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In recent years, natural substance‐based tissue adhesive hydrogels have been widely studied by researchers because of their practicability and affordability. In this review, we summarized the design principles and mechanisms for constructing natural substance‐based tissue adhesive hydrogels from the perspective of polyphenols (catechol, dopamine, tannic acid), cationic polymers (chitosan, lysine, cationic antibacterial peptides), polysaccharides and other natural substances. In addition, according to the morphology and size of tissue adhesive hydrogels, it was divided into macroscopic hydrogels and microscopic hydrogels. Therefore, the natural substance‐based adhesive macroscopic hydrogels such as injectable hydrogels and hydrogel patches and natural substance‐based adhesive microscopic hydrogels including hydrogel microspheres were reviewed. Furthermore, we summarized the review and provided outlook based on the present tissue adhesive hydrogels. The review aimed to summarize the progress in natural substance‐based tissue adhesive hydrogels and provide a valuable reference for the development of tissue adhesive hydrogels and its applications in biomedical field. [ABSTRACT FROM AUTHOR]

Silica nanoparticles are innovative solutions of surgical glue that can readily adhere to various tissue-like substrates without the need for time-consuming chemical reactions or ultraviolet irradiation. Herein, 10 nm-sized silica nanoparticle (SiNP10) treatment exhibited maximum adhesion strength in the porcine heart tissue model, which was approximately 7.15 times higher than that of the control group of non-treatment. We assessed the effects of silica nanoparticle treatment on in vivo skin wounds by scoring tissue adhesion and inflammation using histological images. Compared to the commercial cyanoacrylate skin adhesive (Dermabond), suppression of inflammatory cytokine levels in the incision wound skin was observed. We further quantified the expression of angiogenic growth factors and connective tissue formation-related proteins. On day 5 after wound closing treatment, the expression levels of PDGF-BB growth factor were significantly higher in SiNP10 treatment (0.64 ± 0.03) compared to Dermabond (0.07 ± 0.05). This stimulated angiogenesis and connective tissue formation in the skin of the incision wound may be associated with the promoting effects of SiNP10 treatment on wound closure and tissue adhesion. [ABSTRACT FROM AUTHOR]

Oral ulcers can significantly reduce the life quality of patients and even lead to malignant transformations. Local treatments using topical agents are often ineffective because of the wet and dynamic environment of the oral cavity. Current clinical treatments for oral ulcers, such as corticosteroids, have limitations and side effects for long-term usage. Here, we develop adhesive hydrogel patches (AHPs) that effectively promote the healing of oral ulcers in a rat model. The AHPs are comprised of the quaternary ammonium salt of chitosan, aldehyde-functionalized hyaluronic acid, and a tridentate complex of protocatechualdehyde and Fe3+ (PF). The AHPs exhibit tunable mechanical properties, self-healing ability, and wet adhesion on the oral mucosa. Through controlling the formula of the AHPs, PF released from the AHPs in a temporal manner. We further show that the AHPs have good biocompatibility and the capability to heal oral ulcers rapidly. Both in vitro and in vivo experiments indicate that the PF released from AHPs facilitated ulcer healing by suppressing inflammation, promoting macrophage polarization, enhancing cell proliferation, and inducing epithelial-mesenchymal transition involving inflammation, proliferation, and maturation stages. This study provides insights into the healing of oral ulcers and presents an effective therapeutic biomaterial for the treatment of oral ulcers. By addressing the challenges associated with current clinical treatments for oral ulcers, the development of adhesive hydrogel patches (AHPs) presents an effective approach. These AHPs possess unique properties, such as tunable mechanical characteristics, self-healing ability, and strong adhesion to the mucosa. Through controlled release of protocatechualdehyde-Fe3+ complex, the AHPs facilitate the healing process by suppressing inflammation, promoting cell proliferation, and inducing epithelial-mesenchymal transition. The study not only provides valuable insights into the healing mechanisms of oral ulcers but also introduces a promising therapeutic biomaterial. This work holds significant scientific interest and demonstrates the potential to greatly improve the treatment outcomes and quality of life for individuals suffering from oral ulcers. [Display omitted] [ABSTRACT FROM AUTHOR]

Silica nanoparticles are innovative solutions of surgical glue that can readily adhere to various tissue-like substrates without the need for time-consuming chemical reactions or ultraviolet irradiation. Herein, 10 nm-sized silica nanoparticle (SiNP10) treatment exhibited maximum adhesion strength in the porcine heart tissue model, which was approximately 7.15 times higher than that of the control group of non-treatment. We assessed the effects of silica nanoparticle treatment on in vivo skin wounds by scoring tissue adhesion and inflammation using histological images. Compared to the commercial cyanoacrylate skin adhesive (Dermabond), suppression of inflammatory cytokine levels in the incision wound skin was observed. We further quantified the expression of angiogenic growth factors and connective tissue formation-related proteins. On day 5 after wound closing treatment, the expression levels of PDGF-BB growth factor were significantly higher in SiNP10 treatment (0.64 ± 0.03) compared to Dermabond (0.07 ± 0.05). This stimulated angiogenesis and connective tissue formation in the skin of the incision wound may be associated with the promoting effects of SiNP10 treatment on wound closure and tissue adhesion.

Abdominal adhesions are still among the most common postsurgical peritoneal inflammation-related complications. Adhesion-related disorders are still highly costly and prevalent due to advances in surgical techniques, treatment methods, and various drugs. The present study aimed to investigate the effects of Poly (D,L -lactide-co-glycolide) (PLGA)- polyethylene glycol (PEG6000) Nanofiber + Melatonin on the abdominal adhesion model in rats. For this purpose, PLGA-PEG6000 Nanofiber + Melatonin matrix was fabricated and implanted in an experimental abdominal adhesion model in rats. Our study consisted of an in vitro and an in vivo part. The degradation and release profile of the matrix and Melatonin (Mel) embedded matrix was performed in vitro. In vivo, the procedure was carried out with 18 Wistar male rats. Rats were divided into three groups as follows: Sham, Matrix, and Mel + Matrix, respectively. Consequent to degradation and release profiling in vitro, an experimental adhesion model was created and fabricated pure matrix (2 × 2 cm2), and matrix (2 × 2 cm2, 0.25 mg melatonin/per matrix embedded) was applied to injury area in related groups. Intra-abdominal adhesion scores were determined on post-op 21st day, under general anesthesia. Following, cecum, peritoneal tissue, and adhesive bands were harvested. Macroscopic analysis (severity of adhesion formation), Hematoxlyn&Eosin and Masson's Trichrome staining (for the examination of the levels of infiltration of inflammatory cells, fibrosis, and neovascularization) were performed for the evaluation of the effects of Mel embedded and pure matrix Our results indicated that PLGA-PEG6000 Nanofiber + Melatonin matrix was degraded completely in rats abdominal cavity and significantly reduced adhesion formation compared to other groups macroscopically (p < 0.05). On the other hand, the histopathological analysis indicated that the fabricated matrix reduced inflammatory cell infiltration, fibrosis, and neovascularization levels. [ABSTRACT FROM AUTHOR]

People have grafted plants since antiquity for propagation, to increase yields, and to improve stress tolerance. This cutting and joining of tissues activates an incredible regenerative ability as different plants fuse and grow as one. For over a hundred years, people have studied the scientific basis for how plants graft. Today, new techniques and a deepening knowledge of the molecular basis for graft formation have allowed a range of previously ungraftable combinations to emerge. Here, we review recent developments in our understanding of graft formation, including the attachment and vascular formation steps. We analyze why plants graft and how biotic and abiotic factors influence successful grafting. We also discuss the ability and inability of plants to graft, and how grafting has transformed both horticulture and fundamental plant science. As our knowledge about plant grafting improves, new combinations and techniques will emerge to allow an expanded use of grafting for horticultural applications and to address fundamental research questions. People have grafted plants since antiquity for propagation, to increase yields, and to improve stress tolerance. This review summarizes recent developments in our mechanistic understanding of graft formation and the influence of biotic and abiotic factors on grafting. The ability and inability of plants to graft, and how grafting has transformed both horticulture and fundamental plant science are also discussed. [ABSTRACT FROM AUTHOR]

Type‐A aortic dissection is an acute injury involving the delamination of the aorta at the parts of the aortic media. Aldehyde crosslinker‐containing glues have been used to adhere to the media of the dissected aorta before joining an artificial graft. These glues effectively adhere to the aortic media; however, they show low biocompatibility due to the release of aldehyde compounds. In this study, we report innovative adhesives based on hydrophobically modified Alaska pollock gelatin (hm‐ApGltn) with different alkyl or cholesteryl (Chol) groups that adhere to the media of the dissected aorta by combining hm‐ApGltns with a biocompatible crosslinker, pentaerythritol poly(ethylene glycol) ether tetrasuccinimidyl glutarate. The modification of alkyl or Chol groups contributed to enhanced adhesion strength between porcine aortic media. The adhesion strength increased with increasing modification ratios of alkyl groups from propanoyl to dodecanoyl groups and then decreased at a modification ratio of ~20 mol %. Porcine aortic media adhered using 7.5Chol‐ApGltn adhesive showed stretchability even when expanded and shrunk vertically by 25% at least five times. Hm‐ApGltn adhesives subcutaneously injected into the backs of mice showed no severe inflammation and were degraded during the implantation period. These results indicated that hm‐ApGltn adhesives have potential applications in type‐A aortic dissection. [ABSTRACT FROM AUTHOR]

Intrauterine adhesions (IUA) has become one of the main causes of female infertility. How to effectively prevent postoperative re-adhesion has become a clinical challenge. In this study, a mussel-inspired dual-network hydrogel was proposed for the postoperative anti-adhesion of IUA. First, a calcium alginate/polyacrylamide (CA-PAM) hydrogel was prepared via covalent and Ca2+ cross-linking. Benefiting from abundant phenolic hydroxyl groups, polydopamine (PDA) was introduced to further enhance the adhesion ability and biocompatibility. This CA-PAM hydrogel immersed in 10 mg/mL dopamine solution possessed remarkable mechanical strength (elastic modulus > 5 kPa) and super stretchability (with a breaking elongation of 720%). At the same time, it showed excellent adhesion (more than 6 kPa). Surprisingly, the coagulation index of the hydrogel was 27.27 ± 4.91, demonstrating attractive coagulation performance in vitro and the potential for rapid hemostasis after surgery. [ABSTRACT FROM AUTHOR]

α‐lipoic acid (LA), a coenzyme, has proved to have excellent antioxidant and antibacterial activities; however, its intrinsic hydrophobicity and metastability of polyLA remains a major challenge for the application of LA‐based bulk materials in biomedical field. Herein, a self‐stabilized LA‐based deep eutectic supramolecular polymer (LA‐DESP) adhesive is created by one‐step heating the mixture of LA and sodium α‐lipoate (LA‐Na) (S‐, R‐isomer, racemate) without introducing any exogenous stabilizing molecules. The underlying deep eutectic effect in LA/LA‐Na is unveiled to be originated from the multiple hydrogen bonds between polyLA and polyLA‐Na, which not only prevent polyLA depolymerization but also lower the melting point of LA‐DESP to the near body and pathological temperature. Copolymerization of LA and LA‐Na slows down the dissociation of polyLA‐Na, thus affording sustainable release of bioactive LA‐based small molecules and satisfactory antioxidant and antibacterial functions. Also, the LA‐DESP exhibits fast and tough adhesion to diverse substrates, including wet tissues, relying on its in situ curing property and rich carboxyl groups. The LA‐DESP is explored as a tissue sealant, which can well replace surgical suture to enhance the wound healing of skin incision in a rat model. The unprecedented deep eutectic effect will provide a new strategy for the development of LA‐based bioadhesives. [ABSTRACT FROM AUTHOR]

Thermal wounds are complex and lethal with irregular shapes, risk of infection, slow healing, and large surface area. The mortality rate in patients with infected burns is twice that of non-infected burns. Developing multifunctional skin substitutes to augment the healing rate of infected burns is vital. Herein, we 3D printed a hydrogel scaffold comprising carboxymethyl chitosan (CMCs) and oxidized alginate grafted catechol (O-AlgCat) on a hydrophobic electrospun layer, forming a bilayer skin substitute (BSS). The functional layer (FL) was fabricated by physiochemical crosslinking to ensure favorable biodegradability. The gallium-containing hydrophobic electrospun layer or backing layer (BL) could mimic the epidermis of skin, avoiding fluid penetration and offering antibacterial activity. 3D printed FL contains catechol, gallium, and biologically active platelet rich fibrin (PRF) to adhere to both tissue and BL, show antibacterial activity, encourage angiogenesis, cell growth, and migration. The fabricated bioactive BSS exhibited noticeable adhesive properties (P ≤ 0.05), significant antibacterial activity (P ≤ 0.05), faster clot formation, and the potential to promote proliferation (P ≤ 0.05) and migration (P ≤ 0.05) of L929 cells. Furthermore, the angiogenesis was significantly higher (P ≤ 0.05) when evaluated in vivo and in ovo. The BSS-covered wounds healed faster due to low inflammation and high collagen density. Based on the obtained results, the fabricated bioactive BSS could be an effective treatment for infected burn wounds.

Achieving thermoreversible adhesion between hydrogel and living tissues in a facile way is challenging. Existing strategies bring difficulty to the chemical design and synthesis of hydrogels. Herein, an approach to achieve tough thermoreversible tissue adhesion with hydrogel is proposed, which uses a polymer solution with heat‐induced sol‐gel transition as the interfacial polymer matrix, with no chemical design required for the hydrogel network. When the interfacial polymer matrix is introduced to the interface of the hydrogel and living tissues, it can gelate in situ within the substrate networks under a temperature stimulus, and topologically entangle with the preexisting networks of the substrates, which generates a strong adhesion. By triggering with another temperature stimulus, the newly formed network dissociates to realize an easy detachment. Thermoreversible adhesion is demonstrated between polyacrylamide hydrogel and various porcine tissues as examples, and the mechanism of this adhesion strategy is studied by varying various influence factors. A theoretical model that can fit and predict the effects of different parameters on the adhesion energies is also established. This adhesion strategy based on topological entanglement among a thermoreversible polymer system and the substrates may broaden the achieving methods of thermoreversible tissue adhesion. [ABSTRACT FROM AUTHOR]

Medical devices and human implant materials carry a risk of bacterial infection. Biocompatible and adhesive antibacterial materials that prevent biofilm formation are commonly used to reduce the risk. Herein, a crosslinked chitosan/gelatin (CG) hybrid hydrogel with antibacterial and adhesive properties was developed by introducing berberine hydrochloride (BBR) and adhesive prepolymerized gallic acid (PGA) to the hydrogel. BBR self‐assembles into nanoparticles and imparts AIE function to hydrogels by intermolecular electrostatic interactions and π–π stacking. The hydrogel was used as a stable carrier for BBR. The antibiofilm performance against Escherichia coli and Staphylococcus aureus after light exposure increased from 20% and 30% (CG hydrogel) to 74% and 85% (CGBBRPGA hydrogel), respectively. When used as a photodynamic agent, the hybrid hydrogel exhibited enhanced antibacterial and antibiofilm capabilities against both Gram‐negative (E. coli) and Gram‐positive (S. aureus) bacteria. The CGBBRPGA hydrogel showed strong adhesion to the surfaces of pig skin (9.2 kPa), glass (7.6 kPa), steel sheet (5.8 kPa), and PEEK sheet (5.5 kPa). Furthermore, it exhibits cell adhesion and shows negligible cytotoxicity, which indicates its cytocompatibility. Consequently, the fabricated hybrid hydrogel offers potential applications in biomedicine, particularly in wound dressing and surface modification of medical implants. [ABSTRACT FROM AUTHOR]

Surgical electrodes rely on thermal effect of high-frequency current and are a widely used medical tool for cutting and coagulating biological tissue. However, tissue adhesion on the electrode surface and thermal injury to adjacent tissue are serious problems in surgery that can affect cutting performance. A bionic microstriped structure mimicking a banana leaf was constructed on the electrode via nanosecond laser surface texturing, followed by silanization treatment, to enhance lyophobicity. The effect of initial, simple grid-textured, and bionic electrodes with different wettabilities on tissue adhesion and thermal injury were investigated using horizontal and vertical cutting modes. Results showed that the bionic electrode with high lyophobicity can effectively reduce tissue adhesion mass and thermal injury depth/area compared with the initial electrode. The formation mechanism of adhered tissue was discussed in terms of morphological features, and the potential mechanism for antiadhesion and heat dissipation of the bionic electrode was revealed. Furthermore, we evaluated the influence of groove depth on tissue adhesion and thermal injury and then verified the antiadhesion stability of the bionic electrode. This study demonstrates a promising approach for improving the cutting performance of surgical electrodes. [ABSTRACT FROM AUTHOR]

Medical adhesives that are strong, easy to apply and biocompatible are promising alternatives to sutures and staples in a large variety of surgical and clinical procedures. Despite progress in the development and regulatory approval of adhesives for use in the clinic, adhesion to wet tissue remains challenging. Marine organisms have evolved a diverse set of highly effective wet adhesive approaches that have inspired the design of new medical adhesives. Here we provide an overview of selected marine animals and their chemical and physical adhesion strategies, the state of clinical translation of adhesives inspired by these organisms, and target applications where marine-inspired adhesives can have a significant impact. We will focus on medical adhesive polymers inspired by mussels, sandcastle worms, and cephalopods, emphasize the history of bioinspired medical adhesives from the peer reviewed and patent literature, and explore future directions including overlooked sources of bioinspiration and materials that exploit multiple bioinspired strategies.

Abstract Hydrogel is a polymer network system that can form a hydrophilic three‐dimensional network structure through different cross‐linking methods. In recent years, hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross‐linking mechanisms and functional components. Compared with synthetic hydrogels, natural polymer‐based hydrogels have low biotoxicity, high cell affinity, and great potential for biomedical fields; however, their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements. In recent years, many efforts have been made to solve these issues. In this review, the recent progress in the field of natural polymer‐based adhesive hydrogels is highlighted. The authors first introduce the general design principles for the natural polymer‐based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design. Next, their usages in biomedical applications are summarised, such as wound healing, haemostasis, nerve repair, bone tissue repair, cartilage tissue repair, electronic devices, and other tissue repairs. Finally, the potential challenges of natural polymer‐based adhesive hydrogels are presented.

Development of an injectable hemostatic for treating noncompressible or irregularly shaped bleeding wounds remains a pressing medical need. Herein, we report an injectable thermogelling chitosan/glycerophosphate formulation that enhances gel-forming capacity and wet tissue adherence by incorporation of dihydrocaffeic acid (DHCA). This was found to decrease gelation time by >2 times around 37 °C while increasing hydrogel internal network structure, with its tissue adhesive strength >2 times greater than that of the non-composite hydrogel or previously reported. The thermosensitive hydrogels significantly reduce whole blood coagulation time in vitro and both hemostasis time and blood loss in vivo using rat hepatic hemorrhage and tail amputation models. These improvements are biocompatible, without adversely affecting cell viability, blood components, biodegradability, or introducing notable inflammation, thus enabling injury healing. Moreover, our results displayed the potential of a facile approach to enhance thermogelling and bioadhesion of chitosan-based hydrogels via noncovalent supramolecular mechanisms. [ABSTRACT FROM AUTHOR]

Decellularized matrices can effectively reduce severe immune rejection with their cells and eliminated nucleic acid material and provide specific environments for tissue repair or tissue regeneration. In this study, we prepared acellular cartilage matrix (ACM) powder through the decellularization method and developed ACM hydrogels by physical, chemical, and enzymatic digestion methods. The results demonstrated that the small size group of ACM hydrogels exhibited better gel conditions when the concentration of ACM hydrogels was 30 and 20 mg/mL in 1N HCl through parameter adjustment. The data also confirmed that the ACM hydrogels retained the main components of cartilage: 61.18% of glycosaminoglycan (GAG) and 78.29% of collagen, with 99.61% of its DNA removed compared to samples without the decellularization procedure (set as 100%). Through turbidimetric gelation kinetics, hydrogel rheological property analysis, and hydrogel tissue physical property testing, this study also revealed that increasing hydrogel concentration is helpful for gelation. Besides, the ex vivo test confirmed that a higher concentration of ACM hydrogels had good adhesive properties and could fill in cartilage defects adequately. This study offers useful information for developing and manufacturing ACM hydrogels to serve as potential alternative scaffolds for future cartilage defect treatment. [ABSTRACT FROM AUTHOR]

Recurrent oral ulcers are common oral mucosal lesions that severely reduce patients' quality of life. Commercial mucoadhesive films are easily disrupted due to oral movement and complex wet environments, thus reducing drug utilization and even causing toxic side effects. Herein, we report a mucoadhesive film composed of Ca2+-crosslinked carboxymethylated cellulose nanofibers and alginate, in which two drugs of dexamethasone (DXM) and dyclonine hydrochloride (DYC) are loaded for the treatment of oral ulcers. The wet films have a high Young's modulus of 7.1 ± 2.6 MPa and a large strain of 53.6 ± 9.8 % and adhere to tissue strongly, which allows them to resist the deformation caused by frequent oral movement. The films also have nice durability against water and excellent biocompatibility. Moreover, the drug release was controlled at different rates. The fast release of DYC facilitates the quick relief of pain, while the slow release of DXM benefits the long-term treatment of wounds. Finally, the animal experiment demonstrates the films displayed excellent therapeutic efficacy in healing oral ulcers. [Display omitted] [ABSTRACT FROM AUTHOR]

Intrauterine adhesions (IUA) has become one of the main causes of female infertility. How to effectively prevent postoperative re-adhesion has become a clinical challenge. In this study, a mussel-inspired dual-network hydrogel was proposed for the postoperative anti-adhesion of IUA. First, a calcium alginate/polyacrylamide (CA-PAM) hydrogel was prepared via covalent and Ca2+ cross-linking. Benefiting from abundant phenolic hydroxyl groups, polydopamine (PDA) was introduced to further enhance the adhesion ability and biocompatibility. This CA-PAM hydrogel immersed in 10 mg/mL dopamine solution possessed remarkable mechanical strength (elastic modulus > 5 kPa) and super stretchability (with a breaking elongation of 720%). At the same time, it showed excellent adhesion (more than 6 kPa). Surprisingly, the coagulation index of the hydrogel was 27.27 ± 4.91, demonstrating attractive coagulation performance in vitro and the potential for rapid hemostasis after surgery.

Wounds on stretchable parts of the human body cause prolonged suffering and involve more severe healing processes than wounds on stationary parts. However, they have received insufficient attention compared with other types of chronic wounds. In this study, a novel supramolecular gelatin (GT) hydrogel composed of GT-graft-aniline tetramer and quaternized chitosan was presented. The hydrogel was crosslinked by monoaldehyde β-cyclodextrin via host—guest interaction and dynamic Schiff base and was free from permanent covalent bonds, heavy metals, and oxidants. Given its dynamic feature, the hydrogel exhibited flexibility, self-healing, and tissue adhesiveness and well adapted to motion wounds. Moreover, the hydrogel was bioactive with conductivity, antioxidant property, hemostatic effect, antibacterial, and photothermal effect (the killing ratio for methicillin-resistant Staphylococcus aureus (MRSA) was higher than 99.8% after 5 min of near-infrared irradiation) and exhibited on-demand removability. In the full-thickness MRSA-infected motional wound healing experiment, this novel hydrogel exhibited a significantly enhanced wound healing efficacy with a fast wound closure ratio (about 99.0% for 14 days), mild inflammatory response, high level of collagen deposition, and enhanced re-epithelialization by downregulating interleukin-6 and CD68 and upregulating vascular endothelial growth factor. The results indicated that this hydrogel has great potential in wound healing and skin tissue engineering and serves as an inspiration for the design of supramolecular biomaterials. [ABSTRACT FROM AUTHOR]

Glue-type bio-adhesives are in high demand for many applications, including hemostasis, wound closure, and integration of bioelectronic devices, due to their injectable ability and in situ adhesion. However, most glue-type bio-adhesives cannot be used for short-term tissue adhesion due to their weak instant cohesion. Here, we show a novel glue-type bio-adhesive based on the phase separation of proteins and polysaccharides by functionalizing polysaccharides with dopa. The bio-adhesive exhibits increased adhesion performance and enhanced phase separation behaviors. Because of the cohesion from phase separation and adhesion from dopa, the bio-adhesive shows excellent instant and long-term adhesion performance for both organic and inorganic substrates. The long-term adhesion strength of the bio-glue on wet tissues reached 1.48 MPa (shear strength), while the interfacial toughness reached ~880 J m−2. Due to the unique phase separation behaviors, the bio-glue can even work normally in aqueous environments. At last, the feasibility of this glue-type bio-adhesive in the adhesion of various visceral tissues in vitro was demonstrated to have excellent biocompatibility. Given the convenience of application, biocompatibility, and robust bio-adhesion, we anticipate the bio-glue may find broad biomedical and clinical applications. [ABSTRACT FROM AUTHOR]

Mechanically regulated wound dressings require a rational combination of contraction and adhesion functions as well as balancing exudate-induced swelling issues. However, many of the reported dressings face the dilemma of impaired function and impeded wound self-contraction due to fluid-absorbing swelling. In this study, inspired by the tree ring, a core-ring structured hydrogel dressing capable of mechanical modulation is designed, and prepare it using a simple two-step photopolymerization process. The core covers the center of the wound, contracts spontaneously at body temperature to generate a contractile force of 3.4 kPa, and resists swelling. Meanwhile, the ring adheres to the normal epidermis around the wound and transfers the contraction stress to the wound edge. The integration of a functionally independent core and ring ultimately achieves effective wound traction and avoids dressing swelling. In murine and porcine skin wound-healing models, this hydrogel with a closely connected core and ring promotes healing by accelerating epidermal closure (50% closure in mouse skin on day 2, 85% closure in pig skin on day 8), collagen deposition, vascular maturation, and extracellular matrix remodeling. These results can guide further research on mechanical force modulation in wound healing, with the potential for clinical translation., (© 2024 Wiley‐VCH GmbH.)

Flexible sensors have potential applications in the fields of wearable devices, implantable devices, and electronic skin, etc. Polymer hydrogels have biomimetic mechanical properties and biocompatibility, and thus are widely recognized as promising candidate materials for biomimetic flexible devices. Conductive hydrogels, including electron conductive and ion conductive hydrogels, have been widely developed as fundamental materials for flexible sensors. The mechanical properties and sensory performance can be conveniently manipulated by designing the network structures of hydrogels to meet the demands of diverse applications. Linear sensitivity, wide working range, linearity, low limit of detection and stability are pursued by designing not only the network structure, but also the device configurations and microstructures. Moreover, the device-tissue interface is critical for implantable applications for monitoring the motions and health of tissues and organs. This review systematically accounts the latest progress in the field of hydrogel sensors including our studies on tough conductive hydrogel sensors, paying special attention to structure-performance relationship, hydrogel-tissue adhesion, and application for human organ motion monitoring. Interpenetrating conductive/hydrophilic networks provide not only high strength and toughness, but also low percolation conductivity, high conductivity and linear sensitivity over a broad working range. Ion conductive hydrogels based on zwitterionic polymers show very high stretchability and ion conductivity, self healing, and sensitivity, primarily attributed to the dipole-dipole interaction and ion conduction channels. Such zwitterionic sensors are adhesive to biotissues, and enable real-time monitoring of organ motions. This review aims to inspire new ideas to develop novel high performance hydrogel sensors, shed new insights into mechanisms behind the sensory performances, and boost hydrogel devices toward practical applications. Major challenges and future opportunities in this rapidly developing field are outlooked. [ABSTRACT FROM AUTHOR]

Hydrogel is a polymer network system that can form a hydrophilic three‐dimensional network structure through different cross‐linking methods. In recent years, hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross‐linking mechanisms and functional components. Compared with synthetic hydrogels, natural polymer‐based hydrogels have low biotoxicity, high cell affinity, and great potential for biomedical fields; however, their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements. In recent years, many efforts have been made to solve these issues. In this review, the recent progress in the field of natural polymer‐based adhesive hydrogels is highlighted. The authors first introduce the general design principles for the natural polymer‐based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design. Next, their usages in biomedical applications are summarised, such as wound healing, haemostasis, nerve repair, bone tissue repair, cartilage tissue repair, electronic devices, and other tissue repairs. Finally, the potential challenges of natural polymer‐based adhesive hydrogels are presented. [ABSTRACT FROM AUTHOR]

The stable adhesion of hydrogel-based bioadhesives with tissue-matchable mechanical properties in biological environments remains a significant challenge. In this work, we propose a polyethyleneimine-polyacrylic acid (PEI-PAA, PEA) double-network polyelectrolyte hydrogel with swelling resistant capacity and tunable mechanical properties via one-step UV-initiated polymerization. Driven by electrostatic interactions and polymer-chain entanglement, this PEA hydrogel displays a distinctive microphase separation behavior, which facilitates a wide tunability in mechanical properties. Specifically, the modulus varies from 0.4 MPa to 106 MPa, and the toughness ranges from 1479 kJ/m3 to 7641 kJ/m3, respectively. Besides, the microphase separation endows PEA hydrogel with notable anti-swelling properties in saline, TBS buffer, and blood, leading to consistent adhesion to diverse moist tissues. We further demonstrate that our PEA hydrogels provide matchable mechanical properties and long-lasting adhesion to rat skin and arteries, which promote skin injury healing and effectively halt artery rupture bleeding in vivo. This work presents a straightforward method to generate non-swelling hydrogels and offers novel insight into the development of bioadhesives to meet diverse mechanical requirements. • A facile method is developed to prepare polyelectrolyte hydrogels with ultrahigh mechanical tunability. • Microphase separation structure endows hydrogels with excellent mechanical and anti-swelling performances. •The tissue-matchable hydrogels exhibit instant and stable adhesion for versatile wound healing. [ABSTRACT FROM AUTHOR]

The microbiota colonizing in the uterine cavity has been demonstrated by next -generation sequencing and microbiome technology in recent years. The changes of uterine microbiota are connected not only with physiological factors, but also with female reproductive healthy diseases. However, the core composition of uterine microbiota and the relationship between the host and the microbiota still remain unknown. The disorder of uterine microbiota could be related to the pathogenesis and pathophysiology of chronic endometritis, recurrent implantation failure, endometriosis and intrauterine adhesion, etc. However, there is not a consensus on the unified protocol to assess the dysbiosis of uterine microbiota and the optimal treatment protocol to adjust above dysbiosis. To some extent, probiotics or prebiotics using in vagina can assist to treat the dysbiosis of uterine microbiota and to improve the pregnancy outcome. In this review, we discussed the uterine microbiota and its relationship with female reproductive health. [ABSTRACT FROM AUTHOR]

Following removal of hides and viscera during beef processing, carcasses are inspected for tissue adhesions that can affect meat quality or harbor bacteria. Carcasses with pleural or abdominal adhesions may be diverted from the production line for manual excision and then returned to the line. No published data indicate whether adhesion excision is associated with bacterial contamination. Therefore, our objective was to determine the presence and concentration of generic Escherichia coli and non–E. coli coliforms from the internal and external surfaces of carcasses that were, or were not, diverted for adhesion excision. During 9 processing days over a 4-month period in a large commercial beef processing facility, 1,738 carcass sponge samples from 2,730 cm2 areas on both the internal and the external surfaces of carcasses with and without tissue adhesions were collected. Coliforms and E. coli were cultured and enumerated using Petrifilm procedures, and data were analyzed with mixed models. Coliforms were present at higher concentrations than E. coli, and prevalence and mean log concentrations of both coliforms and E. coli were significantly higher for samples from the external than from the internal surfaces of carcasses. However, differences in prevalence and concentration of coliforms between external and internal surfaces varied significantly based on whether carcasses had adhesions excised. The difference was greatest for coliforms present on the external (2.06 log CFU/100 cm2) versus the internal (0.93 log CFU/100 cm2) carcass surfaces without adhesions, whereas the difference in concentrations from the external (1.80 log CFU/100 cm2) and the internal (1.31 log CFU/100 cm2) surfaces of carcasses with adhesions was not as large. These results indicate that surveillance of carcass bacteria may be affected by whether the external versus the internal surfaces are sampled and whether carcasses are diverted for excision of adhesions. [ABSTRACT FROM AUTHOR]

In spite of the great progress of wound healing materials, the development of dressing with moisture permeability, stretchable capability, and adhesive performance remains a huge challenge. In this study, gelatin-dopamine (GT-DA) nanofiber membrane was prepared by introducing dopamine (DA) into gelatin (GT) via electrospinning followed by in-situ reaction. The effects of DA dosage, crosslinking condition and crosslinking time on the mechanical properties of the fiber membrane were studied systematically. The resultant GT-DA nanofibrous hydrogels exhibited integrated stress strength of 1.96 MPa, good water absorption of 700%, and water vapor transmission (WVT: 4.3 kg m−2d−1), which were superior than those of Mepiform®, a commercial adhesive silicone dressing. In addition, Fe3+ were introduced into one side of the nanofiber membrane. A stronger adhesion strength of 2.5 KPa on the porcine skin, which was 1.6 times higher than that of Mepiform® was achieved. Our research showed that the prepared nanofibrous hydrogel has potential as wound dressing and could be used in post-traumatic tissue healing engineering. This work presented a type of breathable, stretchable and adhesive nanofibrous hydrogels, which would ensure the stable attachment on wounds during movement as a wound healing material.

Herein, Polydopamine-modified microgels and microgels incorporated with superficial epoxy groups were synthesized and applied as precursors for the fabrication of four granular hydrogels. To enhance the tissue adhesiveness, a ternary deep eutectic solvent was synthesized to activate the muscle amine functional groups facilitating the formation of robust NC bonds at ambient conditions. At a certain shear rate of 10 s -1 , hydrogel DMG displayed a viscosity of 9×10 3  Pa/s, representing the highest complex viscosity among the tested hydrogels primarily driven by quinone groups in PDA which enhanced reversible interactions, thereby increasing particle cohesion. Moreover, the intersection point escalating from about 4×10 3 to approximately 9×10 4 as the concentration of DMG increased from 0 % (for MG) to 70% (7D3MG) by weight. There was a decrease in adhesion strength from 0.45 ± 0.08 N in MG to 0.39 ± 0.16 N, 0.35± 0.18 N, and 0.33 ± 0.15 N for 3D7MG, 7D3MG, and DMG respectively, suggesting that MG was capable of forming numerous covalent bonds, thereby enhancing its adhesion to the substrate. The type of eutectic mixture affected the electrical conductivity and a very important point was the changes in resistance value with time. For MG catalyzed by [DES] AZG , the resistance increased only by 1.3 % (from 3.37 to 3.81 kΩ) at day 3 and 37.09 % (from 3.37 to 4.62 kΩ) at day 5. The 3D7MG hydrogel exhibited superior therapeutic efficacy toward diabetic wound regeneration. The proliferation index value for 3D7MG-[DES] AZG and 3D7MG-[DES] AG were calculated 42.3 % and 58.6 %, respectively, while the control group exhibited a lower value of 37.8 %., Competing Interests: Declaration of competing interest The authors declare they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Developing multifunctional self-healing hydrogels as wound dressings, including strong tissue adhesion, spray film-forming ability, and excellent bioactivity, are highly desired for full-thickness skin wound healing applications. In this study, chondroitin sulfate (CSA) was firstly oxidized to aldehyde-based chondroitin sulfate (OHC-CSA), and then dopamine (DA) was grafted onto OHC-CSA to form OHC-CSA-DA. Thereafter, the OHC-CSA-DA and carboxymethyl chitosan (COOH-CS) based hydrogel (CSA-DA-CS) was successfully fabricated through integrating enzymatic crosslinking, Schiff base and hydrogen bonding interactions. The optimum adhesive strength of the hydrogel was obtained by an orthogonal design when the concentrations of polymer, HRP enzyme, and H2O2 were 30 mg/mL, 0.24 U/mL, and 0.00085%, respectively. This novel hydrogel showed rapid self-healing performance, robust mechanical strength and strong adhesion, spray film-forming ability, hemostatic property, antibacterial property and good biocompatibility, which are beneficial to function as a wound dressing. Besides, the addition of mesenchymal stem cell-conditioned medium (CM) can further improve the biocompatibility and wound repair ability of the hydrogel.Therefore, this novel hydrogel is an outstanding wound dressing candidate for full-thickness wound healing.

Underwater electrocardiography (ECG) monitoring, which can monitor cardiac autonomic changes and arrhythmias during diving, is essential for sports management and healthcare. However, it is crucial yet rather challenging to achieve ECG monitoring in an aquatic environment because the interface electrodes may lose their functionality underwater. Here, an ionogel with tailorable mechanical properties is prepared by a facile one‐step polymerization and used as water‐resistant electrode. The Young's modulus and strain at break of the ionogel can be modulated in the range of 0.22–337 MPa and 349 to >10 000%, respectively. The hydrophobic polymer networks inside the ionogel endow this ionogel with excellent stability, adhesion, and self‐healing ability underwater. The ionic conductivity imparted by the free ionic groups inside the ionogel allows the ionogel to detect and transmit physiological electrical signals. Compared with commercial gel electrodes, this ionogel electrode demonstrates better adhesion ability, conductivity, and stability underwater. The ionogel electrode can collect real‐time ECG signals effectively both in the air and underwater, and the data can be used to warn users of the potential risk of a heart attack. [ABSTRACT FROM AUTHOR]

Acute wounds often cause overdeveloped inflammation, which can adversely affect wound healing. Wound dressing has been widely used, but it is still challenging to achieve an effective anti-inflammation treatment due to the complex wet environment of the wounds. Here, we proposed a wound sealant, tannic acid-silk fibroin-diclofenac potassium (TA-SF-DP, TSD) hydrogels. And evaluated their wet-adhesion performance and the potency on inflammation regulation through comprehensive mechanical tests and molecular biology research. The TSD hydrogels exhibited an outstanding wet-adhesion property to porcine soft tissues even in blood (up to (38.6 ± 4.6) kPa) and strong hemostatic ability in rat tail truncation model ((reduced hemostasis time from (685 ± 55) s to (160 ± 72) s and reduced blood loss from (0.59 ± 0.07) g to (0.06 ± 0.03) g compared with the gauze group). Simultaneously, the hydrogels showed satisfactory anti-inflammatory effects (sustained reduction of inflammation at 6 h and 24 h, generally the peak and persistent state of severe postoperative reaction, respectively), which works by releasing non-steroidal anti-inflammatory drug DP conforming to physiological needs. Combined with the wet adhesion, anti-inflammatory property and remarkable biocompatibility, the TSD hydrogels have the potential to be a clinical wound sealant to manage acute wounds.

Material advances in soft bioelectronics, particularly those based on stretchable nanocomposites─functional nanomaterials embedded in viscoelastic polymers with irreversible or reversible bonds─have driven significant progress in translational medical device research. The unique mechanical properties inherent in the stretchable nanocomposites enable stiffness matching between tissue and device, as well as its spontaneous mechanical adaptation to in vivo environments, minimizing undesired mechanical stress and inflammation responses. Furthermore, these properties allow percolative networks of conducting fillers in the nanocomposites to be sustained even under repetitive tensile/compressive stresses, leading to stable tissue-device interfacing. Here, we present an in-depth review of materials strategies, fabrication/integration techniques, device designs, applications, and translational opportunities of nanocomposite-based soft bioelectronics, which feature intrinsic stretchability, self-healability, tissue adhesion, and/or syringe injectability. Among many, applications to brain, heart, and peripheral nerves are predominantly discussed, and translational studies in certain domains such as neuromuscular and cardiovascular engineering are particularly highlighted.

Existing artificial periostea face many challenges, including difficult-to-replicate anisotropy in mechanics and structure, poor tissue adhesion, and neglected synergistic angiogenesis and osteogenesis. Here, inspired by natural wood (NW), a wood-derived elastic artificial periosteum is developed to mimic the structure and functions of natural periosteum, which combines an elastic wood (EW) skeleton, a polydopamine (PDA) binder layer, and layer-by-layer (LBL) biofunctional layers. Specifically, EW derived from NW is utilized as the anisotropic skeleton of artificial periosteum to guide cell directional behaviors, moreover, it also shows a similar elastic modulus and flexibility to natural periosteum. To further enhance its synergistic angiogenesis and osteogenesis, surface LBL biofunctional layers are designed to serve as spatiotemporal release platforms to achieve sequential and long-term release of pamidronate disodium (PDS) and deferoxamine (DFO), which are pre-encapsulated in chitosan (CS) and hyaluronic acid (HA) solutions, respectively. Furthermore, the combined effect of PDA coating and LBL biofunctional layers enables the periosteum to tightly adhere to damaged bone tissue. More importantly, this novel artificial periosteum can boost angiogenesis and bone formation in vitro and in vivo. This study opens up a new path for biomimetic design of artificial periosteum, and provides a feasible clinical strategy for bone repair., (© 2024 Wiley‐VCH GmbH.)

Decellularized matrices can effectively reduce severe immune rejection with their cells and eliminated nucleic acid material and provide specific environments for tissue repair or tissue regeneration. In this study, we prepared acellular cartilage matrix (ACM) powder through the decellularization method and developed ACM hydrogels by physical, chemical, and enzymatic digestion methods. The results demonstrated that the small size group of ACM hydrogels exhibited better gel conditions when the concentration of ACM hydrogels was 30 and 20 mg/mL in 1N HCl through parameter adjustment. The data also confirmed that the ACM hydrogels retained the main components of cartilage: 61.18% of glycosaminoglycan (GAG) and 78.29% of collagen, with 99.61% of its DNA removed compared to samples without the decellularization procedure (set as 100%). Through turbidimetric gelation kinetics, hydrogel rheological property analysis, and hydrogel tissue physical property testing, this study also revealed that increasing hydrogel concentration is helpful for gelation. Besides, the ex vivo test confirmed that a higher concentration of ACM hydrogels had good adhesive properties and could fill in cartilage defects adequately. This study offers useful information for developing and manufacturing ACM hydrogels to serve as potential alternative scaffolds for future cartilage defect treatment.

In recent years, the hydrogel-based tissue adhesives have been extensively investigated for their excellent biocompatibility and the ability to be administered directly within the adherent tissue. To meet the requirement for more controllable release in various physiological settings, the components of hydrogel adhesive should be more precisely tailored. In this work, the POSS-ace-PEG hydrogel adhesive was fabricated with the polyacetal dendrimer G1'-[NH3Cl]16 and poly(ethylene glycol) succinimidyl carbonate (PEG-SC) due to the regular peripheral amino structure of G1'-[NH3Cl]16. Rheological and adhesion tests demonstrated that the hydrogel adhesive had good mechanical and adhesive properties, which could effectively adhere to the pigskin and severed nerves. Moreover, the tissue adhesive exhibited good stability under neutral conditions and the rapid degradation under acidic conditions, allowing for the release of doxycycline hydrochloride (DOX) drug in response to pH. Together, these results suggested that the POSS-ace-PEG adhesive had the potential to provide an alternative to tissue adhesives for applications in pathological environments (inflammation, tumors, etc.). [ABSTRACT FROM AUTHOR]

Injectable polymers (IPs) exhibiting in situ hydrogel formation have attracted attention as vascular embolization and postoperative adhesion prevention materials. While utilizing hydrogels for such purposes, it is essential to ensure that they have appropriate and controllable tissue adhesion property, as it is crucial for them to not detach from their deposited location in the blood vessel or abdominal cavity. Additionally, it is important to maintain gel state in vivo for the desired period at such locations, where large amounts of body fluid exist. We had previously reported on a biodegradable IP system exhibiting temperature-responsive gelation and subsequent covalent cross-link formation. We had utilized triblock copolymers of aliphatic polyester and poly(ethylene glycol) (tri-PCGs) and its derivative containing acrylate group at the termini (tri-PCG-Acryl), exhibiting a longer and more controllable duration time of the gel state. In this study, the introduction of aldehyde groups by the addition of aldehyde-modified Pluronic (PL-CHO) was performed for conferring controllable and appropriate tissue adhesive properties on these IP systems. The IP systems containing PL-CHO, which were not covalently incorporated into the hydrogel network, exhibited tissue adhesive properties through Schiff base formation. The adhesion strength could be controlled by the amount of PL-CHO added. The IP system showed good vascular embolization performance and pressure resistance in the blood vessels. The IP hydrogel remained at the administration site in the abdominal space for 2 days and displayed effective adhesion prevention performance. Injectable polymers (IPs), which exhibit in situ hydrogel formation, are expected to be utilized as vascular embolization and postoperative adhesion prevention materials. The tissue adhesion properties of hydrogels are important for such applications. We succeeded in conferring tissue adhesion properties onto a previously reported IP system by mixing it with Pluronic modified with aldehyde groups (PL-CHO). The aldehyde groups allowed for the formation of Schiff bases at the tissue surfaces. The tissue adhesion property could be conveniently controlled by altering the amount of PL-CHO. We revealed that the in vitro embolization properties of IPs in blood vessels could be substantially improved by mixing with PL-CHO. The IP system containing PL-CHO also exhibited good in vivo performance for postoperative adhesion prevention. [Display omitted] [ABSTRACT FROM AUTHOR]

Full‐thickness skin injuries have always been an intricate problem in clinical treatment. The application of biomaterials provides an artificial matrix for the recruitment of cells and deposition of extracellular matrix to accelerate wound healing. For the recovery of full‐thickness skin defects, the double cross‐linking of MgO‐catechol and Schiff's base bonds are used as part of the gel‐forming mechanism, and a bio‐multifunctional hydrogel (CCOD‐MgO) is prepared by adding MgO to catechol‐modified chitosan (CHI‐C) and oxidized dextran (ODex). The CCOD‐MgO demonstrates high tissue adhesion, excellent self‐repairing, hemostasis function, and low swelling rate. With the addition of MgO and catechol chelation, the adhesion strength of CCOD‐MgO is about 35 kpa, which is much greater than fibrin glue. Moreover, the CCOD‐MgO has better antibacterial properties than CHI‐C/ODex hydrogel (CCOD) due to the synergy of chitosan and MgO in vitro. Accordingly, the CCOD‐MgO can protect the wounds from infection and accelerate the healing speed of the epidermis in full‐thickness cutaneous defect and burn model in vivo. These results demonstrate that the CCOD‐MgO would be a promising therapeutic strategy in full‐thickness skin injuries for clinical therapies. [ABSTRACT FROM AUTHOR]

Existing artificial periostea faces difficulty in supporting the entire bone repair cycle due to the absence of adhesion‐centric design and effective cell manipulation, leading to poor inhibition of soft tissue infiltration and induction of osteogenesis and angiogenesis. Here, a Janus periosteum with interior surface adhesion and exterior anatomical patterns to mimic the structure and function of natural periosteum is presented. Photo‐crosslinkable polymers are employed to replicate the exterior anisotropic surface structured microgrooves for cell fate manipulation and assemble gecko‐inspired fibrillar setae arrays for interior surface adhesion. To further bolster its underwater adhesiveness, mussel‐inspired poly (dopamine methacrylamide‐co‐hydroxyethyl methacrylate) (PDMH) is coated onto the periosteum surfaces. This periosteum presents adhesiveness with strong shear and normal adhesion in both dry and wet conditions due to the coordinated interactions of micro setae arrays and PDMH coating; it also boasts effective cell modulation for enhanced synchronous osteogenesis and angiogenesis, without the aid of growth factors. Moreover, the Janus periosteum is found to enhance bone regeneration in vivo with increased new bone formation and neovascularization. It is envisioned that this Janus periosteum will be able to streamline bone fracture surgical repair as a rapidly adhesive, low‐maintenance yet robust bandage to significantly cut down the healing phase. [ABSTRACT FROM AUTHOR]

Plant grafting is generally performed between closely related species. Recently, we have discovered that Nicotiana species of Solanaceae show the ability to graft with distantly related plant species beyond the family. Graft adhesion with diverse angiosperms by Nicotiana species was probably facilitated by the secretion of a subclade of ß-1,4-glucanases. The capability of interfamily grafting was also found in the model Orobanchaceae hemiparasitic plant, Phtheirospermum japonicum, which naturally invades to the tissues of host plants of different families. Transcriptome analysis indicated that the same clade of ß-1,4-glucanase plays an important role in plant parasitism. Thus, the tissue adhesion between distant plant species occurs both naturally and artificially. Here, we further observed the capability of interfamily grafting in the stem holoparasitic genus, Cuscuta. These findings indicate that the natural process of tissue adhesion is a potential clue to improve plant-grafting techniques.

Glue-type bio-adhesives are in high demand for many applications, including hemostasis, wound closure, and integration of bioelectronic devices, due to their injectable ability and in situ adhesion. However, most glue-type bio-adhesives cannot be used for short-term tissue adhesion due to their weak instant cohesion. Here, we show a novel glue-type bio-adhesive based on the phase separation of proteins and polysaccharides by functionalizing polysaccharides with dopa. The bio-adhesive exhibits increased adhesion performance and enhanced phase separation behaviors. Because of the cohesion from phase separation and adhesion from dopa, the bio-adhesive shows excellent instant and long-term adhesion performance for both organic and inorganic substrates. The long-term adhesion strength of the bio-glue on wet tissues reached 1.48 MPa (shear strength), while the interfacial toughness reached ~880 J m−2. Due to the unique phase separation behaviors, the bio-glue can even work normally in aqueous environments. At last, the feasibility of this glue-type bio-adhesive in the adhesion of various visceral tissues in vitro was demonstrated to have excellent biocompatibility. Given the convenience of application, biocompatibility, and robust bio-adhesion, we anticipate the bio-glue may find broad biomedical and clinical applications.

Bioadhesive is a substitute or complement to traditional surgical sutures for promoting wound closure. In this study, we developed a simply formulated tough bioadhesive based on the co-assembly of ε-poly-L-lysine (ε-PLL) and hyaluronan (HA) using a vacuum drying strategy. The formula of the bioadhesive was optimized by adjusting the solute content and the ε-PLL/HA mass ratio. The intermolecular interactions were characterized using infrared spectroscopy. Rheological behaviors, including apparent viscosity (cohesion) and fluid types of the adhesives, were investigated. The ε-PLL/HA bioadhesive demonstrated strong adhesion to wet tissues and other abiotic substrates. [Display omitted] • A simply formulated tough bioadhesive is created through the co-assembly of ε-PLL and HA. • The bioadhesive can effectively maintain viscosity and demonstrate shear-thinning properties. • The bioadhesive exhibits a strong capability to bond wet tissues with robust adhesion strength. [ABSTRACT FROM AUTHOR]

Abstract Background Fractures of the orbital wall are mainly caused by traffic accidents, assaults, and falls and generally occur in men aged between 20 and 40 years. Complications that may occur after an orbital fracture include diplopia and decreased visual acuity due to changes in orbital volume, ocular depression due to changes in orbital floor height, and exophthalmos. If surgery is delayed too long, tissue adhesion will occur, making it difficult to improve ophthalmologic symptoms. Thus, early diagnosis and treatment are important. Fractures of the superior orbital wall are often accompanied by skull fractures. Most of these patients are unable to perform an early ocular evaluation due to neurosurgery and treatment. These patients are more likely to show tissue adhesion, making it difficult to properly dissect the tissue for wall reconstruction during surgery. Case presentation This report details a case of superior orbital wall reconstruction using superior orbital rim osteotomy in a patient with a superior orbital wall fracture involving severe tissue adhesion. Three months after reconstruction, there were no significant complications. Conclusion In a patient with a superior orbital wall fracture, our procedure is helpful in securing the visual field and in delamination of the surrounding tissue.

Tissue adhesion and thermal injury bring great risk to electrosurgical cutting. The aim of this study is to propose a novel ultrasonic vibration-assisted (UV-A) electrosurgical cutting system to minimize tissue adhesion and thermal injury, and thereby improve the cutting performance. To this end, the ultrasonic vibration technology was integrated into electrosurgical cutting to develop a UV-A electrosurgical cutting system. Finite element (FE) simulations and experiments were performed to verify the effectiveness of the proposed UV-A technology. An orthogonal UV-A electrosurgical cutting FE model was developed using the Comsol Multiphysics software. Subsequently, the effect of UV-A on the temperature distribution and thermal injury during the electrosurgical cutting process was investigated. The FE simulation results indicated that UV-A can reduce the temperature distribution and thermal injury area. The experimental results demonstrated that the temperature and injury depth under UV-A electrosurgical cutting were respectively decreased by approximately 40% and 30% compared with that without UV-A. The experimental results agreed well with the FE simulation results. Hence, it is concluded that UV-A electrosurgical cutting can be a novel promising and practical technology for reducing tissue adhesion and thermal injury.

Bone bleeding and bone defects arising from trauma or bone tumor resection pose a great threat to patients and they are challenging problems to orthopedic surgeons. Traditional hemostatic materials are not suitable for bone fractures where compression cannot be applied, neither are they effective during surgeries where large amounts of body fluids prevent them from adhering to the large and irregular bone wound sites. This research introduces a catechol‐conjugated chitosan (CHI‐C) multi‐functional hydrogel with adhesion, self‐healing, cytocompatibility, hemocompatibility, and blood cell coagulation capacity. The hydrogel can be injected into internal and irregular bleeding sites and bone defective areas, and then rapidly self‐heals (within 2 min) to an integrated hydrogel that fully fills the defective sites and strongly sticks to bleeding areas in the presence of body fluids during surgery. In vivo experiments using a rabbit ilium bone defect model demonstrate quick hemostasis after the hydrogel is applied and the blood loss is only ¼ compared to the untreated injuries. In addition, the bone regeneration is not interfered by the hydrogel and the bone defect is no longer visible with disappearance of the hydrogel after 4 weeks. This multi‐functional hydrogel is potentially valuable for clinical applications towards tissue adhesion, hemostasis, and bone regeneration. [ABSTRACT FROM AUTHOR]

Essentially, intrauterine adhesion (IUA) is a endometrial damage and fibrosis due to injury, infection and other factors. The pathogenesis of IUA includes epithelial -mesenchymal transformation, excessive inflammatory response, dysangiogenesis, low estrogen status and endometrial stem cell loss. The clinical treatments at present, such as hysteroscopic adhesion separation, hormone therapy, physical barrier implantation, etc., cannot effectively improve the IUA condition of patients with moderate to severe IUA, and cannot also prevent the recurrence of adhesion. In recent years, mesenchymal stem cells have showed the great potential in tissue repair and regenerative medicine. At present, the main stem cells used in IUA study are endometrial mesenchymal stem cell, bone marrow mesenchymal stem cell, fat mesenchymal stem cell and gestational appendage derived mesenchymal stem cell. Through immune regulation, differentiation and paracrine, the mesenchymal stem cell can rebuild endometrial tissue and improve endometrial function, which is a new hope for patients with intrauterine adhesion. [ABSTRACT FROM AUTHOR]

Tissue adhesives have been developed for sealing tissue damaged in surgery. Among these, sheet-type adhesives require a relatively long time to adhere to biological tissue under wet conditions. To address this clinical problem, we fabricated a tissue-adhesive fiber sheet (AdFS) based on decanyl group (C10) modified Alaska pollock-derived gelatin (C10-ApGltn) using electrospinning. Ultraviolet (UV) irradiation of the AdFS was performed to increase the affinity between the AdFS and wet biological tissue by introducing hydrophilic functional groups. The UV irradiated AdFS (UV-C10-AdFS) strongly adhered to porcine pleura within 2 min under wet conditions and showed higher burst strength compared with the original ApGltn (Org-ApGltn) sheet. Hematoxylin-eosin stained sections revealed that a dense UV-C10-AdFS layer remained on the surface of the porcine pleura even after burst strength measurement. Moreover, UV-C10-AdFS has excellent cytocompatibility and efficiently supports the growth of L929 cells. UV-C10-AdFS is a promising adhesive material for sealing wet biological tissue. [ABSTRACT FROM AUTHOR]

To satisfy the ever‐accelerated demands for advanced engineering biomaterials with excellent physicochemical properties, injectable and recoverable dual‐network (DN) hydrogels based on poly(l‐lysine)‐graft‐4‐hydroxyphenylacetic acid (PLL‐g‐HPA) and Aga are constructed by simply mixing PLL‐g‐HPA/HRP and PLL‐g‐HPA/H2O2 in Aga through enzyme‐catalyzed cross‐linkage of PLL‐g‐HPA and temperature‐adjusted sol‐gel transition of Aga. The recoverable and injectable performances of hydrogels are attributed to the reversible sol‐gel transitional feature of Aga and enzymatically cross‐linked reaction of PLL‐g‐HPA. DN hydrogels have fast and adjusted gelation time, connective pore structure, superior formability, and good biocompatibility. The helically structural Aga network endows the hydrogels with good mechanical strength and superior stability in extreme condition. Schiff‐base effect between amino in skin tissues and carbonyl formed by the oxidation of phenol groups in hydrogel imparts the hydrogels to promising tissue attachment. Bursting pressure assay illustrates that the bursting pressure (34.5 ± 2.4 kPa) for 13.6% DN hydrogel is much higher than arterial blood pressure (16 kPa). The incorporated cationic PLL‐g‐HPA gives the hydrogels remarkable antibacterial ability, which effectively prevents the bacterial infection. In conclusion, the DN hydrogel with good cytocompatibility, inherently antibacterial ability, tissue adhesion, and excellent stability in extreme environment is probably able to become a promising candidate as potential wound dressings. [ABSTRACT FROM AUTHOR]