In situ forming injectable γ-poly(glutamic acid)/PEG adhesive hydrogels for hemorrhage control

A mitochondria-targeting heptamethine cyanine-chlorambucil formulated polymeric nanoparticle to potentiate native tumor chemotherapeutic efficacy

Chlorambucil (Cbl) is a DNA alkylating drug in the nitrogen mustard family, but the clinical applications of nitrogen mustard antitumor drugs are frequently limited by their poor aqueous solubility, poor cellular uptake, lack of targeting, and severe side effects. Additionally, mitochondria are the energy factories for cells, and tumor cells are more susceptible to mitochondrial dysfunction than some healthy cells, thus making mitochondria an important target for tumor therapy. As a proof-of-concept, direct delivery of Cbl to tumor cells' mitochondria will probably bring about new opportunities for the nitrogen mustard family. Furthermore, IR775 chloride is a small-molecule lipophilic cationic heptamethine cyanine dye with potential advantages of mitochondria targeting, near-infrared (NIR) fluorescence imaging, and preferential internalization towards tumor cells. Here, an amphiphilic drug conjugate was facilely prepared by covalently coupling chlorambucil with IR775 chloride and further self-assembly to form a carrier-free self-delivery theranostic system, in which the two components are both functional units aimed at theranostic improvement. The theranostic IR775-Cbl potentiated typical "1 + 1 > 2" tumor inhibition through specific accumulation in mitochondria, which triggered a remarkable decrease in mitochondrial membrane potential and ATP generation. In vivo biodistribution and kinetic monitoring were achieved by real-time NIR fluorescence imaging to observe its transport inside a living body. Current facile mitochondria-targeting modification with clinically applied drugs was promising for endowing traditional drugs with targeting, imaging, and improved potency in disease theranostics.

An injectable hydrogel dressing for controlled release of hydrogen sulfide pleiotropically mediates the wound microenvironment

The healing of scalded wounds faces many challenges such as chronic inflammation, oxidative stress, wound infection, and difficulties in vascular and nerve regeneration. Treating a single problem cannot effectively coordinate the complex regenerative microenvironment of scalded wounds, limiting the healing and functional recovery of the skin. Therefore, there is a need to develop a multi-effect treatment plan that can adaptively address the issues at each stage of wound healing. In this study, we propose a scheme for on-demand release of hydrogen sulfide (H2S) based on the concentration of reactive oxygen species (ROS) in the wound microenvironment. This is achieved by encapsulating peroxythiocarbamate (PTCM) in the ROS-responsive polymer poly(ethylene glycol)-poly(L-methionine) (PMet) to form nanoparticles, which are loaded into a thermosensitive injectable hydrogel, F127-poly(L-aspartic acid-N-hydroxysuccinimide) (F127-P(Asp-NHS)), to create a scald dressing. The H2S released by the hydrogel dressing on demand regulates the wound microenvironment by alleviating infection, reducing oxidative stress, and remodeling inflammation, thereby accelerating the healing of full-thickness scalded wounds. This hydrogel dressing for the adaptive release of H2S has great potential in addressing complex scalded wounds associated with infection and chronic inflammation.

In Situ Rapid-Formation Sprayable Hydrogels for Challenging Tissue Injury Management

Rapid-acting, convenient, and broadly applicable medical materials are in high demand for the treatment of extensive and intricate tissue injuries in extremely medical scarcity environment, such as battlefields, wilderness, and traffic accidents. Conventional biomaterials fail to meet all the high criteria simultaneously for emergency management. Here, a multifunctional hydrogel system capable of rapid gelation and in situ spraying, addressing clinical challenges related to hemostasis, barrier establishment, support, and subsequent therapeutic treatment of irregular, complex, and urgent injured tissues, is designed. This hydrogel can be fast formed in less than 0.5 s under ultraviolet initiation. The precursor maintains an impressively low viscosity of 0.018 Pa s, while the hydrogel demonstrates a storage modulus of 0.65 MPa, achieving the delicate balance between sprayable fluidity and the mechanical strength requirements in practice, allowing flexible customization of the hydrogel system for differentiated handling and treatment of various tissues. Notably, the interactions between the component of this hydrogel and the cell surface protein confer upon its inherently bioactive functionalities such as osteogenesis, anti-inflammation, and angiogenesis. This research endeavors to provide new insights and designs into emergency management and complex tissue injuries treatment.

Natural polyphenolic antibacterial bio-adhesives for infected wound healing

Bio-adhesives used clinically, commonly have the ability to fill surgical voids and support wound healing, but which are devoid of antibacterial activity, and thus, could not meet the particular needs of the infected wound site. Herein, a series of natural polyphenolic antibacterial bio-adhesives were prepared via simple mixing and heating of polyphenols and acid anhydrides without any solvent or catalyst. Upon the acid anhydride ring opening and acylation reactions, various natural polyphenolic bio-adhesives could adhere to various substrates (i.e., tissue, wood, glass, rubber, paper, plastic, and metal) based on multi-interactions. Moreover, these bio-adhesives showed excellent antibacterial and anti-infection activity, rapid hemostatic performance and appropriate biodegradability, which could be widely used in promoting bacterial infection wound healing and hot burn infection wound repair. This work could provide a new strategy for strong adhesives using naturally occurring molecules, and provide a method for the preparation of novel multifunctional wound dressings for infected wound healing.

Swift Covalent Gelation Coupled with Robust Wet Adhesive Powder: A Novel Approach for Acute Massive Hemorrhage Control in Dynamic and High-Pressure Wound Environments

The quest for efficient hemostatic agents in emergency medicine is critical, particularly for managing massive hemorrhages in dynamic and high-pressure wound environments. Traditional self-gelling powders, while beneficial due to their ease of application and rapid action, fall short in such challenging conditions. To bridge this gap, the research introduces a novel self-gelling powder that combines ultrafast covalent gelation and robust wet adhesion, presenting a significant advancement in acute hemorrhage control. This ternary system comprises ε-polylysine (ε-PLL) and 4-arm polyethylene glycol succinyl succinate (4-arm-PEG-NHS) forming the hydrogel framework. Na2HPO4 functions as the "H+ sucker" to expedite the amidation reaction, slashing gelation time to under 10 s, crucial for immediate blood loss restriction. Moreover, PEG chains' hydrophilicity facilitates efficient absorption of interfacial blood, increasing the generated hydrogel's cross-linking density and strengthens its tissue bonding, thereby resulting in excellent mechanical and wet adhesion properties. In vitro experiments reveal the optimized formulation's exceptional tissue compliance, procoagulant activity, biocompatibility and antibacterial efficacy. In porcine models of heart injuries and arterial punctures, it outperforms commercial hemostatic agent Celox, confirming its rapid and effective hemostasis. Conclusively, this study presents a transformative approach to hemostasis, offering a reliable and potent solution for the emergency management of massive hemorrhage.

Naturally Derived Injectable Dual-Cross-Linked Adhesive Hydrogel for Acute Hemorrhage Control and Wound Healing

Developing biocompatible injectable hydrogels with high mechanical strength and rapid strong tissue adhesion for hemostatic sealing of uncontrolled bleeding remains a prevailing challenge. Herein, we engineer an injectable and photo-cross-linkable hydrogel based on naturally derived gelatin methacrylate (GelMA) and N-hydroxysuccinimide-modified poly(γ-glutamic acid) (γPGA-NHS). The chemically dual-cross-linked hydrogel rapidly forms after UV light irradiation and covalently bonds to the underlying tissue to provide robust adhesion. We demonstrate a significantly improved hemostatic efficacy of the hydrogel using various injury models in rats compared to the commercially available fibrin glue. Notably, the hydrogel can achieve hemostasis in porcine liver and spleen incision, and femoral artery puncture models. Moreover, the hydrogel is used for sutureless repair of the liver defect in a rat model with a significantly suppressed inflammatory response, enhanced angiogenesis, and superior healing efficacy compared to fibrin glue. Together, this study offers a promising bioadhesive for treating severe bleeding and facilitating wound repair.

Advancing homogeneous networking principles for the development of fatigue-resistant, low-swelling and sprayable hydrogels for sealing wet, dynamic and concealed wounds in vivo

Effective sealing of wet, dynamic and concealed wounds remains a formidable challenge in clinical practice. Sprayable hydrogel sealants are promising due to their ability to cover a wide area rapidly, but they face limitations in dynamic and moist environments. To address this issue, we have employed the principle of a homogeneous network to design a sprayable hydrogel sealant with enhanced fatigue resistance and reduced swelling. This network is formed by combining the spherical structure of lysozyme (LZM) with the orthotetrahedral structure of 4-arm-polyethylene glycol (4-arm-PEG). We have achieved exceptional sprayability by controlling the pH of the precursor solution. The homogeneous network, constructed through uniform cross-linking of amino groups in protein and 4-arm-PEG-NHS, provides the hydrogel with outstanding fatigue resistance, low swelling and sustained adhesion. In vitro testing demonstrated that it could endure 2000 cycles of underwater shearing, while in vivo experiments showed adhesion maintenance exceeding 24 h. Furthermore, the hydrogel excelled in sealing leaks and promoting ulcer healing in models including porcine cardiac hemorrhage, lung air leakage and rat oral ulcers, surpassing commonly used clinical materials. Therefore, our research presents an advanced biomaterial strategy with the potential to advance the clinical management of wet, dynamic and concealed wounds.

Progress in injectable hydrogels for the treatment of incompressible bleeding: an update

Uncontrollable haemorrhage from deep, noncompressible wounds remains a persistent and intractable challenge, accounting for a very high proportion of deaths in both war and disaster situations. Recently, injectable hydrogels have been increasingly studied as potential haemostatic materials, highlighting their enormous potential for the management of noncompressible haemorrhages. In this review, we summarize haemostatic mechanisms, commonly used clinical haemostatic methods, and the research progress on injectable haemostatic hydrogels. We emphasize the current status of injectable hydrogels as haemostatic materials, including their physical and chemical properties, design strategy, haemostatic mechanisms, and application in various types of wounds. We discuss the advantages and disadvantages of injectable hydrogels as haemostatic materials, as well as the opportunities and challenges involved. Finally, we propose cutting-edge research avenues to address these challenges and opportunities, including the combination of injectable hydrogels with advanced materials and innovative strategies to increase their biocompatibility and tune their degradation profile. Surface modifications for promoting cell adhesion and proliferation, as well as the delivery of growth factors or other biologics for optimal wound healing, are also suggested. We believe that this paper will inform researchers about the current status of the use of injectable haemostatic hydrogels for noncompressible haemorrhage and spark new ideas for those striving to propel this field forward.

Biomimetic, self-coacervating adhesive with tough underwater adhesion for ultrafast hemostasis and infected wound healing

Massive bleeding and wound infection due to severe traumas pose a huge threat to the life and health of sufferers; therefore, it is of clinical importance to fabricate adhesives with rapid hemostatic and superior antibacterial capabilities. However, the weak wet adhesion and insufficient function of existing bioadhesives limits their practical application. In this study, a sandcastle worm protein inspired polyelectrolyte self-coacervate adhesive of poly-γ-glutamic acid (PGA) and lysozyme (LZM) was developed. The adhesive exhibited strong underwater adhesion to various surfaces (>250 kPa for solid plates and >50 kPa for soft tissues) and maintained a 80 kPa even when soaked in water for 7 days. Rat liver and tail defect bleeding models revealed that the hemostatic efficiency was superior to that of commercial samples. The in vitro antimicrobial tests showed that the bacterial inhibition to Staphylococcus aureus and Escherichia coli reached almost 100%. Additionally, the infected wound regeneration model demonstrated that the healing rate of the adhesive group was about 100% within 15 days, which was greater than that of the control group. In vitro and in vivo experiments proved that this facilely prepared adhesive will be a promising material to fulfil the integration functions for rapid wound closure and facilitating wound healing.

In situ generated hemostatic adhesives: From mechanisms of action to recent advances and applications

Conventional surgical closure techniques, such as sutures, clips, or skin closure strips, may not always provide optimal wound closure and may require invasive procedures, which can result in potential post-surgical complications. As result, there is a growing demand for innovative solutions to achieve superior wound closure and improve patient outcomes. To overcome the abovementioned issues, in situ generated hemostatic adhesives/sealants have emerged as a promising alternative, offering a targeted, controllable, and minimally invasive procedure for a wide variety of medical applications. The aim of this review is to provide a comprehensive overview of the mechanisms of action and recent advances of in situ generated hemostatic adhesives, particularly protein-based, thermoresponsive, bioinspired, and photocrosslinkable formulations, as well as the design challenges that must be addressed. Overall, this review aims to enhance a comprehensive understanding of the latest advancements of in situ generated hemostatic adhesives and their mechanisms of action, with the objective of promoting further research in this field.

An injectable, self-healing, and antioxidant collagen- and hyaluronic acid-based hydrogel mediated with gallic acid and dopamine for wound repair

Injectable self-healing hydrogels with antioxidation are required in wound dressings. Because oxidative damage caused by excessive reactive oxygen species (ROS) is a common issue associated with chronic non-healing wounds. Here, collagen (COL) - and hyaluronic acid (HA)-based hydrogel with antioxidant and injectable self-healing mediated with gallic acid (GA) and dopamine (DA) offers unique advantages for wound repair. The hydrogel is constructed by COL-grafted GA (CG), HA-grafted DA (HD) and γ-poly(glutamic acid) (γ-PGA) coupled with 3-aminophenylboric acid (APBA) via the dynamic boronic ester bonds. Rheological measurements and direct visual observation demonstrated the hydrogel's desirable injectability and self-healing properties. Additionally, the hydrogel exhibits tissue adhesion properties. Biocompatibility and cell migration tests showed that the hydrogel promotes cell proliferation and migration. In vitro, antioxidant and intracellular free radical scavenging assays confirmed the hydrogel's antioxidant property and ability to scavenge excess ROS. In vivo wound healing studies have demonstrated that hydrogel can promote angiogenesis, inhibit inflammation, and promote collagen fiber deposition to accelerate wound healing.

Rapidly in situ forming an injectable Chitosan/PEG hydrogel for intervertebral disc repair

Intervertebral disc (IVD) degeneration occurred with the increasing age or accidents has puzzled peoples in daily life. To seal IVD defect by injectable hydrogels is a promising method for slowing down IVD degeneration. Herein, we reported a rapidly in situ forming injectable chitosan/PEG hydrogel (CSMA-PEGDA-L) through integrating photo-crosslink of methacrylate chitosan (CSMA) with Schiff base reaction between CSMA and aldehyde polyethylene glycol (PEGDA). The CSMA-PEGDA-L possessed a stronger compressive strength than the photo-crosslinked CSMA-L hydrogel and Schiff-base-crosslinked CSMA-PEGDA hydrogel. This chitosan/PEG hydrogel showed low cytotoxicity from incubation experiments of nucleus pulpous cells. When implanted on the punctured IVD of rat's tail, the CSMA-PEGDA-L hydrogel could well retard the progression of IVD degeneration through physical plugging, powerfully proven by radiological and histological evaluations. This work demonstrated the strategy of in situ injectable glue may be a potential solution for prevention of IVD degeneration.

Electron beam irradiation modified carboxymethyl chitin microsphere-based hemostatic materials with strong blood cell adsorption for hemorrhage control

Timely control of coagulopathy bleeding can effectively reduce the probability of wound infection and mortality. However, it is still a challenge for microsphere hemostatic agents to achieve timely control of coagulopathy bleeding. In this work, the CCM-g-AA@DA hemostatic agent based on carboxymethyl chitin microspheres, CCM, was synthesized using electron beam irradiation-induced grafting polymerization of acrylic acid and coupling with dopamine. Irradiation grafting endowed the microspheres with excellent adsorption performance and a rough surface. The microspheres showed a strong affinity to blood cells, especially red blood cells. The maximum adsorption of red blood cells is up to approximately 100 times that of the original microspheres, the CCM. The introduction of dopamine increased the tissue adhesion of the microspheres. At the same time, the microspheres still possessed good blood compatibility and biodegradability. Furthermore, the CCM-g-AA@DA with Fe3+ achieved powerful procoagulant effects in the rat anticoagulant bleeding model. The bleeding time and blood loss were both reduced by about 90% compared with the blank group, which was superior to that of the commercially available collagen hemostatic agent Avitene™. In summary, the CCM-g-AA@DA hemostatic agent shows promising potential for bleeding control in individuals with coagulation disorders.

A Choline Phosphoryl-Conjugated Chitosan/Oxidized Dextran Injectable Self-Healing Hydrogel for Improved Hemostatic Efficacy

The development of injectable hydrogels with good biocompatibility, self-healing, and superior hemostatic properties is highly desirable in emergency and clinical applications. Herein, we report an in situ injectable and self-healing hemostatic hydrogel based on choline phosphoryl functionalized chitosan (CS-g-CP) and oxidized dextran (ODex). The CP groups were hypothesized to accelerate hemostasis by facilitating erythrocyte adhesion and aggregation. Our results reveal that the CS-g-CP/ODex hydrogels exhibit enhanced blood clotting and erythrocyte adhesion/aggregation capacities compared to those of the CS/ODex hydrogels. The CS-g-CP₅₀/ODex₇₅ hydrogel presents rapid gelation time, good mechanical strength and tissue adhesiveness, satisfactory bursting pressure, and favorable biocompatibility. The hemostatic ability of the CS-g-CP₅₀/ODex₇₅ hydrogel was significantly improved compared to that of the CS/ODex hydrogel and commercial fibrin sealant in the rat tail amputation and liver/spleen injury models. Our study highlights the positive and synergistic effects of CP groups on hemostasis and strongly supports the CS-g-CP₅₀/ODex₇₅ hydrogel as a promising adhesive for hemorrhage control.

Silk Fibroin-Based Tough Hydrogels with Strong Underwater Adhesion for Fast Hemostasis and Wound Sealing

Rapid and strong adhesion of hydrogel adhesives is required for instant wound closure and hemostasis. However, in situ hydrogel formation and sufficient adhesion at target tissue sites in biological environments are severely compromised by the presence of blood and body fluids. In this work, an underwater adhesive hydrogel (named SHCa) is fabricated with rapid in situ gelation, enhanced mechanical toughness, and robust underwater adhesion. The SHCa can undergo rapid UV irradiation-induced gelation under water within 5 s and adhere firmly to underwater surfaces for 6 months. The synergistic effects of crystalline β-sheet structures and dynamic energy-dissipating mechanisms enhance the mechanical toughness and cohesion, supporting the balance between adhesion and cohesion in wet environments. Importantly, the SHCa can achieve rapid in situ gelation and robust underwater adhesion at various tissue surfaces in highly dynamic fluid environments, substantially outperforming the commercially available tissue adhesives. The lap shear adhesion strength and wound closure strength of SHCa on blood-covered substrates are 7.24 and 12.68 times higher than those of cyanoacrylate glue, respectively. Its fast hemostasis and wound sealing performance are further demonstrated in in vivo animal models. The proposed hydrogel with strong underwater adhesion provides an effective tool for fast wound closure and hemostasis.