermal tolerant to maintain all the properties under extreme wide tempreature spectrum (?20 or 60 °C) or stored for a long term. In summary, this mussel‐inspired hydrogel is a promising material for self‐adhesive bioelectronics to detect biosignals in cold or hot environments, and also as a dressing to protect skin from injuries related to frostbites or burns.     

An Injectable Self-Crosslinked Wholly Supramolecular Polyzwitterionic Hydrogel for Regulating Microenvironment to Boost Infected Diabetic Wound Healing

It is highly desirable yet significantly challenging to fabricate injectable, self-crosslinked, self-fused, and antifouling polyzwitterionic hydrogels, whose successful preparation will expand their application scope in biomedical fields. Herein, for the first time, a novel zwitterionic monomer, carboxybetaine urethane acrylate (CBUTA) is designed and synthesized with a urethane group and zwitterion on the same side chain. The strong inter-urethane H-bonds and zwitterionic dipole–dipole interactions of side chains contribute to self-crosslinked wholly supramolecular polyzwitterionic hydrogel that is directly formed from photoinitiated polymerization of CBUTA aqueous solution without adding any chemical crosslinkers. After being swollen in water, the polyCBUTA (PCBUTA) hydrogel is squeezed into small particles and freeze-dried to obtain hydrogel powder. The injectable and wholly zwitterionic supramolecular PCBUTA hydrogel can be easily reconstructed by mixing hydrogel powder with water due to the recombination of H-bonds of urethane groups and zwitterionic dipole–dipole interactions. The re-formed PCBUTA hydrogel exhibits an excellent self-fused and antifouling ability, and this injectable PCBUTA hydrogel, endowed with a microenvironment-regulated function, demonstrates excellent glucose consumption, antioxidation, antibacterial, and angiogenesis ability, thus accelerating the infected diabetic wound healing. Overall, this work provides a promising strategy to develop injectable and wholly zwitterionic hydrogels that will find broad biomedical applications.     

Zwitterionic Osmolyte‐Based Hydrogels with Antifreezing Property,High Conductivity,and Stable Flexibility at Subzero Temperature

Conductive hydrogels have emerged as fascinating materials applied in flexible electronics because of their integrated conductivity and mechanical flexibility. However, the large amounts of water in conductive hydrogels inevitably freeze at subzero temperature, causing a reduction of their ionic transport ability and elasticity. Herein, the bioinspired antifreezing agents—zwitterionic osmolytes (e.g., betaine, proline) are first proposed to prevent ammonium chloride‐containing Ca‐alginate/polyacrylamide hydrogels from freezing. With a facile one‐pot solvent displacement method, the zwitterionic osmolytes can displace the water molecules inside the hydrogels. Due to the excellent freeze tolerance of zwitterionic osmolytes, the resulting zwitterionic osmolyte‐based hydrogels exhibit outstanding ionic conductivity (up to ≈2.7 S m^?1) at ?40 °C, which exceeds the conductivities of most reported conductive hydrogels. Meanwhile, they present stable mechanical flexibility over a wide temperature range (?40 to 25 °C). More importantly, two types of the resulting hydrogel‐based flexible electronics, including a capacitive sensor and a resistive sensor, can maintain their response function at ?40 °C. This work offers a new solution to fabricate conductive hydrogels with antifreezing ability, which can broaden the working temperature range of flexible electronics.     

Black‐Phosphorus‐Incorporated Hydrogel as a Conductive and Biodegradable Platform for Enhancement of the Neural Differentiation of Mesenchymal Stem Cells

Conductive hydrogel scaffolds have important applications for electroactive tissue repairs. However, the development of conductive hydrogel scaffolds tends to incorporate nonbiodegradable conductive nanomaterials that will remain in the human body as foreign matters. Herein, a biodegradable conductive hybrid hydrogel is demonstrated based on the integration of black phosphorus (BP) nanosheets into the hydrogel matrix. To address the challenge of applying BP nanosheets in tissue engineering due to its intrinsic instability, a polydopamine (PDA) modification method is developed to improve the stability. Moreover, PDA modification also enhances interfacial bonding between pristine BP nanosheets and the hydrogel matrix. The incorporation of polydopamine‐modified black phosphorous (BP@PDA) nanosheets into the gelatin methacryloyl (GelMA) hydrogels significantly enhances the electrical conductivity of the hydrogels and improves the cell migration of mesenchymal stem cells (MSCs) within the 3D scaffolds. On the basis of the gene expression and protein level assessments, the BP@PDA‐incorporated GelMA scaffold can significantly promote the differentiation of MSCs into neural‐like cells under the synergistic electrical stimulation. This strategy of integrating biodegradable conductive BP nanomaterials within a biocompatible hydrogel provides a new insight into the design of biomaterials for broad applications in tissue engineering of electroactive tissues, such as neural, cardiac, and skeletal muscle tissues.     

Highly Stretchable,Elastic, and Ionic Conductive Hydrogel for Artificial Soft Electronics

High conductivity, large mechanical strength, and elongation are important parameters for soft electronic applications. However, it is difficult to find a material with balanced electronic and mechanical performance. Here, a simple method is developed to introduce ion‐rich pores into strong hydrogel matrix and fabricate a novel ionic conductive hydrogel with a high level of electronic and mechanical properties. The proposed ionic conductive hydrogel is achieved by physically cross‐linking the tough biocompatible polyvinyl alcohol (PVA) gel as the matrix and embedding hydroxypropyl cellulose (HPC) biopolymer fibers inside matrix followed by salt solution soaking. The wrinkle and dense structure induced by salting in PVA matrix provides large stress (1.3 MPa) and strain (975%). The well‐distributed porous structure as well as ion migration–facilitated ion‐rich environment generated by embedded HPC fibers dramatically enhances ionic conductivity (up to 3.4 S m^?1, at f = 1 MHz). The conductive hybrid hydrogel can work as an artificial nerve in a 3D printed robotic hand, allowing passing of stable and tunable electrical signals and full recovery under robotic hand finger movements. This natural rubber‐like ionic conductive hydrogel has a promising application in artificial flexible electronics.     

Physical Double‐Network Hydrogel Adhesives with Rapid Shape Adaptability,Fast Self‐Healing,Antioxidant and NIR/pH Stimulus‐Responsiveness for Multidrug‐Resistant Bacterial Infection and Removable Wound Dressing

Developing physical double‐network (DN) removable hydrogel adhesives with both high healing efficiency and photothermal antibacterial activities to cope with multidrug‐resistant bacterial infection, wound closure, and wound healing remains an ongoing challenge. An injectable physical DN self‐healing hydrogel adhesive under physiological conditions is designed to treat multidrug‐resistant bacteria infection and full‐thickness skin incision/defect repair. The hydrogel adhesive consists of catechol–Fe³⁺ coordination cross‐linked poly(glycerol sebacate)‐co‐poly(ethylene glycol)‐g‐catechol and quadruple hydrogen bonding cross‐linked ureido‐pyrimidinone modified gelatin. It possesses excellent anti‐oxidation, NIR/pH responsiveness, and shape adaptation. Additionally, the hydrogel presents rapid self‐healing, good tissue adhesion, degradability, photothermal antibacterial activity, and NIR irradiation and/or acidic solution washing‐assisted removability. In vivo experiments prove that the hydrogels have good hemostasis of skin trauma and high killing ratio for methicillin‐resistant staphylococcus aureus (MRSA) and achieve better wound closure and healing of skin incision than medical glue and surgical suture. In particular, they can significantly promote full‐thickness skin defect wound healing by regulating inflammation, accelerating collagen deposition, promoting granulation tissue formation, and vascularization. These on‐demand dissolvable and antioxidant physical double‐network hydrogel adhesives are excellent multifunctional dressings for treating in vivo MRSA infection, wound closure, and wound healing.     

Multifunctional DNA Hydrogels with Hydrocolloid-Cotton Structure for Regeneration of Diabetic Infectious Wounds

Currently, diabetic infectious wound treatments remain a significant challenge for regenerative medicine due to the unicity of clinical dressings, which lack systemic multifunctional wound dressings with high absorbability, customizable shape, rapid self-healing, guiding tissue regeneration, and restoring physiological functions. Here, a multifunctional DNA hydrogel is conveniently obtained through grafting DNA units and polyethyleneimine dynamic cross-linking and doped heating function black phosphorus quantum dots. The obtained DNA hydrogel features excellent exudate absorption performance, adjustable heating ability, mechanical behavior, self-healing ability, writability, tissue adhesion, and antibacterial properties. The incorporation of procyanidin B2 (OPC B2) endows the DNA hydrogels with renowned scavenging free radicals and antioxidant properties. Furthermore, the DNA hydrogel dressing can promote the transformation of macrophages from pro-inflammatory M1 into repairing M2 phenotype, keeping the wound in a stable remodeled state. Astonishingly, the DNA hydrogel dressing can activate neurons to transform into a repair state, accelerating skin nerve regeneration and angiogenesis. Beyond that, it can recruit myeloid cells to activate the adaptive immune response, enhancing the ability of DNA hydrogel dressing to promote tissue regeneration, thereby promoting hair follicle and hair regeneration. Therefore, this advanced collaborative strategy provides an effective method for cascade management of clinical guided tissue regeneration.