Skin-inspired gelatin-based flexible bio-electronic hydrogel for wound healing promotion and motion sensing

Electrospinning/3D printing drug-loaded antibacterial polycaprolactone nanofiber/sodium alginate-gelatin hydrogel bilayer scaffold for skin wound repair

Skin injuries and defects, as a common clinical issue, still cannot be perfectly repaired at present, particularly large-scale and infected skin defects. Therefore, in this work, a drug-loaded bilayer skin scaffold was developed for repairing full-thickness skin defects. Briefly, amoxicillin (AMX) was loaded on polycaprolactone (PCL) nanofiber via electrospinning to form the antibacterial nanofiber membrane (PCL-AMX) as the outer layer of scaffold to mimic epidermis. To maintain wound wettability and promote wound healing, external human epidermal growth factor (rhEGF) was loaded in sodium alginate-gelatin to form the hydrogel structure (SG-rhEGF) via 3D printing as inner layer of scaffold to mimic dermis. AMX and rhEGF were successfully loaded into the scaffold. The scaffold exhibited excellent physicochemical properties, with elongation at break and tensile modulus were 102.09 ± 6.74% and 206.83 ± 32.10 kPa, respectively; the outer layer was hydrophobic (WCA was 112.09 ± 4.67°), while the inner layer was hydrophilic (WCA was 48.87 ± 5.52°). Meanwhile, the scaffold showed excellent drug release and antibacterial characteristics. In vitro and in vivo studies indicated that the fabricated scaffold could enhance cell adhesion and proliferation, and promote skin wound healing, with favorable biocompatibility and great potential for skin regeneration and clinical application.

Photocrosslinked carboxymethylcellulose-based hydrogels: Synthesis, characterization for curcumin delivery and wound healing

Skin could protect our body and regenerate itself to against dysfunctional and disfiguring scars when faced with external injury. As wound dressings, hydrogels are biocompatible, hydrophilic and have a 3D structure similar to the extracellular matrix (ECM). In particular, hydrogels with drug-releasing capabilities are in acute wound healing. In this paper, photocrosslinked hydrogels served as wound dressing based on sodium carboxymethylcellulose (CMC) were prepared to promote wound healing. Photocrosslinked hydrogels were prepared by grafting lysine and allyl glycidyl ether (AGE) onto CMC and encapsulating curcumin (Cur). The synthesized hydrogels had the unique 3D porous structure with a swelling ratio up to 1300 % in aqueous solution. The drug release ratios of the hydrogels were 20.8 % in acid environment, and 14.4 % in alkaline environment. Notably, the hydrogels showed good biocompatibility and antibacterial properties and also exhibited the ability to accelerate the process of skin wound healing while prevent inflammation and scar formation when applied to a mouse skin wound model. As a result, the prepared hydrogels Gel-CLA@Cur showed great potential in wound healing.

A Multifunctional Tissue-Engineering Hydrogel Aimed to Regulate Bacterial Ferroptosis-Like Death and Overcoming Infection Toward Bone Remodeling

Infection is the most common complication after orthopedic surgery and can result in prolonged ailments such as chronic wounds, enlarged bone defects, and osteomyelitis. Iron, which is essential for bacterial metabolism and immune cell functions, is extremely important. Bacteria harness iron from nearby cells to promote biofilm formation, ensuring their survival. Iron deficiency within the infection microenvironment (IME) consequently hampers macrophage function, enabling further dissemination of the infection and hindering macrophage polarization to the M2 phenotype. Therefore, a novel approach is proposed to regulate macrophage polarization, aiming to restore the inflammatory immune environment. A composite hydrogel derived from natural polymers is developed to address infections and manage iron metabolism in macrophages. This IME-responsive hydrogel, named FCL-ECMH, is synthesized by encapsulating vermiculite functional core layers within a decellularized extracellular matrix hydrogel. It is noteworthy that FCL-ECMH can produce reactive oxygen species within the IME. Supplementary photothermal treatment enhances bacterial iron uptake, leading to ferroptosis-like death. This process also rejuvenates the iron-enriched macrophages around the IME, thereby enhancing their antibacterial and tissue repair functions. In vivo experiments confirmed the antibacterial and repair-promoting capabilities of FCL-ECMH, indicating its potential for clinical applications.

What Exactly Can Bionic Strategies Achieve for Flexible Sensors?

Flexible sensors have attracted great attention in the field of wearable electronic devices due to their deformability, lightness, and versatility. However, property improvement remains a key challenge. Fortunately, natural organisms exhibit many unique response mechanisms to various stimuli, and the corresponding structures and compositions provide advanced design ideas for the development of flexible sensors. Therefore, this Review highlights recent advances in sensing performance and functional characteristics of flexible sensors from the perspective of bionics for the first time. First, the "twins" of bionics and flexible sensors are introduced. Second, the enhancements in electrical and mechanical performance through bionic strategies are summarized according to the prototypes of humans, plants, and animals. Third, the functional characteristics of bionic strategies for flexible sensors are discussed in detail, including self-healing, color-changing, tangential force, strain redistribution, and interfacial resistance. Finally, we summarize the challenges and development trends of bioinspired flexible sensors. This Review aims to deepen the understanding of bionic strategies and provide innovative ideas and references for the design and manufacture of next-generation flexible sensors.

Designing a Naturally Inspired Conductive Copolymer to Engineer Wearable Bioadhesives for Sensing Applications

The design of adhesive and conductive soft hydrogels using biopolymers with tunable mechanical properties has received significant interest in the field of wearable sensors for detecting human motions. These hydrogels are primarily fabricated through the modification of biopolymers to introduce cross-linking sites, the conjugation of adhesive components, and the incorporation of conductive materials into the hydrogel network. The development of a multifunctional copolymer that integrates adhesive and conductive properties within a single polymer chain with suitable cross-linking sites eliminates the need for biopolymer modification and the addition of extra conductive and adhesive components. In this study, we synthesized a copolymer based on poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride-co-dopamine methacrylamide) (p(METAC-DMA)) using a controlled radical polymerization, allowing for the efficient conjugation of both adhesive and conductive units within a single polymer chain. Subsequently, our multifunctional hydrogel named Gel-MD was fabricated by mixing the p(METAC-DMA) copolymer with non-modified gelatin in which cross-linking took place in an oxidative environment. We confirmed the biocompatibility of the Gel-MD hydrogel through in vitro studies using NIH 3T3 cells as well as in vivo subcutaneous implantation in rats. Furthermore, the Gel-MD hydrogel was effective and sensitive in detecting various human motions, making it a promising wearable sensor for health monitoring and diagnosis.

3D-Bioprinted Skin Tissues for Improving Wound Healing: Current Status and Perspective

Advancements in tissue engineering enable the fabrication of complex and functional tissues or organs. In particular, bioprinting enables controlled and accurate deposition of cells, biomaterials, and growth factors to create complex 3D skin constructs specific to a particular individual. Despite these advancements, challenges such as vascularization, long-term stability, and regulatory considerations hinder the clinical translation of bioprinted skin constructs. This chapter focuses on such approaches using advanced biomaterials and bioprinting techniques to overcome the current barriers in wound-healing studies. Moreover, it addresses current obstacles in wound-healing studies, highlighting the need for continued research and innovation to overcome these barriers and facilitate the practical utilization of bioprinted skin constructs in clinical settings.

Platelet-Derived Growth Factor Nanocapsules with Tunable Controlled Release for Chronic Wound Healing

Chronic wounds have emerged as an increasingly critical clinical challenge over the past few decades, due to their increasing incidence and socioeconomic burdens. Platelet-derived growth factor (PDGF) plays a pivotal role in regulating processes such as fibroblast migration, proliferation, and vascular formation during the wound healing process. The delivery of PDGF offers great potential for expediting the healing of chronic wounds. However, the clinical effectiveness of PDGF in chronic wound healing is significantly hampered by its inability to maintain a stable concentration at the wound site over an extended period. In this study, a controlled PDGF delivery system based on nanocapsules is proposed. In this system, PDGF is encapsulated within a degradable polymer shell. The release rate of PDGF from these nanocapsules can be precisely adjusted by controlling the ratios of two crosslinkers with different degradation rates within the shells. As demonstrated in a diabetic wound model, improved therapeutic outcomes with PDGF nanocapsules (nPDGF) treatment are observed. This research introduces a novel PDGF delivery platform that holds promise for enhancing the effectiveness of chronic wound healing.

Enhanced wound regeneration by PGS/PLA fiber dressing containing platelet-rich plasma: an in vitro study

Novel wound dressings with therapeutic effects are being continually designed to improve the wound healing process. In this study, the structural, chemical, physical, and biological properties of an electrospun poly glycerol sebacate/poly lactide acid/platelet-rich plasma (PGS/PLA-PRP) nanofibers were evaluated to determine its impacts on in vitro wound healing. Results revealed desirable cell viability in the Fibroblast (L929) and macrophage (RAW-264.7) cell lines as well as human umbilical vein endothelial cells (HUVEC). Cell migration was evident in the scratch assay (L929 cell line) so that it promoted scratch contraction to accelerate in vitro wound healing. Moreover, addition of PRP to the fiber structure led to enhanced collagen deposition (~ 2 times) in comparison with PGS/PLA scaffolds. While by addition PRP to PGS/PLA fibers not only decreased the expression levels of pro-inflammatory cytokines (IL-6 and TNF-α) in RAW-264.7 cells but also led to significantly increased levels of cytokine (IL-10) and the growth factor (TGF-β), which are related to the anti-inflammatory phase (M2 phenotype). Finally, PGS/PLA-PRP was found to induce a significant level of angiogenesis by forming branching points, loops, and tubes. Based on the results obtained, the PGS/PLA-PRP dressing developed might be a promising evolution in skin tissue engineering ensuring improved wound healing and tissue regeneration.

Merging BioActuation and BioCapacitive properties: A 3D bioprinted devices to self-stimulate using self-stored energy

Biofabrication of three-dimensional (3D) cultures through the 3D Bioprinting technique opens new perspectives and applications of cell-laden hydrogels. However, to continue with the progress, new BioInks with specific properties must be carefully designed. In this study, we report the synthesis and 3D Bioprinting of an electroconductive BioInk made of gelatin/fibrinogen hydrogel, C2C12 mouse myoblast and 5% w/w of conductive poly (3,4-ethylenedioxythiophene) nanoparticles (PEDOT NPs). The influence of PEDOT NPs, incorporated in the cell-laden BioInk, not only showed a positive effect in cells viability, differentiation and myotube functionalities, also allowed the printed constructs to behaved as BioCapacitors. Such devices were able to electrochemically store a significant amount of energy (0.5 mF/cm2), enough to self-stimulate as BioActuator, with typical contractions ranging from 27 to 38 μN, during nearly 50 min. The biofabrication of 3D constructs with the proposed electroconductive BioInk could lead to new devices for tissue engineering, biohybrid robotics or bioelectronics.

MgO@polydopamine Nanoparticle-Loaded Photothermal Microneedle Patches Combined with Chitosan Gel Dressings for the Treatment of Infectious Wounds

As for wound drug delivery, microneedles (MNs) have attracted wide attention. However, while effective at increasing the depth of drug delivery, traditional MNs often have limited drug loads and have difficulty penetrating scabs on wounds. Herein, we develop a drug delivery system combining MgO@polydopamine (MgO@PDA) nanoparticle-loaded photothermal MN patches and chitosan (CS) gel to inhibit the formation of scabs and deliver sufficient drugs into deep tissue. When inserted into the wound, the MN system can keep the wound bed moist and weakly acidic to inhibit the formation of scabs and accelerate wound closure. The released MgO@PDA nanoparticles from both the tips and the backing layer, which immensely increase the drug load, continuously release Mg2+ in the moist, weakly acidic wound bed, promoting tissue migration and the formation of microvessels. MgO@PDA nanoparticles show excellent antibacterial activity under near-infrared irradiation synergized with the CS gel, and the PDA coating can also overcome the adverse effects of oxidative stress. Through in vitro and in vivo experiments, the MN system showed remarkable antibacterial, antioxidant, anti-inflammatory, and pro-angiogenic effects, indicating its potential in the treatment of infectious wounds.

Bacterial Cellulose-Based Bandages with Integrated Antibacteria and Electrical Stimulation for Advanced Wound Management

Bandages for daily wounds are the most common medical supplies, but there are still ingrained defects in their appearance, comfort, functions, as well as environmental pollution. Here, novel bandages based on bacterial cellulose (BC) membrane for wound monitoring and advanced wound management are developed. The BC membrane is combined with silver nanowires (AgNWs) by using vacuum filtration method to achieve transparent, ultrathin (≈7 µm), breathable (389.98-547.79 g m-2  d-1 ), and sandwich-structured BC/AgNWs bandages with superior mechanical properties (108.45-202.35 MPa), antibacterial activities against Escherichia coli and Staphylococcus aureus, biocompatibility, and conductivity (9.8 × 103 -2.0 × 105  S m-1 ). Significantly, the BC/AgNWs bandage is used in the electrical stimulation (direct current, 600  microamperes for 1 h every other day) treatment of full-thickness skin defect in rats, which obviously promotes wound healing by increasing the secretion of vascular endothelial growth factor (VEGF). The BC bandage is used for monitoring wounds and achieve a high accuracy of 94.7% in classifying wound healing stages of hemostasis, inflammation, proliferation, and remodeling, by using a convolutional neural network. The outcomes of this study not only provide two BC-based bandages as multifunctional wound management, but also demonstrate a new strategy for the development of the next generation of smart bandage.

Molecular co-assembled strategy tuning protein conformation for cartilage regeneration

The assembly of oligopeptide and polypeptide molecules can reconstruct various ordered advanced structures through intermolecular interactions to achieve protein-like biofunction. Here, we develop a "molecular velcro"-inspired peptide and gelatin co-assembly strategy, in which amphiphilic supramolecular tripeptides are attached to the molecular chain of gelatin methacryloyl via intra-/intermolecular interactions. We perform molecular docking and dynamics simulations to demonstrate the feasibility of this strategy and reveal the advanced structural transition of the co-assembled hydrogel, which brings more ordered β-sheet content and 10-fold or more compressive strength improvement. We conduct transcriptome analysis to reveal the role of co-assembled hydrogel in promoting cell proliferation and chondrogenic differentiation. Subcutaneous implantation evaluation confirms considerably reduced inflammatory responses and immunogenicity in comparison with type I collagen. We demonstrate that bone mesenchymal stem cells-laden co-assembled hydrogel can be stably fixed in rabbit knee joint defects by photocuring, which significantly facilitates hyaline cartilage regeneration after three months. This co-assembly strategy provides an approach for developing cartilage regenerative biomaterials.

Electrochemical and Electrical Biosensors for Wearable and Implantable Electronics Based on Conducting Polymers and Carbon-Based Materials

Bioelectronic devices are designed to translate biological information into electrical signals and vice versa, thereby bridging the gap between the living biological world and electronic systems. Among different types of bioelectronics devices, wearable and implantable biosensors are particularly important as they offer access to the physiological and biochemical activities of tissues and organs, which is significant in diagnosing and researching various medical conditions. Organic conducting and semiconducting materials, including conducting polymers (CPs) and graphene and carbon nanotubes (CNTs), are some of the most promising candidates for wearable and implantable biosensors. Their unique electrical, electrochemical, and mechanical properties bring new possibilities to bioelectronics that could not be realized by utilizing metals- or silicon-based analogues. The use of organic- and carbon-based conductors in the development of wearable and implantable biosensors has emerged as a rapidly growing research field, with remarkable progress being made in recent years. The use of such materials addresses the issue of mismatched properties between biological tissues and electronic devices, as well as the improvement in the accuracy and fidelity of the transferred information. In this review, we highlight the most recent advances in this field and provide insights into organic and carbon-based (semi)conducting materials' properties and relate these to their applications in wearable/implantable biosensors. We also provide a perspective on the promising potential and exciting future developments of wearable/implantable biosensors.

Oxygen vacancy healing boosts the piezoelectricity of bone scaffolds

Although barium titanate (BaTiO3) presented tremendous potential in achieving self-powered stimulation to accelerate bone repair, pervasive oxygen vacancies restricted the full play of its piezoelectric performance. Herein, BaTiO3-GO nanoparticles were synthesized by the in situ growth of BaTiO3 on graphene oxide (GO), and subsequently introduced into poly-L-lactic acid (PLLA) powders to prepare PLLA/BaTiO3-GO scaffolds by laser additive manufacturing. During the synthesis process, CO and C-OH in GO would respectively undergo cleavage and dehydrogenation at high temperature to form negatively charged oxygen groups, which were expected to occupy positively charged oxygen vacancies in BaTiO3 and thereby inhibit the formation of oxygen vacancies. Moreover, GO could be partially reduced to reduced graphene oxide, which could act as a conductive phase to facilitate polarization charge transfer, thus further improving the piezoelectric performance. The results showed that the oxygen peak at the specific electron binding energy in O 1s declined from 54.4% to 14.6% and the Ti3+ peak that was positively correlated with oxygen vacancies apparently weakened for BaTiO3-GO, illustrating that the introduced GO significantly decreased the oxygen vacancy. As a consequence, the piezoelectric current of PLLA/BaTiO3-GO increased from 80 to 147.3 nA compared with that of PLLA/BaTiO3. The enhanced piezoelectric current effectively accelerated cell differentiation by upregulating alkaline phosphatase expression, calcium salt deposition and calcium influx. This work provides a novel insight for the design of self-powered stimulation scaffolds for bone regeneration.

Stimuli-responsive polysaccharide-based smart hydrogels for diabetic wound healing: Design aspects, preparation methods and regulatory perspectives

Diabetes adversely affects wound-healing responses, leading to the development of chronic infected wounds. Such wound microenvironment is characterized by hyperglycaemia, hyperinflammation, hypoxia, variable pH, upregulation of matrix metalloproteinases, oxidative stress, and bacterial colonization. These pathological conditions pose challenges for the effective wound healing. Therefore, there is a paradigm shift in diabetic wound care management wherein abnormal pathological conditions of the wound microenvironment is used as a trigger for controlling the drug release or to improve properties of wound dressings. Hydrogels composed of natural polysaccharides showed tremendous potential as wound dressings as well as stimuli-responsive materials due to their unique properties such as biocompatibility, biodegradability, hydrophilicity, porosity, stimuli-responsiveness etc. Hence, polysaccharide-based hydrogels have emerged as advanced healthcare materials for diabetic wounds. In this review, we presented important aspects for the design of hydrogel-based wound dressings with an emphasis on biocompatibility, biodegradability, entrapment of therapeutic agents, moisturizing ability, swelling, and mechanical properties. Further, various crosslinking methods that enable desirable properties and stimuli responsiveness to the hydrogels have been mentioned. Subsequently, state-of-the-art developments in mono- and multi- stimuli-responsive hydrogels have been presented along with the case studies. Finally regulatory perspectives, challenges for the clinical translation and future prospects have been discussed.

Conductive and Eco-friendly Biomaterials-based Hydrogels for Noninvasive Epidermal Sensors: A Review

As noninvasive wearable electronic devices, epidermal sensors enable continuous, real-time, and remote monitoring of various human physiological parameters. Conductive biomaterials-based hydrogels as sensor matrix materials have good biocompatibility, biodegradability, and efficient stimulus response capabilities and are widely applied in motion monitoring, healthcare, and human-machine interaction. However, biomass hydrogel-based epidermal sensing devices still need excellent mechanical properties, prolonged stability, multifunctionality, and extensive practicality. Therefore, this paper reviews the common biomass hydrogel materials for epidermal sensing (proteins, polysaccharides, polyphenols, etc.) and the various types of noninvasive sensing devices (strain/pressure sensors, temperature sensors, glucose sensors, electrocardiograms, etc.). Moreover, this review focuses on the strategies of scholars to enhance sensor properties, such as strength, conductivity, stability, adhesion, and self-healing ability. This work will guide the preparation and optimization of high-performance biomaterials-based hydrogel epidermal sensors.

Diphylleia Grayi-Inspired Intelligent Temperature-Responsive Transparent Nanofiber Membranes

Nanofiber membranes (NFMs) have become attractive candidates for next-generation flexible transparent materials due to their exceptional flexibility and breathability. However, improving the transmittance of NFMs is a great challenge due to the enormous reflection and incredibly poor transmission generated by the nanofiber-air interface. In this research, we report a general strategy for the preparation of flexible temperature-responsive transparent (TRT) membranes, which achieves a rapid transformation of NFMs from opaque to highly transparent under a narrow temperature window. In this process, the phase change material eicosane is coated on the surface of the polyurethane nanofibers by electrospray technology. When the temperature rises to 37 °C, eicosane rapidly completes the phase transition and establishes the light transmission path between the nanofibers, preventing light loss from reflection at the nanofiber-air interface. The resulting TRT membrane exhibits high transmittance (> 90%), and fast response (5 s). This study achieves the first TRT transition of NFMs, offering a general strategy for building highly transparent nanofiber materials, shaping the future of next-generation intelligent temperature monitoring, anti-counterfeiting measures, and other high-performance devices.

Fundamental properties of smart hydrogels for tissue engineering applications: A review

Tissue engineering is an advanced and potential biomedical approach to treat patients suffering from lost or failed an organ or tissue to repair and regenerate damaged tissues that increase life expectancy. The biopolymers have been used to fabricate smart hydrogels to repair damaged tissue as they imitate the extracellular matrix (ECM) with intricate structural and functional characteristics. These hydrogels offer desired and controllable qualities, such as tunable mechanical stiffness and strength, inherent adaptability and biocompatibility, swellability, and biodegradability, all crucial for tissue engineering. Smart hydrogels provide a superior cellular environment for tissue engineering, enabling the generation of cutting-edge synthetic tissues due to their special qualities, such as stimuli sensitivity and reactivity. Numerous review articles have presented the exceptional potential of hydrogels for various biomedical applications, including drug delivery, regenerative medicine, and tissue engineering. Still, it is essential to write a comprehensive review article on smart hydrogels that successfully addresses the essential challenging issues in tissue engineering. Hence, the recent development on smart hydrogel for state-of-the-art tissue engineering conferred progress, highlighting significant challenges and future perspectives. This review discusses recent advances in smart hydrogels fabricated from biological macromolecules and their use for advanced tissue engineering. It also provides critical insight, emphasizing future research directions and progress in tissue engineering.

Advancements in gelatin-based hydrogel systems for biomedical applications: A state-of-the-art review

A gelatin-based hydrogel system is a stimulus-responsive, biocompatible, and biodegradable polymeric system with solid-like rheology that entangles moisture in its porous network that gradually protrudes to assemble a hierarchical crosslinked arrangement. The hydrolysis of collagen directs gelatin construction, which retains arginyl glycyl aspartic acid and matrix metalloproteinase-sensitive degeneration sites, further confining access to chemicals entangled within the gel (e.g., cell encapsulation), modulating the release of encapsulated payloads and providing mechanical signals to the adjoining cells. The utilization of various types of functional tunable biopolymers as scaffold materials in hydrogels has become highly attractive due to their higher porosity and mechanical ability; thus, higher loading of proteins, peptides, therapeutic molecules, etc., can be further modulated. Furthermore, a stimulus-mediated gelatin-based hydrogel with an impaired concentration of gellan demonstrated great shear thinning and self-recovering characteristics in biomedical and tissue engineering applications. Therefore, this contemporary review presents a concise version of the gelatin-based hydrogel as a conceivable biomaterial for various biomedical applications. In addition, the article has recapped the multiple sources of gelatin and their structural characteristics concerning stimulating hydrogel development and delivery approaches of therapeutic molecules (e.g., proteins, peptides, genes, drugs, etc.), existing challenges, and overcoming designs, particularly from drug delivery perspectives.

CuS@TA-Fe Nanoparticle-Doped Multifunctional Hydrogel with Peroxide-Like Properties and Photothermal Properties for Synergistic Antimicrobial Repair of Infected Wounds

Bacterial infection is a critical factor in wound healing. Due to the abuse of antibiotics, some pathogenic bacteria have developed resistance. Thus, there is an urgent need to develop a non-antibiotic-dependent multifunctional wound dressing for the treatment of bacteria-infected wounds. In this work, a multifunctional AOCuT hydrogel embedded with CuS@TA-Fe nanoparticles (NPs) through Schiff base reaction between gelatin quaternary ammonium salt - gallic acid (O-Gel-Ga) and sodium dialdehyde alginate (ADA) along with electrostatic interactions with CuS@TA-Fe NPs is prepared. These composite hydrogels possess favorable injectability, rapid shape adaptation, electrical conductivity, photothermal antimicrobial activity, and biocompatibility. Additionally, the doped NPs not only impart fast self-healing properties and excellent adhesion performance to the hydrogels, but also provide excellent peroxide-like properties, enabling them to scavenge free radicals and exhibit anti-inflammatory and antioxidant capabilities via photothermal (PTT) and photodynamic (PDT) effects. In an S. aureus infected wound model, the composite hydrogel effectively reduces the expression level of wound inflammatory factors and accelerates collagen deposition, epithelial tissue, and vascular regeneration, thereby promoting wound healing. This safe and synergistic therapeutic system holds great promise for clinical applications in the treatment of infectious wounds.

Metal-Phenolic Networks for Chronic Wounds Therapy

Chronic wounds are recalcitrant complications of a variety of diseases, with pathologic features including bacterial infection, persistent inflammation, and proliferation of reactive oxygen species (ROS) levels in the wound microenvironment. Currently, the use of antimicrobial drugs, debridement, hyperbaric oxygen therapy, and other methods in clinical for chronic wound treatment is prone to problems such as bacterial resistance, wound expansion, and even exacerbation. In recent years, researchers have proposed many novel materials for the treatment of chronic wounds targeting the disease characteristics, among which metal-phenolic networks (MPNs) are supramolecular network structures that utilize multivalent metal ions and natural polyphenols complexed through ligand bonds. They have a flexible and versatile combination of structural forms and a variety of formations (nanoparticles, coatings, hydrogels, etc.) that can be constructed. Functionally, MPNs combine the chemocatalytic and bactericidal properties of metal ions as well as the anti-inflammatory and antioxidant properties of polyphenol compounds. Together with the excellent properties of rapid synthesis and negligible cytotoxicity, MPNs have attracted researchers' great attention in biomedical fields such as anti-tumor, anti-bacterial, and anti-inflammatory. This paper will focus on the composition of MPNs, the mechanisms of MPNs for the treatment of chronic wounds, and the application of MPNs in novel chronic wound therapies.

Tough polyvinyl alcohol-gelatin biological macromolecules ionic hydrogel temperature, humidity, stress and strain, sensors

High strength, high toughness and high sensitivity were some of the most popular characteristics of flexible sensors. However, the mechanical properties and reproducibility of current single biomacromolecule gelatin hydrogel sensors are lower, and few hydrogel sensors have been able to provide excellent mechanical properties and flexibility at the same time so far. To address this challenge, a simple method to prepare tough polyvinyl alcohol (PVA) and gelatin hydrogel was proposed in this study. The PVA-gelatin-Fe3+ biological macromolecules hydrogel was prepared by a freeze-casting-assisted solution substitution method, which exhibited high strength (2.5 MPa), toughness (7.22 MJ m-3), and excellent temperature, humidity, stress, strain, and human motion sensing properties. This combination of mechanical properties and flexibility makes PVA-gelatin biological macromolecules hydrogel a promising material for flexible sensing. In addition, an ionic immersion strategy could also impart multiple functions to the hydrogel and be applied to various hydrogel sensor materials. Thus, this work provided an all-around solution for the preparation of advanced and robust sensors with good application prospects.

Multi-functional conductive hydrogels based on heparin-polydopamine complex reduced graphene oxide for epidermal sensing and chronic wound healing

Flexible hydrogel sensors have expanded the applications of electronic devices due to their suitable mechanical properties and excellent biocompatibility. However, conventionally synthesized reduced graphene oxide (rGO) encounters limitations in reduction degree and dispersion, restricting the conductivity of graphene hydrogels and impeding the development of high-sensitivity flexible sensors. Moreover, hydrogels are susceptible to inflammation and bacterial infections, jeopardizing sensor stability over time. Thus, the challenge persists in designing conductive hydrogels that encompass high sensitivity, antibacterial efficacy, and anti-oxidative capabilities. In this study, GO was modified and reduced via a heparin-polydopamine (Hep-PDA) complex, yielding well-reduced and uniformly dispersed Hep-PDA-rGO nanosheets. Consequently, a hydrogel utilizing Hep-PDA-rGO was synthesized, showcasing commendable conductivity (3.63 S/m) and sensor performance, effectively applied in real-time motion monitoring. Notably, the hydrogel's attributes extend to facilitating chronic diabetic wound healing. It maintained a suitable inflammatory environment credited to its potent antibacterial and antioxidative properties, while its inherent conductivity promoted angiogenesis. The multifunctional nature of this hydrogel highlight its potential not only as an epidermal sensor but also as a promising dressing candidate for chronic wound treatment.

Nature-Skin-Derived e-Skin as Versatile "Wound Therapy-Health Monitoring" Bioelectronic Skin-Scaffolds: Skin to Bio-e-Skin

Electronic skins (e-skins) have the potential to turn into breakthroughs in biomedical applications. Herein, a novel acellular dermal matrix (ADM)-based bioelectronic skin (e-ADM) is used to fabricate versatile "wound therapy-health monitoring" tissue-nanoengineered skin scaffolds via a facile "one-pot" bio-compositing strategy to incorporate the conductive carbon nanotubes and self-assembled micro-copper oxide microspheres with a cicada-wing-like rough surface and nanocone microstructure. The e-ADM exhibits robust tensile strength (22 MPa), flexibility, biodegradability, electroactivity, and antibacterial properties. Interestingly, e-ADM exhibits the pH-responsive ability for intelligent command between sterilization and wound repair . Additionally, e-ADM enables accurate real-time monitoring of human activities, providing a novel flexible e-skin sensor to record injury and motions. In vitro and in vivo experiments show that with electrical stimulation, e-ADM could prominently facilitate cell growth and proliferation and further promote full-thickness skin wound healing, providing a comprehensive therapeutic strategy for smart sensing and tissue repair, guiding the development of high-performance "wound therapy-health monitoring" bioelectronic skin-scaffolds.

Structurally dynamic self-healable hydrogel cooperatively inhibits intestinal inflammation and promotes mucosal repair for enhanced ulcerative colitis treatment

Hydrogels are a class of biocompatible materials with versatile functions that have been increasing explored for the localized treatment of ulcerative colitis (UC), but various mechanical stimuli may cause premature hydrogel breakage and detachment, impeding their further clinical translation. Here we report a multifunctional mechanically-resilient self-healing hydrogel for effective UC treatment, which is synthesized through the host-guest interaction between dopamine/β-cyclodextrin-modified hyaluronic acid (HA-CD-DA) and amantadine-modified carboxymethyl chitosan (CMCS-AD). The excessive β-CD cavities allow the incorporation of dexamethasone (DEX), while the porous hydrogel network potentiates the encapsulation of basic fibroblast growth factor (bFGF) and L-alanyl-l-glutamine (ALG). DA moieties in HA components allow firm adhesion of the hydrogel to the ulcerative lesions after in-situ implantation, while the reversible host-guest interaction between CD and AD could enhance the persistence of hydrogel. The hydrogel demonstrated favorable biocompatibility and could continuously release DEX to induce M1-to-M2 repolarization of mucosal macrophages through inhibiting the toll-like receptor 4 (TLR4)-nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) axis. Furthermore, the co-delivered bFGF and ALG facilitates the regeneration of ulcerative mucosa and restore its barrier functions to ameliorate UC symptoms. The mechanically resilient hydrogel offers an integrative approach for UC therapy in the clinics.

A conductive multifunctional hydrogel dressing with the synergistic effect of ROS-scavenging and electroactivity for the treatment and sensing of chronic diabetic wounds

Chronic diabetic wound with persistent inflammatory responses is still a serious threat to human health and life. Ideal wound dressings can be applied not only for covering the injury area, but also for regulating the inflammation to accelerate the wound healing and long-term monitoring of wound condition. However, there remains a challenge to design a multifunctional wound dressing for simultaneous treatment and monitoring of wound. Herein, an ionic conductive hydrogel with intrinsic reactive oxygen species (ROS)-scavenging properties and good electroactivity was developed for achieving the synergetic treatment and monitoring of diabetic wounds. In this study, we modified dextran methacrylate with phenylboronic acid (PBA) to prepare a ROS-scavenging material (DMP). Then the hydrogel was constructed by phenylboronic ester bonds induced dynamic crosslinking network, photo-crosslinked DMP and choline-based ionic liquid as the second network, and the crystallized polyvinyl alcohol as the third network, realizing good ROS-scavenging performance, high electroactivity, durable mechanical properties, and favorable biocompatibility. In vivo results showed that the hydrogel combined with electrical stimulation (ES) demonstrated good performance in promoting re-epithelization, angiogenesis and collagen deposition in chronic diabetic wound treatment by alleviating inflammation. Notably, with desirable mechanical properties and conductivity, the hydrogel could also precisely monitor movements of human body and possible tensile and compressive stresses of the wound site, providing timely alerts of excessive mechanical stress applied to the wound tissue. Thus, this "all-in-one" hydrogel exhibits great potential in constructing the next generation flexible bioelectronics for wound treatment and monitoring. STATEMENT OF SIGNIFICANCE: : Chronic diabetic wounds characterized by overexpressed reactive oxygen species (ROS) are still a serious threat to human health and life. However, there remains a challenge to design a multifunctional wound dressing for simultaneous wound treatment and monitoring. Herein, a flexible conductive hydrogel dressing with intrinsic ROS-scavenging properties and electroactivity was developed for the combined treatment and monitoring of the wound. The antioxidant hydrogel combined with electrical stimulation synergistically accelerated chronic diabetic wound healing by regulating oxidative stress, alleviating inflammation, promoting re-epithelization, angiogenesis and collagen deposition. Notably, with desirable mechanical properties and conductivity, the hydrogel also presented great potential in monitoring possible stresses of the wound site. The "all-in-one" bioelectronics integrating the treatment and monitoring functions present great application potential for accelerating chronic wound healing.

Skin-interfaced electronics: A promising and intelligent paradigm for personalized healthcare

Skin-interfaced electronics (skintronics) have received considerable attention due to their thinness, skin-like mechanical softness, excellent conformability, and multifunctional integration. Current advancements in skintronics have enabled health monitoring and digital medicine. Particularly, skintronics offer a personalized platform for early-stage disease diagnosis and treatment. In this comprehensive review, we discuss (1) the state-of-the-art skintronic devices, (2) material selections and platform considerations of future skintronics toward intelligent healthcare, (3) device fabrication and system integrations of skintronics, (4) an overview of the skintronic platform for personalized healthcare applications, including biosensing as well as wound healing, sleep monitoring, the assessment of SARS-CoV-2, and the augmented reality-/virtual reality-enhanced human-machine interfaces, and (5) current challenges and future opportunities of skintronics and their potentials in clinical translation and commercialization. The field of skintronics will not only minimize physical and physiological mismatches with the skin but also shift the paradigm in intelligent and personalized healthcare and offer unprecedented promise to revolutionize conventional medical practices.

In situ forming ROS-scavenging hybrid hydrogel loaded with polydopamine-modified fullerene nanocomposites for promoting skin wound healing

BACKGROUND

Excessive oxidative stress at the wound sites always leads to a prolonged healing and even causes chronic inflammatory wounds. Therefore, antioxidative dressings with multiple features are desired to improve wound healing performance. Herein, we fabricated a ROS-scavenging hybrid hydrogel by incorporating mussel-inspired fullerene nanocomposites (C60@PDA) into gelatin methacryloyl (GelMA) hydrogel.

RESULTS

The developed C60@PDA/GelMA hydrogel showed a sustainable free radical scavenging ability, and eliminated ROS to protect cells against external oxidative stress damage. Besides, the hydrogel presented favorable cytocompatibility, hemocompatibility, and antibacterial ability in vitro. Furthermore, in a mouse full-thickness wound defect model, the in situ forming hybrid hydrogel accelerated wound closure by 38.5% and 42.9% on day 3 and day 7 over the control. Histological results demonstrated that hybrid hydrogels effectively enhanced wound healing on re-epithelialization, collagen deposition and angiogenesis.

CONCLUSION

Collectively, the C60@PDA/GelMA hydrogel could be a promising dressing for promoting cutaneous wound repair.

Conductive hydrogels for tissue repair

Conductive hydrogels (CHs) combine the biomimetic properties of hydrogels with the physiological and electrochemical properties of conductive materials, and have attracted extensive attention in the past few years. In addition, CHs have high conductivity and electrochemical redox properties and can be used to detect electrical signals generated in biological systems and conduct electrical stimulation to regulate the activities and functions of cells including cell migration, cell proliferation, and cell differentiation. These properties give CHs unique advantages in tissue repair. However, the current review of CHs is mostly focused on their applications as biosensors. Therefore, this article reviewed the new progress of CHs in tissue repair including nerve tissue regeneration, muscle tissue regeneration, skin tissue regeneration and bone tissue regeneration in the past five years. We first introduced the design and synthesis of different types of CHs such as carbon-based CHs, conductive polymer-based CHs, metal-based CHs, ionic CHs, and composite CHs, and the types and mechanisms of tissue repair promoted by CHs including anti-bacterial, antioxidant and anti-inflammatory properties, stimulus response and intelligent delivery, real-time monitoring, and promoted cell proliferation and tissue repair related pathway activation, which provides a useful reference for further preparation of bio-safer and more efficient CHs used in tissue regeneration.

Smart microneedle patches for wound healing and management

The number of patients with non-healing wounds is generally increasing globally, placing a huge social and economic burden on every country. The complexity of the wound-healing process remains a major health challenge despite the numerous studies that have been reported on conventional wound dressings. Therefore, a therapeutic system that combines diagnostic and therapeutic modalities is essential to monitor wound-related biomarkers and facilitate wound healing in real time. Microneedles, as a multifunctional platform, are promising for transdermal diagnostics and drug delivery. Their advantages are mainly reflected in painless transdermal drug delivery, good biocompatibility, and ease of self-administration. In this work, we review recent advances in the use of microneedle patches for wound healing and monitoring. The paper first provides a brief overview of the skin structure and the wound healing process, and then discusses the current state of research and prospects for the development of wound-related biomarkers and their real-time monitoring based on microneedle sensors. It summarizes the current state of research based on the unique design of microneedle patches, including biomimetic, conductive, and environmentally responsive, to achieve wound healing. It further summarizes the prospects for the application of different microneedle-based drug delivery modalities and drug delivery substances for wound healing, due to their superior transdermal drug delivery advantages. It concludes with challenges and expectations for the use of smart microneedle patches for wound healing and management.

Highly Stretchable and Biocompatible Wrinkled Nanoclay-Composite Hydrogel With Enhanced Sensing Capability for Precise Detection of Myocardial Infarction

It is challenging to balance high biocompability with good mechanical-electrical sensing performance, especially when triggering inflammatory stress response after in vivo implantation. Herein, a bioinspired wrinkle-reinforced adaptive nanoclay-interlocked soft strain-sensor based on a highly stretchable and elastic ionic-conductive hydrogel is reported. This novel nanoclay-composite hydrogel exhibits excellent tensile properties and high sensing capacity with steady and reliable sensing performance due to the structural-mechanical-electrical integrity of the nanoclay crosslinked and nano-reinforced interpenetrating network. The incorporation of amphiphilic ions provides the hydrogel with significant protein resistance, reducing its non-specific adsorption to proteins upon implantation, improving its biosafety as an implanted device, and maintaining the authenticity of the sensing results. Based on the revealed sensing enhanced mechanism based on hierarchical ordered structures as a proof-of-concept application, this hydrogel sensor is demonstrated to be able to accurately localize the region where myocardial infarction occurs and may become a novel strategy for real-time monitoring of pathological changes in heart disease.

3D Bioelectronics with a Remodellable Matrix for Long-Term Tissue Integration and Recording

Bioelectronics hold the key for understanding and treating disease. However, achieving stable, long-term interfaces between electronics and the body remains a challenge. Implantation of a bioelectronic device typically initiates a foreign body response, which can limit long-term recording and stimulation efficacy. Techniques from regenerative medicine have shown a high propensity for promoting integration of implants with surrounding tissue, but these implants lack the capabilities for the sophisticated recording and actuation afforded by electronics. Combining these two fields can achieve the best of both worlds. Here, the construction of a hybrid implant system for creating long-term interfaces with tissue is shown. Implants are created by combining a microelectrode array with a bioresorbable and remodellable gel. These implants are shown to produce a minimal foreign body response when placed into musculature, allowing one to record long-term electromyographic signals with high spatial resolution. This device platform drives the possibility for a new generation of implantable electronics for long-term interfacing.

Hydrogel-Integrated Multimodal Response as a Wearable and Implantable Bidirectional Interface for Biosensor and Therapeutic Electrostimulation

A hydrogel that fuses long-term biologic integration, multimodal responsiveness, and therapeutic functions has received increasing interest as a wearable and implantable sensor but still faces great challenges as an all-in-one sensor by itself. Multiple bonding with stimuli response in a biocompatible hydrogel lights up the field of soft hydrogel interfaces suitable for both wearable and implantable applications. Given that, we proposed a strategy of combining chemical cross-linking and stimuli-responsive physical interactions to construct a biocompatible multifunctional hydrogel. In this hydrogel system, ureidopyrimidinone/tyramine (Upy/Tyr) difunctionalization of gelatin provides abundant dynamic physical interactions and stable covalent cross-linking; meanwhile, Tyr-doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) acts as a conductive filler to establish electrical percolation networks through enzymatic chemical cross-linking. Thus, the hydrogel is characterized with improved conductivity, conformal biointegration features (i.e., high stretchability, rapid self-healing, and excellent tissue adhesion), and multistimuli-responsive conductivity (i.e., temperature and urea). On the basis of these excellent performances, the prepared multifunctional hydrogel enables multimodal wearable sensing integration that can simultaneously track both physicochemical and electrophysiological attributes (i.e., motion, temperature, and urea), providing a more comprehensive monitoring of human health than current wearable monitors. In addition, the electroactive hydrogel here can serve as a bidirectional neural interface for both neural recording and therapeutic electrostimulation, bringing more opportunities for nonsurgical diagnosis and treatment of diseases.

An ECM-Mimicking, Injectable, Viscoelastic Hydrogel for Treatment of Brain Lesions

Brain lesions can arise from traumatic brain injury, infection, and craniotomy. Although injectable hydrogels show promise for promoting healing of lesions and health of surrounding tissue, enabling cellular ingrowth and restoring neural tissue continue to be challenging. It is hypothesized that these challenges arise in part from the mismatch of composition, stiffness, and viscoelasticity between the hydrogel and the brain parenchyma, and this hypothesis is tested by developing and evaluating a self-healing hydrogel that not only mimics the composition, but also the stiffness and viscoelasticity of native brain parenchyma. The hydrogel is crosslinked by dynamic boronate ester bonds between phenylboronic acid grafted hyaluronic acid (HA-PBA) and dopamine grafted gelatin (Gel-Dopa). This HA-PBA/Gel-Dopa hydrogel could be injected into a lesion cavity in a shear-thinning manner with rapid hemostasis, high tissue adhesion, and efficient self-healing. In an in vivo mouse model of brain lesions, the multi-functional injectable hydrogel is found to support neural cell infiltration, decrease astrogliosis and glial scars, and close the lesions. The results suggest a role for extracellular matrix-mimicking viscoelasticity in brain lesion healing, and motivate additional experimentation in larger animals as the technology progresses toward potential application in humans.

Nanomaterials-Functionalized Hydrogels for the Treatment of Cutaneous Wounds

Hydrogels have been utilized extensively in the field of cutaneous wound treatment. The introduction of nanomaterials (NMs), which are a big category of materials with diverse functionalities, can endow the hydrogels with additional and multiple functions to meet the demand for a comprehensive performance in wound dressings. Therefore, NMs-functionalized hydrogels (NMFHs) as wound dressings have drawn intensive attention recently. Herein, an overview of reports about NMFHs for the treatment of cutaneous wounds in the past five years is provided. Firstly, fabrication strategies, which are mainly divided into physical embedding and chemical synthesis of the NMFHs, are summarized and illustrated. Then, functions of the NMFHs brought by the NMs are reviewed, including hemostasis, antimicrobial activity, conductivity, regulation of reactive oxygen species (ROS) level, and stimulus responsiveness (pH responsiveness, photo-responsiveness, and magnetic responsiveness). Finally, current challenges and future perspectives in this field are discussed with the hope of inspiring additional ideas.

Next-Generation Diagnostic Wound Dressings for Diabetic Wounds

Chronic lower extremity wounds (diabetic foot ulcers) are a serious and prevalent complication of diabetes. These wounds exhibit low healing rates and present a high risk of amputation. Current diagnostic options for foot ulcers are limited to macroscopic wound analysis such as wound depth, implicated tissues, and infection. Molecular diagnostics promises to improve foot ulcer diagnosis, staging, and assessment of the treatment response. In this perspective, we report recent progress in understanding the pathophysiology of diabetic wound healing and point to recently emerged novel molecular targets for wound diagnostics. We discuss selected diagnostic wound dressings under preclinical development that detect one or several inflammatory markers, bacterial secretions, hyperglycemia, and mechanical stress. We also highlight key translational challenges of investigational diagnostic bandages for diabetic foot ulcers.

Adhesive Gelatin-Catechol Complex Reinforced Poly(Acrylic Acid) Hydrogel with Enhanced Toughness and Cell Affinity for Cartilage Regeneration

The repair of cartilage damage caused by trauma, wear, or degenerative deformation remains a major challenge in modern medicine. Therefore, it is essential to develop a mechanically compatible and bioactive scaffold for cartilage tissue regeneration. In this study, a mussel-inspired, tough, adhesive polydopamine/gelatin-poly(acrylic acid) (PDA/Gel-PAA) composite hydrogel was developed for cartilage regeneration. The hydrogel achieved a high compressive strength of up to 0.67 MPa and a toughness of 420 J/m2 because of the unique chemical-physical cross-linking structure by introducing the PDA/Gel complex into the PAA network. PAA chains with rich carboxyl groups mimic the negatively charged glycosaminoglycans (GAGs) in the natural cartilage extracellular matrix (ECM), leading to strong water retention in the hydrogel. The incorporation of the PDA/Gel complex with catechol groups on PDA and arginine-glycine-aspartic acid (RGD) sequences on gelatin chains provided abundant adhesive motifs to improve the cell affinity and tissue adhesiveness of PAA, thereby facilitating the adhesion and proliferation of bone marrow stromal cells (BMSCs). In addition, transforming growth factor-β3 (TGFβ3) was stably immobilized and released from the PDA/Gel-PAA hydrogel. Thus, adhesive hydrogels can provide a suitable microenvironment to promote cell migration in the defect area and induce chronogenesis for cartilage regeneration.

Progress in Gelatin as Biomaterial for Tissue Engineering

Tissue engineering has become a medical alternative in this society with an ever-increasing lifespan. Advances in the areas of technology and biomaterials have facilitated the use of engineered constructs for medical issues. This review discusses on-going concerns and the latest developments in a widely employed biomaterial in the field of tissue engineering: gelatin. Emerging techniques including 3D bioprinting and gelatin functionalization have demonstrated better mimicking of native tissue by reinforcing gelatin-based systems, among others. This breakthrough facilitates, on the one hand, the manufacturing process when it comes to practicality and cost-effectiveness, which plays a key role in the transition towards clinical application. On the other hand, it can be concluded that gelatin could be considered as one of the promising biomaterials in future trends, in which the focus might be on the detection and diagnosis of diseases rather than treatment.

Architecting polyelectrolyte hydrogels with Cu-assisted polydopamine nanoparticles for photothermal antibacterial therapy

Polydopamine nanoparticles (PDA NPs) are an appealing biomimetic photothermal agent for photothermal antibacterial treatment because of their long-term safety, excellent photostability, accessible manufacturing, and good biodegradability. However, the low photothermal conversion efficiency (PCE) of PDA NPs requires high-power and long-term near-infrared light irradiation, which severely restricts their practical application. In this work, PDA@Cu NPs were fabricated by growing Cu NPs in situ on the surface of PDA and then introduced into a polyelectrolyte hydrogel precursor (cationic polyethyleneimine/anionic pectin, named as CPAP). The formulated photothermal platform possessed a high PCE (55.4%), almost twice as much as pure PDA NPs (30.8%). Moreover, the designed CPAP/PDA@Cu captured and killed some bacteria by electrostatic adsorption, which helped enhance the antibacterial performance. As expected, the formed CPAP/PDA@Cu that combined the advantageous features of PDA@Cu NPs (high PCE) and CPAP matrix (inherent antibacterial activity and preventing NPs aggregation) can efficiently kill bacteria both in vitro and in vivo under the help of near-infrared laser irradiation. Taken together, this study offers a promising strategy for constructing a facile and safe PDA-based photothermal agent for photothermal antibacterial therapy.

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A facile polyelectrolyte photothermal antibacterial platform (CPAP) was synthesized.

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CPAP is composed of polyethyleneimine, pectin and polydopamine@Cu nanoparticles.

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CPAP displayed good biocompatibility and tunable physicochemical properties.

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CPAP possessed outstanding high-efficiency bacteria-killing capability.

Recent Progress in Materials Chemistry to Advance Flexible Bioelectronics in Medicine

Designing bioelectronic devices that seamlessly integrate with the human body is a technological pursuit of great importance. Bioelectronic medical devices that reliably and chronically interface with the body can advance neuroscience, health monitoring, diagnostics, and therapeutics. Recent major efforts focus on investigating strategies to fabricate flexible, stretchable, and soft electronic devices, and advances in materials chemistry have emerged as fundamental to the creation of the next generation of bioelectronics. This review summarizes contemporary advances and forthcoming technical challenges related to three principal components of bioelectronic devices: i) substrates and structural materials, ii) barrier and encapsulation materials, and iii) conductive materials. Through notable illustrations from the literature, integration and device fabrication strategies and associated challenges for each material class are highlighted.

Conductive Adhesive and Antibacterial Zwitterionic Hydrogel Dressing for Therapy of Full-Thickness Skin Wounds

Any sort of wound injury leads to the destruction of skin integrity and wound formation, causing millions of deaths every year and accounting for 10% of death rate insight into various diseases. The ideal biological wound dressings are expected to possess extraordinary mechanical characterization, cytocompatibility, adhesive properties, antibacterial properties, and conductivity of endogenous electric current to enhance the wound healing process. Recent studies have demonstrated that biomedical hydrogels can be used as typical wound dressings to accelerate the whole healing process due to them having a similar composition structure to skin, but they are also limited by ideal biocompatibility and stable mechanical properties. To extend the number of practical candidates in the field of wound healing, we designed a new structural zwitterion poly[3-(dimethyl(4-vinylbenzyl) ammonium) propyl sulfonate] (SVBA) into a poly-acrylamide network, with remarkable mechanical properties, stable rheological property, effective antibacterial properties, strong adsorption, high penetrability, and good electroactive properties. Both in vivo and in vitro evidence indicates biocompatibility, and strong healing efficiency, indicating that poly (AAm-co-SVBA) (PAS) hydrogels as new wound healing candidates with biomedical applications.

Antibacterial, antioxidant and anti-inflammatory PLCL/gelatin nanofiber membranes to promote wound healing

Epigallocatechin-3-O-gallate (EGCG) is a green biomedical agent for promoting wound healing, which possess excellent antibacterial, antioxidant and anti-inflammatory activities. For improving the low bioavailability challenges of EGCG in vivo, we had successful created a low-cost and simple wound dressing Poly (L-Lactic-co-caprolactone) (PLCL)/Gelatin/EGCG/Core-shell nanofiber membrane (PGEC) with drug sustained release capacity through coaxial electrospinning technology. In vitro experimental indicated that the core-shell structure wound dressing had excellent biocompatibility, antibacterial and antioxidant ability, which could support cell viability and proliferation, encourage re-epithelialization during the healing process, inhibit subsequent wound infection and thus promote wound regeneration. In vivo experimental demonstrated that PGEC wound dressing could promote wound healing, the histological results further demonstrated that PGEC not only facilitated early wound closure but also influenced cellular differentiation and tissue organization. Meanwhile, PGEC had excellent hemostatic ability. Taken all together, we believed that the PGEC wound dressing, which could localize delivery of EGCG, had high potential clinical application for promoting wound healing, hemostasis or other related clinical applications in the future.

A Mg2+/polydopamine composite hydrogel for the acceleration of infected wound healing

Bacterial infection is a vital factor to delay the wound healing process. The antibiotics abuse leads to drug resistance of some pathogenic bacteria. Non-antibiotic-dependent multifunctional biomaterials with accelerated wound healing performance are urgently desired. Herein, we reported a composite antibacterial hydrogel PDA-PAM/Mg²⁺ that shows excellent self-healing and tissue adhesive property, and photothermal antibacterial functions for accelerating wound healing. The gel was composed of polyacrylamide (PAM), polydopamine (PDA), and magnesium (Mg²⁺) and prepared via a two-step procedure: an alkali-induced dopamine pre-polymerization and followed radical polymerization process. The composite gel shows excellent tissue adhesiveness and Mg²⁺-synergized photothermal antibacterial activity, inducing a survival rate of 5.29% for S. aureus and 7.06% for E. coli after near infrared light irradiation. The composite hydrogel further demonstrated efficient bacteria inhibition, enhanced wound healing and collagen deposition in a full-thickness skin defect rat model. Together, the PDA-PAM/Mg²⁺ hydrogel presents an excellent wound dressing with excellent tissue adhesion, wound healing, and antibacterial functions.

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A self-healing multifunctional hydrogel with photothermal antibacterial properties was developed and applied in wound healing.

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The hydrogel exhibited enhanced self-healing and adhesion properties.

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The hydrogel exhibited excellent photothermal effect and photothermal stability and repeatability.

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The hydrogel could accelerate wound healing by promoting cell proliferation and collagen deposition.