Biomass-Derived Multilayer-Structured Microparticles for Accelerated Hemostasis and Bone Repair

One hydrophobic coating enables macro- and micro-scale blood contact activation

Efforts to develop hemostatic materials/devices have focused solely on enhanced liquid adsorption for concentrating blood components and/or new material forms for covering/sealing injured blood vessels. Considering the increasing coagulopathy conditions and versatile material forms, it is assumed to be valuable but inaccessible for creating universal hemostatic surfaces regardless of liquid-absorption property and coagulation component deficiency. Herein, we illustrate a facile polyphenol/alkyl (ATA) coating for macro-to-micro scale hemostatic materials that can integrate the virtues of contact-activation hemostatic property, low liquid-absorption property and applicability for healthy/coagulopathy conditions. Medical gauze with adequate ATA content, of highly hydrophobic surface that can reduce unnecessary blood absorption and bacterial adhesion at wounds, possesses the significantly higher hemostatic property than the pristine gauze. Macro-scale dressings/sheets and micro-scale particles are further modified with ATA for enhancing hemostatic properties, which verifies the valuable substrate compatibility and reveals the contact-activation hemostatic mechanism as the regulated blood (component)-material interactions. Not limited to the hemorrhage control in healthy rats/rabbits, these ATA-modified materials achieve potent hemostatic performance for intravascular hemostasis and coagulopathy condition. Our work thereby pioneers not only one potent hydrophobic coating for promising hemostatic materials, but also the appealing polyphenol/alkyl system for regulating protein/cell-material interactions.

Recent progress in polysaccharide microsphere-based hemostatic material for intravascular and extravascular hemostasis: A review

Hemorrhage, a common consequence of diseases, surgical procedures, and traffic accidents, poses a significant threat to public health. Effective hemostasis is crucial for patient survival and prognosis, particular in case of internal bleeding. While polysaccharide microsphere-based hemostatic materials have gained clinical acceptance due to their effectiveness, good biocompatibility, and versatility in both intravascular and extravascular hemostasis, they are limited by their single function and insufficient hemostatic properties. Recently, booming developments have been witnessed in microsphere-based biomaterials to achieve a combination therapy for hemostasis. This review first examines the fundamentals of coagulation process, hemostatic mechanisms, and microsphere fabrication techniques. We then discuss the latest investigations in functionalized microsphere-based hemostatic materials for controlling intravascular and extravascular hemorrhage, focusing on design strategies, hemostatic properties, and clinical implementation. Finally, we also propose some limitations and challenges of these hemostatic materials, aiming to provide valuable insights for future research in novel polysaccharide microsphere-based biomaterial.

Bactericidal Hemostatic Sponge: A Point of Care Solution to Combat Traumatic Injury

Uncontrollable haemorrhage and associated microbial contamination in the battlefield and civilian injuries pose a tremendous threat to healthcare professionals. Such traumatic wounds often necessitate an effective point-of-care solution to prevent the consequent morbidity owing to blood loss or haemorrhage. However, developing superior hemostatic materials with anti-infective properties remains a challenge. To address this, an injectable, cationic dextran-mesoporous silica nanoparticle-based bactericidal hemostatic sponge (BACSTAT) has been developed. A dual crosslinking approach is adopted through in situ covalent cross-linking through photo polymerization and silica nanoparticle-induced non-covalent interactions. This interconnected macroporous BACSTAT sponge has superior fluid absorption properties and fluid-induced rapid shape recovery of the sponge helps to seal the irregularly shaped wound. Furthermore, this sponge can stimulate a coagulation cascade for rapid blood clotting in mice femoral vein incision and liver puncture model. The optimum sponge exhibited potent antibacterial activity against wide-spectrum Gram-positive and Gram-negative pathogens. Notably, it is completely biocompatible with mammalian cells and mice skin. Significantly, this sponge reduces Pseudomonas aeruginosa burden >99% in mice subcutaneous infection model with substantially lessening inflammatory responses in infected tissues. Collectively, the optimized sponge bears immense potential to be developed as point-of-care solution for military and civilian traumatic injury.

Smart design in biopolymer-based hemostatic sponges: From hemostasis to multiple functions

Uncontrolled hemorrhage remains the leading cause of death in clinical and emergency care, posing a major threat to human life. To achieve effective bleeding control, many hemostatic materials have emerged. Among them, nature-derived biopolymers occupy an important position due to the excellent inherent biocompatibility, biodegradability and bioactivity. Additionally, sponges have been widely used in clinical and daily life because of their rapid blood absorption. Therefore, we provide the overview focusing on the latest advances and smart designs of biopolymer-based hemostatic sponge. Starting from the component, the applications of polysaccharide and polypeptide in hemostasis are systematically introduced, and the unique bioactivities such as antibacterial, antioxidant and immunomodulation are also concerned. From the perspective of sponge structure, different preparation processes can obtain unique physical properties and structures, which will affect the material properties such as hemostasis, antibacterial and tissue repair. Notably, as development frontier, the multi-functions of hemostatic materials is summarized, mainly including enhanced coagulation, antibacterial, avoiding tumor recurrence, promoting tissue repair, and hemorrhage monitoring. Finally, the challenges facing the development of biopolymer-based hemostatic sponges are emphasized, and future directions for in vivo biosafety, emerging materials, multiple application scenarios and translational research are proposed.

A tannic acid coated silk fibroin sponge loaded with bioglass for noncompressible hemostasis

A hemostatic sponge designed for hemostasis of noncompressible penetrating wounds should exhibit rapid shape recovery, strong coagulation activity, and effective antibacterial property. In this study, we prepared a tannic acid coated silk fibroin sponge loaded with bioglass.In vitro, the sponge had a three-dimensional porous structure, good liquid adsorption capacity, and a water-triggered shape recovery feature. The sponge possessed strong coagulation activity and antibacterial property, while exhibiting low cytotoxicity and minimal hemolytic effects.In vivo, the sponge showed a greater advantage in controlling bleeding from both rat liver injury and penetrating wounds compared to commercial gauze and gelatin sponge. In conclusion, the developed sponge can be promising for noncompressible hemostasis.

Implantable Dental Barrier Membranes as Regenerative Medicine in Dentistry: A Comprehensive Review

BACKGROUND

Periodontitis and bone loss in the maxillofacial and dental areas pose considerable challenges for both functional and aesthetic outcomes. To date, implantable dental barrier membranes, designed to prevent epithelial migration into defects and create a favorable environment for targeted cells, have garnered significant interest from researchers. Consequently, a variety of materials and fabrication methods have been explored in extensive research on regenerative dental barrier membranes.

METHODS

This review focuses on dental barrier membranes, summarizing the various biomaterials used in membrane manufacturing, fabrication methods, and state-of-the-art applications for dental tissue regeneration. Based on a discussion of the pros and cons of current membrane strategies, future research directions for improved membrane designs are proposed.

RESULTS AND CONCLUSION

To endow dental membranes with various biological properties that accommodate different clinical situations, numerous biomaterials and manufacturing methods have been proposed. These approaches provide theoretical support and hold promise for advancements in dental tissue regeneration.

Serotonin-functionalized starch-based hemostatic sponges enhance platelet activation in the management of non-compressible hemorrhage

Massive hemorrhage poses a serious threat to human health and even life. Access to rapid and potent hemostatic materials is crucial for lowering mortality rates. Starch-based materials exhibit good biocompatibility and are extensively utilized in hemostatic. However, existing starch-based hemostatic products suffer from limited hemostatic efficacy. Serotonin, an indoleamine naturally occurring in the human body, is recognized for its potent platelet-activating properties. Therefore, this study focused on enhancing the procoagulant activity of starch by incorporating serotonin into the starch backbone via esterification and amidation reactions, yielding a novel serotonin-loaded starch-based hemostatic sponge (SLS sponge). The SLS sponges featured exceptional porosity (≥80 %) and water absorption capacity (≥2000 %), which rapidly initiated the coagulation cascade reaction, promoted the adhesion and aggregation of red blood cells and platelets, and intensified platelet activation. This multifaceted approach synergistically enhanced hemostasis via both active and passive coagulation mechanisms. Notably, the SLS sponges adhered firmly to the wound surfaces without pressure. Compared with gelatin sponges, the SLS sponges significantly reduced blood loss by approximately 40.5 % and shortened the time to achieve hemostasis by approximately 28.9 %. These findings indicate that the newly developed SLS sponges are a promising active hemostatic material, particularly effective in managing non-compressible hemorrhages.

Biomimetic Scaffolds Regulating the Iron Homeostasis for Remolding Infected Osteogenic Microenvironment

The treatment of infected bone defects (IBDs) needs simultaneous elimination of infection and acceleration of bone regeneration. One mechanism that hinders the regeneration of IBDs is the iron competition between pathogens and host cells, leading to an iron deficient microenvironment that impairs the innate immune responses. In this work, an in situ modification strategy is proposed for printing iron-active multifunctional scaffolds with iron homeostasis regulation ability for treating IBDs. As a proof-of-concept, ultralong hydroxyapatite (HA) nanowires are modified through in situ growth of a layer of iron gallate (FeGA) followed by incorporation in the poly(lactic-co-glycolic acid) (PLGA) matrix to print biomimetic PLGA based composite scaffolds containing FeGA modified HA nanowires (FeGA-HA@PLGA). The photothermal effect of FeGA endows the scaffolds with excellent antibacterial activity. The released iron ions from the FeGA-HA@PLGA help restore the iron homeostasis microenvironment, thereby promoting anti-inflammatory, angiogenesis and osteogenic differentiation. The transcriptomic analysis shows that FeGA-HA@PLGA scaffolds exert anti-inflammatory and pro-osteogenic differentiation by activating NF-κB, MAPK and PI3K-AKT signaling pathways. Animal experiments confirm the excellent bone repair performance of FeGA-HA@PLGA scaffolds for IBDs, suggesting the promising prospect of iron homeostasis regulation therapy in future clinical applications.

Hyaluronic Acid-Based Microparticles with Lubrication and Anti-Inflammation for Alleviating Temporomandibular Joint Osteoarthritis

The pathogenesis of temporomandibular joint osteoarthritis (TMJOA) is closely associated with mechanical friction, which leads to the up-regulation of inflammatory mediators and the degradation of articular cartilage. Injectable drug-loaded microparticles have attracted widespread interest in intra-articular treatment of TMJOA by providing lubrication and facilitating localized drug delivery. Herein, a hyaluronic acid-based microparticle is developed with excellent lubrication properties, drug loading capacity, antioxidant activity, and anti-inflammatory effect for the treatment of TMJOA. The microparticles are facilely prepared by the self-assembly of 3-aminophenylboronic acid-modified hyaluronic acid (HP) through hydrophobic interaction in an aqueous solution, which can further encapsulate diol-containing drugs through dynamic boronate ester bonds. The resulting microparticles demonstrate excellent injectability, lubrication properties, radical scavenging efficiency, and antibacterial activity. Additionally, the drug-loaded microparticles exhibit a favorable cytoprotective effect on chondrocyte cells in vitro under an oxidative stress microenvironment. In vivo experiments validate that intra-articular injection of drug-loaded microparticles effectively alleviates osteoporosis-like damage, suppresses inflammatory response, and facilitates matrix regeneration in the treatment of TMJOA. The HP microparticles demonstrate excellent injectability and encapsulation capacity for diol-containing drugs, highlighting its potential as a versatile drug delivery vehicle in the intra-articular treatment of TMJOA.

A macromolecular cross-linked alginate aerogel with excellent concentrating effect for rapid hemostasis

Alginate-based materials present promising potential for emergency hemostasis due to their excellent properties, such as procoagulant capability, biocompatibility, low immunogenicity, and cost-effectiveness. However, the inherent deficiencies in water solubility and mechanical strength pose a threat to hemostatic efficiency. Here, we innovatively developed a macromolecular cross-linked alginate aerogel based on norbornene- and thiol-functionalized alginates through a combined thiol-ene cross-linking/freeze-drying process. The resulting aerogel features an interconnected macroporous structure with remarkable water-uptake capacity (approximately 9000 % in weight ratio), contributing to efficient blood absorption, while the enhanced mechanical strength of the aerogel ensures stability and durability during the hemostatic process. Comprehensive hemostasis-relevant assays demonstrated that the aerogel possessed outstanding coagulation capability, which is attributed to the synergistic impacts on concentrating effect, platelet enrichment, and intrinsic coagulation pathway. Upon application to in vivo uncontrolled hemorrhage models of tail amputation and hepatic injury, the aerogel demonstrated significantly superior performance compared to commercial alginate hemostatic agent, yielding reductions in clotting time and blood loss of up to 80 % and 85 %, respectively. Collectively, our work illustrated that the alginate porous aerogel overcomes the deficiencies of alginate materials while exhibiting exceptional performance in hemorrhage, rendering it an appealing candidate for rapid hemostasis.

Targeted Protein Fate Modulating Functional Microunits Promotes Intervertebral Fusion

Stable regulation of protein fate is a prerequisite for successful bone tissue repair. As a ubiquitin-specific protease (USP), USP26 can stabilize the protein fate of β-catenin to promote the osteogenic activity of mesenchymal cells (BMSCs) and significantly increased bone regeneration in bone defects in aged mice. However, direct transfection of Usp26 in vivo is inefficient. Therefore, improving the efficient expression of USP26 in target cells is the key to promoting bone tissue repair. Herein, 3D printing combined with microfluidic technology is applied to construct a functional microunit (protein fate regulating functional microunit, denoted as PFFM), which includes GelMA microspheres loaded with BMSCs overexpressing Usp26 and seeded into PCL 3D printing scaffolds. The PFFM provides a microenvironment for BMSCs, significantly promotes adhesion, and ensures cell activity and Usp26 supplementation that stabilizes β-catenin protein significantly facilitates BMSCs to express osteogenic phenotypes. In vivo experiments have shown that PFFM effectively accelerates intervertebral bone fusion. Therefore, PFFM can provide new ideas and alternatives for using USP26 for intervertebral fusion and other hard-to-repair bone defect diseases and is expected to provide clinical translational potential in future treatments.

A facile Immunoregulatory Constructional Design by Proanthocyanidin Optimizing Directional Chitosan Microchannel

Improving the interconnected structure and bioregulatory function of natural chitosan is beneficial for optimizing its performance in bone regeneration. Here, a facile immunoregulatory constructional design is proposed for developing instructive chitosan by directional freezing and alkaline salting out. The molecular dynamics simulation confirmed the assembly kinetics and structural features of various polyphenols and chitosan molecules. Along with the in vitro anti-inflammatory, antioxidative, promoting bone mesenchymal stem cell (BMSC) adhesion and proliferation performance, proanthocyanidin optimizing chitosan (ChiO) scaffold presented an optimal immunoregulatory structure with the directional microchannel. Transcriptome analysis in vitro further revealed the cytoskeleton- and immune-regulation effect of ChiO are the key mechanism of action on BMSC. The rabbit cranial defect model (Φ = 10 mm) after 12 weeks of implantation confirmed the significantly enhanced bone reconstitution. This facile immunoregulatory directional microchannel design provides effective guidance for developing inducible chitosan scaffolds.

Silk fibroin-based hemostatic powders with instant and robust adhesion performance for sutureless sealing of gastrointestinal defects

Powder-based hemostatic technology has offered unprecedented opportunities in surgical sealing and repair of irregularly shaped and noncompressible wounds. Despite their routine use, existing clinical hemostatic powders are challenged either by poor mechanical properties or inadequate adhesion to bleeding tissues in biological environments. Here, inspired by the mussel foot proteins' fusion assembly strategy, a novel silk fibroin-based hemostatic powder (named as SF/PEG/TA) with instant and robust adhesion performance is developed. Upon absorbing interfacial liquids, the SF/PEG/TA powders rapidly swell into micro-gels and subsequently contact with each other to transform into a macroscopically homogeneous hydrogel in situ, strengthening its interfacial bonding with various substrates in fluidic environments. The in vitro and in vivo results show that the SF/PEG/TA powder possesses ease of use, good biocompatibility, strong antibacterial activities, and effective blood clotting abilities. The superior hemostatic sealing capability of the SF/PEG/TA powder is demonstrated in the rat liver, heart, and gastrointestinal injury models. Moreover, in vivo investigation of rat skin incision and gastrointestinal perforation models validates that the SF/PEG/TA powder promotes wound healing and tissue regeneration. Taken together, compared to existing clinical hemostatic powders, the proposed SF/PEG/TA powder with superior wound treatment capabilities has high potential for clinical hemostasis and emergency rescue.

Proanthocyanidins-based tandem dynamic covalent cross-linking hydrogel for diabetic wound healing

Wound healing in diabetic patients presents significant challenges in clinical wound care due to high oxidative stress, excessive inflammation, and a microenvironment prone to infection. In this study, we successfully developed a multifunctional tandem dynamic covalently cross-linked hydrogel dressing aimed at diabetic wound healing. This hydrogel was constructed using cyanoacetic acid functionalized dextran (Dex-CA), 2-formylbenzoylboric acid (2-FPBA) and natural oligomeric proanthocyanidins (OPC), catalyzed by histidine. The resulting Dex-CA/OPC/2-FPBA (DPOPC) hydrogel can be dissolved triggered by cysteine, thereby achieving "controllable and non-irritating" dressing change. Furthermore, the incorporation of OPC as a hydrogel building block endowed the hydrogel with antioxidant and anti-inflammatory properties. The cross-linked network of the DPOPC hydrogel circumvents the burst release of OPC, enhancing its biosafety. In vivo studies demonstrated that the DPOPC hydrogel significantly accelerated the wound healing process in diabetic mice compared to a commercial hydrogel, achieving an impressive wound closure rate of 98 % by day 14. The DPOPC hydrogel effectively balanced the disrupted inflammatory state during the healing process. This dynamic hydrogel based on natural polyphenols is expected to be an ideal candidate for dressings intended for chronic wounds.

Lithium-Doped Titanium Dioxide-Based Multilayer Hierarchical Structure for Accelerating Nerve-Induced Bone Regeneration

Despite considerable advances in artificial bone tissues, the absence of neural network reconstruction in their design often leads to delayed or ineffective bone healing. Hence, we propose a multilayer hierarchical lithium (Li)-doped titanium dioxide structure, constructed through microarc oxidation combined with alkaline heat treatment. This structure can induce the sustained release of Li ions, mimicking the environment of neurogenic osteogenesis characterized by high brain-derived neurotrophic factor (BDNF) expression. During in vitro experiments, the structure enhanced the differentiation of Schwann cells (SCs) and the growth of human umbilical vein endothelial cells (HUVECs) and mouse embryo osteoblast progenitor cells (MC3T3-E1). Additionally, in a coculture system, the SC-conditioned media markedly increased alkaline phosphatase expression and the formation of calcium nodules, demonstrating the excellent potential of the material for nerve-induced bone regeneration. In an in vivo experiment based on a rat distal femoral lesion model, the structure substantially enhanced bone healing by increasing the density of the neural network in the tissue around the implant. In conclusion, this study elucidates the neuromodulatory pathways involved in bone regeneration, providing a promising method for addressing bone deformities.

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.

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

A Janus Gelatin Sponge with a Procoagulant Nanoparticle-Embedded Surface for Coagulopathic Hemostasis

Apart from the wide and safe application of natural polymer-based hemostatic materials/devices, it is still desirable to develop new types of hemostatic materials that can achieve both potent coagulopathic hemostasis and a facile preparation process. In this work, one Janus gelatin sponge (J-ZGS) is readily constructed for both coagulation-dependent and coagulopathic hemostasis by embedding zein nanoparticles on the surface of a self-prepared gelatin sponge (S-GS): zein nanoparticles were facilely prepared by an antisolvent method to achieve procoagulant blood-material interactions, while S-GS was prepared by freeze-drying a foaming gelatin solution. Due to the distinct secondary structure, the optimal zein nanoparticles possessed a higher in vitro hemostatic property than the pristine zein powder and other nanoparticles, the underlying mechanism of which was revealed as the superior RBC/platelet adhesion property in the presence/absence of plasma proteins. Compared with S-GS and a commercial gelatin sponge, J-ZGS achieved a significantly higher in vitro hemostatic property and similarly good blood compatibility/cytocompatibility. Moreover, in vivo artery-injury models confirmed the outstanding hemostatic performance of J-ZGS under both coagulation-dependent and coagulopathic conditions. Our work offers an appealing approach for developing potent hemostatic sponges from natural polymer-based nanoparticles that could be further extended to versatile hemostatic materials for coagulopathic hemostasis.

Tuning Blood-Material Interactions to Generate Versatile Hemostatic Powders and Gels

Polymer-based hemostatic materials/devices have been increasingly exploited for versatile clinical scenarios, while there is an urgent need to reveal the rational design/facile approach for procoagulant surfaces through regulating blood-material interactions. In this work, degradable powders (PLPS) and thermoresponsive gels (F127-PLPS) are readily developed as promising hemostatic materials for versatile clinical applications, through tuning blood-material interactions with optimized grafting of cationic polylysine: the former is facilely prepared by conjugating polylysine onto porous starch particle, while F127-PLPS is prepared by the simple mixture of PLPS and commercial thermosensitive polymer. In vitro and in vivo results demonstrate that PLPS2 with the optimal-/medium content of polylysine grafts achieve the superior hemostatic performance. The underlying procoagulant mechanism of PLPS2 surface is revealed as the selective fibrinogen adsorption among the competitive plasma-protein-adsorption process, which is the foundation of other blood-material interactions. Moreover, in vitro results confirm the achieved procoagulant surface of F127-PLPS through optimal PLPS2 loading. Together with the tunable thermoresponsiveness, F127-PLPS exhibits outstanding hemostatic utilization in both femoral-artery-injury and renal-artery-embolization models. The work thereby pioneers an appealing approach for generating versatile polymer-based hemostatic materials/devices.

Benzeneboronic-alginate/quaternized chitosan-catechol powder with rapid self-gelation, wet adhesion, biodegradation and antibacterial activity for non-compressible hemorrhage control

Although hemostatic powders have excellent adaptability for irregular and inaccessible wounds, their hemostasis for continuous bleeding or bleeding wounds of non-compressible organs remains a critical challenge. Herein, a series of benzeneboronic acid-modified sodium alginate/catechol-modified quaternized chitosan (SA-BA/QCS-C, SBQCC) powders is developed by borate ester crosslinking for non-compressible hemorrhage control. SBQCC powders possess remarkable tissue adhesion, rapid self-gelation, good cytocompatibility and antibacterial activity against S. aureus and E. coil. The blood coagulation assays show that SBQCC powders display excellent blood clotting ability due to the synergistic effect of SA-BA and QCS-C. The SBQCC2 powder with the SA-BA to QCS-C mass ratio of 5 to 3 has the greatest effect on the blood-clotting rate. Upon depositing SBQCC2 powder to bleeding wounds of rabbit liver, the powder can absorb a large amount of blood and form a stable hydrogel physical barrier at the bleeding wounds in situ to achieve non-pressing rapid hemostasis. The SBQCC2 powder also has good biocompatibility and can be degraded in vivo. Altogether, the SBQCC powders can be a promising candidate for rapid hemostasis, and these findings may provide a new perspective for improving the hemostatic efficiency of the hemostatic powder in biomedical fields.

Rational Design of Bioactive Materials for Bone Hemostasis and Defect Repair

Everyday unnatural events such as trauma, accidents, military conflict, disasters, and even medical malpractice create open wounds and massive blood loss, which can be life-threatening. Fractures and large bone defects are among the most common types of injuries. Traditional treatment methods usually involve rapid hemostasis and wound closure, which are convenient and fast but may result in various complications such as nerve injury, deep infection, vascular injury, and deep hematomas. To address these complications, various studies have been conducted on new materials that can be degraded in the body and reduce inflammation and abscesses in the surgical area. This review presents the latest research progress in biomaterials for bone hemostasis and repair. The mechanisms of bone hemostasis and bone healing are first introduced and then principles for rational design of biomaterials are summarized. After providing representative examples of hemostatic biomaterials for bone repair, future challenges and opportunities in the field are proposed.

Multifunctional calcium polyphenol networks reverse the hostile microenvironment of trauma for preventing postoperative peritoneal adhesions

Abdominal adhesions, a commonly observed complication of abdominal surgery, have a high incidence and adversely affect patients' physical and mental health. The primary causes of abdominal adhesions are intraoperative trauma, acute inflammatory response, bleeding, and foreign body infection. Because most current treatment approaches for abdominal adhesions are limited, improved and novel postoperative anti-adhesion regimens are urgently needed. In this study, we developed calcium polyphenol network (CaPN) microspheres based on the self-assembly of the natural triphenolic compound gallic acid and Ca2+ in solution. The physicochemical properties of CaPNs, including their hemostatic, antibacterial, antioxidant, and anti-inflammatory activities, were investigated in vitro. Bleeding and cecal-abdominal wall adhesion models were established to observe the hemostatic activity of CaPNs and their preventive effect on postoperative abdominal wall adhesion in vivo. The results showed that CaPNs significantly reduced inflammation, oxidative stress, fibrosis, and abdominal adhesion formation and had good hemostatic and antibacterial properties. Our findings suggest a novel strategy for the prevention of postoperative adhesions.

Water-Triggered Segment Orientation of Long-Lasting Anti-Biofouling Polyurethane Coatings on Biomedical Catheters via Solvent Exchange Strategy

The formation of biofilm and thrombus on medical catheters poses a significant life-threatening concern. Hydrophilic anti-biofouling coatings upon catheter surfaces with complex shapes and narrow lumens are demonstrated to have the potential in reducing complications. However, their effectiveness is constrained by poor mechanical stability and weak substrate adhesion. Herein, a novel zwitterionic polyurethane (SUPU) with strong mechanical stability and long-term anti-biofouling is developed by controlling the ratio of sulfobetaine-diol and ureido-pyrimidinone. Once immersed in water, as-synthesized zwitterionic coating (SUPU3 SE) would undergo a water-driven segment reorientation to obtain much higher durability than its direct drying one, even under various extreme treatments, including acidic solution, abrasion, ultrasonication, flushing, and shearing, in PBS at 37 °C for 14 days. Moreover, SUPU3 SE coating could achieve a 97.1% of exceptional reducing protein fouling, complete prevention of cell adhesion, and long-lasting anti-biofilm performance even after 30 days. Finally, the good anti-thrombogenic formations of SUPU3 SE coating with bacterial treatment are validated in blood circulation through an ex vivo rabbit arteriovenous shunt model. This work provides a facile approach to fabricating stable hydrophilic coating through a simple solvent exchange to reduce thrombosis and infection of biomedical catheters.

Sea Cucumber-Inspired Aerogel for Ultrafast Hemostasis of Open Fracture

The symptomatic management of hemorrhagic shock complicated by open fractures is a great challenge, because it is also complicated by complex wound bleeding, bacterial infection, and bone defects. Inspired by the water absorption and cross-sectional microstructure of sea cucumbers, in this study, a new sea cucumber-like aerogel (GCG) is proposed. Its aligned porous structure and composition can stop bleeding rapidly and effectively with a blood clotting index of 3.73 ± 1.8%. More importantly, the data of in vivo hemostasis test in an amputating rat tail hemostatic model (15.69 ± 2.45 s, 26.95 ± 8.43 mg) and liver puncture bleeding model (23.77 ± 2.68 s, 36.22 ± 16.92 mg) also indicate the excellent hemostatic performance of GCG. In addition, GCG also shows a significant inhibitory effect on S. aureus and E. coli, which can prevent the occurrence of postoperative osteomyelitis. Not only that, after filling in the bone defect, it is shown that this GCG aerogel completely degrades eight weeks after surgery and induces new bone ingrowth, achieving functional regeneration after hemostasis of an open fracture defect. Generally, because of its combination of hemostatic, antibacterial, and osteogenic activities, this new aerogel is a promising option for open fractures treatment.

Strong tissue adhesive polyelectrolyte complex powders based on low molecular weight chitosan for acute hemorrhage control

Self-gelling and bioadhesive powders offered promising effective hemostats to suit irregularly shaped, complex and non-compressible wounds for clinical applications. In the current study, chitosan based polyelectrolyte complex coacervate were simply prepared by mixing high concentrations (10 %) of low molecular weight chitosan (CS) and polyacrylic acid (PAA) solutions. Obtained by lyophilization, the physical cross-linked polyelectrolyte complex powders would form a gel within 5 s upon hydration, which demonstrated excellent mechanical properties, significant antibacterial activities, strong and lasting adhesion on wet tissues in physiological environment. In vitro blood clotting assays showed that the CS/PAA powders could remarkably aggregate blood cells and accelerate blood clotting process. As studied by diverse hemorrhage models, including rat tail, liver and heart injuries and dog incision, CS/PAA powders significantly facilitated the decrease of blood loss as well as hemostatic time by creating robust physical barriers and promoting blood clot formation on the bleeding sites. These outstanding properties in terms of easy preparation, rapid self-gelling, strong wet adhesion, effective hemostasis and shape-adaptability endowed CS/PAA polyelectrolyte complex powders with great potential in managing acute hemorrhage of non-compressible trauma.

Cell unit-inspired natural nano-based biomaterials as versatile building blocks for bone/cartilage regeneration

The regeneration of weight-bearing bone defects and critical-sized cartilage defects remains a significant challenge. A wide range of nano-biomaterials are available for the treatment of bone/cartilage defects. However, their poor compatibility and biodegradability pose challenges to the practical applications of these nano-based biomaterials. Natural biomaterials inspired by the cell units (e.g., nucleic acids and proteins), have gained increasing attention in recent decades due to their versatile functionality, compatibility, biodegradability, and great potential for modification, combination, and hybridization. In the field of bone/cartilage regeneration, natural nano-based biomaterials have presented an unparalleled role in providing optimal cues and microenvironments for cell growth and differentiation. In this review, we systematically summarize the versatile building blocks inspired by the cell unit used as natural nano-based biomaterials in bone/cartilage regeneration, including nucleic acids, proteins, carbohydrates, lipids, and membranes. In addition, the opportunities and challenges of natural nano-based biomaterials for the future use of bone/cartilage regeneration are discussed.

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.

Hemostasis-osteogenesis integrated Janus carboxymethyl chitin/hydroxyapatite porous membrane for bone defect repair

Barrier membranes with osteogenesis are desirable for promoting bone repair. Janus membrane, which has a bilayered structure with different properties on each side, could meet the osteogenesis/barrier dual functions of guided bone regeneration. In this work, new biodegradable Janus carboxymethyl chitin membrane with asymmetric pore structure was prepared based on thermosensitive carboxymethyl chitin without using any crosslinkers. Nano-hydroxyapatites were cast on single-sided membrane. The obtained carboxymethyl chitin/nano-hydroxyapatite Janus membrane showed dual biofunctions: the dense layer of the Janus membrane could act as a barrier to prevent connective tissue cells from invading the bone defects, while the porous layer (with pore size 100-200 μm) containing nano-hydroxyapatite could guide bone regeneration. After implanted on the rat critical-sized calvarial defect 8 weeks, carboxymethyl chitin/nano-hydroxyapatite membrane showed the most newly formed bone tissue with the highest bone volume/total volume ratio (10.03 ± 1.81 %, analyzed by micro CT), which was significantly better than the commercial collagen membrane GTR® (5.05 ± 0.76 %). Meanwhile, this Janus membrane possessed good hemostatic ability. These results suggest a facile strategy to construct hemostasis-osteogenesis integrated Janus carboxymethyl chitin/hydroxyapatite membrane for guided bone regeneration.

Multi-layer-structured bioactive glass nanopowder for multistage-stimulated hemostasis and wound repair

Current treatments for full-thickness skin injuries are still unsatisfactory due to the lack of hierarchically stimulated dressings that can integrate the rapid hemostasis, inflammation regulation, and skin tissue remodeling into the one system instead of single-stage boosting. In this work, a multilayer-structured bioactive glass nanopowder (BGN@PTE) is developed by coating the poly-tannic acid and ε-polylysine onto the BGN via facile layer-by-layer assembly as an integrative and multilevel dressing for the sequential management of wounds. In comparison to BGN and poly-tannic acid coated BGN, BGN@PTE exhibited the better hemostatic performance because of its multiple dependent approaches to induce the platelet adhesion/activation, red blood cells (RBCs) aggregation and fibrin network formation. Simultaneously, the bioactive ions from BGN facilitate the regulation of the inflammatory response while the poly-tannic acid and antibacterial ε-polylysine prevent the wound infection, promoting the wound healing during the inflammatory stage. In addition, BGN@PTE can serve as a reactive oxygen species scavenger, alleviate the oxidation stress in wound injury, induce the cell migration and angiogenesis, and promote the proliferation stage of wound repair. Therefore, BGN@PTE demonstrated the significantly higher wound repair capacity than the commercial bioglass dressing Dermlin™. This multifunctional BGN@PTE is a potentially valuable dressing for full-thickness wound management and may be expected to extend to the other wounds therapy.

Mitochondrial-Targeted Delivery of Polyphenol-Mediated Antioxidases Complexes against Pyroptosis and Inflammatory Diseases

Excess accumulation of mitochondrial reactive oxygen species (mtROS) is a key target for inhibiting pyroptosis-induced inflammation and tissue damage. However, targeted delivery of drugs to mitochondria and efficient clearance of mtROS remain challenging. In current study, it is discovered that polyphenols such as tannic acid (TA) can mediate the targeting of polyphenol/antioxidases complexes to mitochondria. This affinity does not depend on mitochondrial membrane potential but stems from the strong binding of TA to mitochondrial outer membrane proteins. Taking advantage of the feasibility of self-assembly between TA and proteins, superoxide dismutase, catalase, and TA are assembled into complexes (referred to as TSC) for efficient enzymatic activity maintenance. In vitro fluorescence confocal imaging shows that TSC not only promoted the uptake of biological enzymes in hepatocytes but also highly overlapped with mitochondria after lysosomal escape. The results from an in vitro model of hepatocyte oxidative stress demonstrate that TSC efficiently scavenges excess mtROS and reverses mitochondrial depolarization, thereby inhibiting inflammasome-mediated pyroptosis. More interestingly, TSC maintain superior efficacy compared with the clinical gold standard drug N-acetylcysteine in both acetaminophen- and D-galactosamine/lipopolysaccharide-induced pyroptosis-related hepatitis mouse models. In conclusion, this study opens a new paradigm for targeting mitochondrial oxidative stress to inhibit pyroptosis and treat inflammatory diseases.

A natural polyphenol-functionalized chitosan/gelatin sponge for accelerating hemostasis and infected wound healing

Natural polymers have been particularly appealing for constructing hemostatic materials/devices, but it is still desirable to develop new natural polymer-based biomaterials with balanced hemostatic and wound-healing performance. In this work, a natural polyphenol-functionalized chitosan/gelatin sponge (PCGS) was prepared by the lyophilization of a chitosan/gelatin mixture solution (under a self-foaming condition to prepare the CGS) and subsequent chemical cross-linking with procyanidin (PC). Compared with the original CGS, PCGS exhibited an enhanced liquid-absorption ability, reduced surface charges, and similar/low hemolysis rate. Benefiting from such a liquid-absorption ability (∼4000% for whole blood and normal saline) and moderate surface charges, PCGS exhibited high in vitro hemostatic property and promising hemostatic performance in an in vivo femoral-artery-injury model. In addition, PCGS possessed higher antioxidant property and slightly decreased antibacterial ability than CGS, owing to the incorporation of PC. The feasibility of PCGS for treating infected wounds was further confirmed in an in vivo infected-tooth-extraction model, as the typical complication of intractable tooth-extraction bleeding. The present work demonstrated a facile approach for developing multifunctional hemostatic materials through the flexible management of natural polymers and polyphenols.

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.

Starch-based shape memory sponge for rapid hemostasis in penetrating wounds

Death caused by excessive blood loss has always been a global concern. Timely control of bleeding in incompressible penetrated wounds remains a great challenge. Here, we developed a shape memory sponge (SQG) based on modified starch and gelatin (Gel) to control the hemorrhage of penetrating wounds. The porous structure of SQG greatly enhanced the absorption of blood, and the adhesion of erythrocytes and platelets. The water absorption rate of SQG reached 1178.72 ± 12.18% in 10 s. SQG quickly recovered its shape in water (∼3 s) and exhibited high mechanical strength (∼38 kPa), acting as a physically packed barrier to facilitate hemostasis. Furthermore, the positively charged sponges were conducive to activating platelets and promoting the release of coagulation factors. SQG sponges possessed the lowest blood coagulation index (BCI) of 21.32 ± 0.19%, and presented good biocompatibility and obvious inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Moreover, SQG sponges controlled complete bleeding in 69 ± 20 s and a bleeding loss of 334 ± 138 mg was observed, nearly 50% lower than that of gelatin sponge in rabbit liver penetrating wounds. Overall, SQG possesses a combination of potent shape recovery, rapid hemostasis, and excellent antibacterial and degradation ability, enabling promising applications for hemostasis in non-compressible penetrating wounds.

The Role of Microsphere Structures in Bottom-Up Bone Tissue Engineering

Bone defects have caused immense healthcare concerns and economic burdens throughout the world. Traditional autologous allogeneic bone grafts have many drawbacks, so the emergence of bone tissue engineering brings new hope. Bone tissue engineering is an interdisciplinary biomedical engineering method that involves scaffold materials, seed cells, and "growth factors". However, the traditional construction approach is not flexible and is unable to adapt to the specific shape of the defect, causing the cells inside the bone to be unable to receive adequate nourishment. Therefore, a simple but effective solution using the "bottom-up" method is proposed. Microspheres are structures with diameters ranging from 1 to 1000 µm that can be used as supports for cell growth, either in the form of a scaffold or in the form of a drug delivery system. Herein, we address a variety of strategies for the production of microspheres, the classification of raw materials, and drug loading, as well as analyze new strategies for the use of microspheres in bone tissue engineering. We also consider new perspectives and possible directions for future development.

Recent advances in the medical applications of hemostatic materials

Bleeding caused by trauma or surgery is a serious health problem, and uncontrollable bleeding can result in death. Therefore, developing safe, effective, and convenient hemostatic materials is important. Active hemostatic agents currently used to investigate the field of hemostasis are divided into four broad categories: natural polymers, synthetic polymers, inorganic materials, and metal-containing materials. Hemostatic materials are prepared in various forms for wound care applications based on the active ingredients used. These materials include nanofibers, gels, sponges, and nanoparticles. Hemostatic materials find their applications in the field of wound care, and they are also used for hemostasis during malignant tumor surgery. Prompt and effective hemostasis can reduce the possibility of the spread of tumor cells with blood. This review discusses the outcomes of current research conducted in the field and the problems persisting in the field of developing hemostatic materials. The review also presents a platform for the further development of hemostatic materials. Bleeding caused by trauma or surgery is a serious health problem, and uncontrollable bleeding can result in death. Therefore, developing safe, effective, and convenient hemostatic materials is important. Active hemostatic agents currently used to investigate the field of hemostasis are divided into four broad categories: natural polymers, synthetic polymers, inorganic materials, and metal-containing materials. Hemostatic materials are prepared in various forms for wound care applications based on the active ingredients used. These materials include nanofibers, gels, sponges, and nanoparticles. Hemostatic materials find their applications in the field of wound care, and they are also used for hemostasis during malignant tumor surgery. Prompt and effective hemostasis can reduce the possibility of the spread of tumor cells with blood. This review discusses the outcomes of current research conducted in the field and the problems persisting in the field of developing hemostatic materials. The review also presents a platform for the further development of hemostatic materials.

Design of biopolymer-based hemostatic material: Starting from molecular structures and forms

Uncontrolled bleeding remains as a leading cause of death in surgical, traumatic, and emergency situations. Management of the hemorrhage and development of hemostatic materials are paramount for patient survival. Owing to their inherent biocompatibility, biodegradability and bioactivity, biopolymers such as polysaccharides and polypeptides have been extensively researched and become a focus for the development of next-generation hemostatic materials. The construction of novel hemostatic materials requires in-depth understanding of the physiological hemostatic process, fundamental hemostatic mechanisms, and the effects of material chemistry/physics. Herein, we have recapitulated the common hemostatic strategies and development status of biopolymer-based hemostatic materials. Furthermore, the hemostatic mechanisms of various molecular structures (components and chemical modifications) are summarized from a microscopic perspective, and the design based on them are introduced. From a macroscopic perspective, the design of various forms of hemostatic materials, e.g., powder, sponge, hydrogel and gauze, is summarized and compared, which may provide an enlightenment for the optimization of hemostat design. It has also highlighted current challenges to the development of biopolymer-based hemostatic materials and proposed future directions in chemistry design, advanced form and clinical application.

Development of Biodegradable Osteopromotive Citrate-Based Bone Putty

The burden of bone fractures demands development of effective biomaterial solutions, while additional acute events such as noncompressible bleeding further motivate the search for multi-functional implants to avoid complications including osseous hemorrhage, infection, and nonunion. Bone wax has been widely used in orthopedic bleeding control due to its simplicity of use and conformation to irregular defects; however, its nondegradability results in impaired bone healing, risk of infection, and significant inflammatory responses. Herein, a class of intrinsically fluorescent, osteopromotive citrate-based polymer/hydroxyapatite (HA) composites (BPLP-Ser/HA) as a highly malleable press-fit putty is designed. BPLP-Ser/HA putty displays mechanics replicating early nonmineralized bone (initial moduli from ≈2-500 kPa), hydration induced mechanical strengthening in physiological conditions, tunable degradation rates (over 2 months), low swelling ratios (<10%), clotting and hemostatic sealing potential (resistant to blood pressure for >24 h) and significant adhesion to bone (≈350-550 kPa). Simultaneously, citrate's bioactive properties result in antimicrobial (≈100% and 55% inhibition of S. aureus and E. coli) and osteopromotive effects. Finally, BPLP-Ser/HA putty demonstrates in vivo regeneration in a critical-sized rat calvaria model equivalent to gold standard autograft. BPLP-Ser/HA putty represents a simple, off-the-shelf solution to the combined challenges of acute wound management and subsequent bone regeneration.

Cellulose-Based Cryogel Microspheres with Nanoporous and Controllable Wrinkled Morphologies for Rapid Hemostasis

First-aid hemostatic agents for acute bleeding can save lives in emergency situations. However, rapid hemostasis remains challenging when uncontrolled hemorrhage occurs on lethal noncompressible and irregular wounds. Herein, cellulose-based cryogel microspheres with deliberately customized micromorphologies for ultrafast water transportation and diffusion, including the shark skin riblet-inspired wrinkled surface with low fluid drag and the hydrophilic nanoporous 3D networks, are developed to deal with the acute noncompressible bleeding within seconds. These cryogel microspheres can rapidly absorb a large amount of blood over 6 times their own weight in 10 s and form a robust barrier to seal a bleeding wound without applying pressure. Remarkably, massive bleeding from a cardiac penetrating hole is effectively stopped using the microspheres within 20 s and no blood leakage is observed after 30 min. Additionally, these microspheres could be readily removed without rebleeding and capillary thrombus, which is highly favorable to rapid hemostasis in emergency rescue.

Dual drug delivery system of teicoplanin and phenamil based on pH-sensitive silk fibroin/sodium alginate hydrogel scaffold for treating chronic bone infection

For effective treatment of infected bone, it is essential to use local drug delivery systems with the ability to deliver both antibiotics and osteoinductive factors. Herein, a pH-sensitive silk fibroin (SF)/sodium alginate (SA) hydrogel scaffolds containing teicoplanin (TEC) and phenamil (PM) loaded SF nanoparticles (PMSFNPS) are introduced for treating chronic osteomyelitis. The TEC and PM showed a sustained- and pH-sensitive release behavior from SF/SA hydrogel. The higher release rate was seen in an alkaline pH in comparison to neutral and acidic pH during 10 days. The eluted TEC maintained its antibacterial activity of >75 % during 35 days and in three different pH values (5.5, 7.4, and 8.5). The cellular study indicated that the scaffolds containing PMSFNPs could promote the cell viability, ALP activity, and matrix mineralization. Moreover, the in vivo effectiveness of hydrogel scaffolds were analyzed with radiography, histological and Immunohistochemistry evaluations. The lower infection and higher regeneration were observed in methicillin-resistant Staphylococcus aureus (MRSA) infected rat bone treated with hydrogel scaffold containing PMSFNPs and TEC compared to other groups. Consequently, this dual-drug delivery system could be a hopeful approach for effective treatment of chronic bone infection.

Engineered Hemostatic Biomaterials for Sealing Wounds

Hemostatic biomaterials show great promise in wound control for the treatment of uncontrolled bleeding associated with damaged tissues, traumatic wounds, and surgical incisions. A surge of interest has been directed at boosting hemostatic properties of bioactive materials via mechanisms triggering the coagulation cascade. A wide variety of biocompatible and biodegradable materials has been applied to the design of hemostatic platforms for rapid blood coagulation. Recent trends in the design of hemostatic agents emphasize chemical conjugation of charged moieties to biomacromolecules, physical incorporation of blood-coagulating agents in biomaterials systems, and superabsorbing materials in either dry (foams) or wet (hydrogel) states. In addition, tough bioadhesives are emerging for efficient and physical sealing of incisions. In this Review, we highlight the biomacromolecular design approaches adopted to develop hemostatic bioactive materials. We discuss the mechanistic pathways of hemostasis along with the current standard experimental procedures for characterization of the hemostasis efficacy. Finally, we discuss the potential for clinical translation of hemostatic technologies, future trends, and research opportunities for the development of next-generation surgical materials with hemostatic properties for wound management.

Nanoengineered Neutrophils as a Cellular Sonosensitizer for Visual Sonodynamic Therapy of Malignant Tumors

The rapid evolution of cell-based theranostics has attracted extensive attention due to their unique advantages in biomedical applications. However, the inherent functions of cells alone cannot meet the needs of malignant tumor treatment. Thus endowing original cells with new characteristics to generate multifunctional living cells may hold a tremendous promise. Here, the nanoengineering method is used to combine customized liposomes with neutrophils, generating oxygen-carrying sonosensitizer cells with acoustic functions, which are called Acouscyte/O₂ , for the visual diagnosis and treatment of cancer. Specifically, oxygen-carried perfluorocarbon and temoporfin are encapsulated into cRGD peptide modified multilayer liposomes (C-ML/HPT/O₂ ), which are then loaded into live neutrophils to obtain Acouscyte/O₂ . Acouscyte/O₂ can not only carry a large amount of oxygen but also exhibits the ability of long circulation, inflammation-triggered recruitment, and decomposition. Importantly, Acouscyte/O₂ can be selectively accumulated in tumors, effectively enhancing tumor oxygen levels, and triggering anticancer sonodynamics in response to ultrasound stimulation, leading to complete obliteration of tumors and efficient extension of the survival time of tumor-bearing mice with minimal systemic adverse effects. Meanwhile, the tumors can be monitored in real time by temoporfin-mediated fluorescence imaging and perfluorocarbon (PFC)-microbubble-enhanced ultrasound imaging. Therefore, the nanoengineered neutrophils, i.e., Acouscyte/O₂ , are a new type of multifunctional cellular drug, which provides a new platform for the diagnosis and sonodynamic therapy of solid malignant tumors.

Biomaterials for Hemostasis

Uncontrolled bleeding is a major problem in trauma and emergency medicine. While materials for trauma applications would certainly find utility in traditional surgical settings, the unique environment of emergency medicine introduces additional design considerations, including the need for materials that are easily deployed in austere environments. Ideally, these materials would be available off the shelf, could be easily transported, and would be able to be stored at room temperature for some amount of time. Both natural and synthetic materials have been explored for the development of hemostatic materials. This review article provides an overview of classes of materials used for topical hemostats and newer developments in the area of injectable hemostats for use in emergency medicine. Expected final online publication date for the Annual Review of Biomedical Engineering, Volume 24 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Recent advances in materials for hemostatic management

Traumatic hemorrhage can be a fatal event, particularly when large quantities of blood are lost in a short period of time. Therefore, hemostasis has become a crucial part of emergency treatment. For small wounds, hemostasis can be achieved intrinsically depending on the body's own blood coagulation mechanism; however, for large-area wounds, particularly battlefield and complex wounds, materials delivering rapid and effective hemostasis are required. In parallel with the constant progress in science, technology, and society, advances in hemostatic materials have also undergone various iterations by integrating new ideas with old concepts. There are various natural and synthetic hemostatic materials, including hemostatic powders, adhesives, hydrogels, and tourniquets, for the treatment of severe external trauma. This review covers the differences among the currently available hemostatic materials and comprehensively describes the hemostatic effects of different materials based on the underlying mechanisms. Finally, solutions for current issues related to trauma bleeding are discussed, and the prospects of hemostatic materials are proposed.

Construction of hollow polydopamine nanoparticle based drug sustainable release system and its application in bone regeneration

Nanomaterial-based drug sustainable release systems have been tentatively applied to bone regeneration. They, however, still face disadvantages of high toxicity, low biocompatibility, and low drug-load capacity. In view of the low toxicity and high biocompatibility of polymer nanomaterials and the excellent load capacity of hollow nanomaterials with high specific surface area, we evaluated the hollow polydopamine nanoparticles (HPDA NPs), in order to find an optimal system to effectively deliver the osteogenic drugs to improve treatment of bone defect. Data demonstrated that the HPDA NPs synthesized herein could efficiently load four types of osteogenic drugs and the drugs can effectively release from the HPDA NPs for a relatively longer time in vitro and in vivo with low toxicity and high biocompatibility. Results of qRT-PCR, ALP, and alizarin red S staining showed that drugs released from the HPDA NPs could promote osteogenic differentiation and proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. Image data from micro-CT and H&E staining showed that all four osteogenic drugs released from the HPDA NPs effectively promoted bone regeneration in the defect of tooth extraction fossa in vivo, especially tacrolimus. These results suggest that the HPDA NPs, the biodegradable hollow polymer nanoparticles with high drug load rate and sustainable release ability, have good prospect to treat the bone defect in future clinical practice.

Facile and green approach towards biomass-derived hydrogel powders with hierarchical micro-nanostructures for ultrafast hemostasis

Although a series of biomass-derived hemostats has been developed, the desire for green-prepared hemostatic materials with biosafety has not decreased. Herein, we constructed porous carboxymethyl chitosan/sodium alginate/Ca(OH)₂ powders (PCSCPs) with suitable adaptability for instant control of irregular hemorrhage via a facile and green approach. By one-pot chemical crosslinking of carboxymethyl chitosan and sodium alginate, hydrogels were formed and immediately ionically cross-linked along with the generation of Ca(OH)₂ to prepare PCSCPs. As hydrogel powders, PCSCPs with abundant hydrophilic carboxymethyl groups and porous hierarchically micro-nanostructures displayed a high water absorption ratio of over 1600%. The PCSCPs were confirmed with favorable hemocompatibility, non-cytotoxic effects and excellent degradability. Hemostasis assays in vitro showed that PCSCPs possessed an outstanding property of platelet activation and red blood cell aggregation. The PCSCPs effectively shortened the hemostatic time and blood loss to ca. 50% in rodent bleeding models compared with medical gauze and commercial chitosan-based hemostats. Furthermore, a mouse subcutaneous implantation model demonstrated an ignorable inflammation response and potential tissue repair capability of PCSCPs. It's believed that green-prepared and biomass-derived PCSCPs are feasible biomedical hemostatic materials in view of engineering and provide a promising platform to design hemostats in prehospital management and clinical settings.

Modified porous carboxymethyl chitin microspheres by an organic solvent-free process for rapid hemostasis

Rapid and effective hemorrhage control is essential to reduce mortality following traumatic injuries. Herein we developed an organic solvent-free process to prepare carboxymethyl chitin microsphere (CMCHm) in an aqueous two-phase system through heating and freeze-drying. To further enhance the hemostatic performance of CMCHm, we loaded calcium ions and in-situ polymerized dopamine to get modified hemostatic microspheres CMCHm-Ca²⁺ and CMCHm-PDA, respectively. The size of these microspheres was mainly distributed between 50 μm and 150 μm, and the porous microstructure was observed by SEM. The data of in vitro degradation, cell cytotoxicity, and hemolysis test indicated good biocompatibility of these microspheres. Importantly, CMCHm-Ca²⁺ and CMCHm-PDA displayed better hemostatic performance compared with CMCHm and the positive controls Yunnan baiyao® and Quickclean®. Especially, the bleeding time was reduced to 59 s (CMCHm-Ca²⁺) and 45 s (CMCHm-PDA) in the femoral artery/vein cut model, respectively. All these demonstrate CMCHm-Ca²⁺ and CMCHm-PDA hold great potential for rapid hemostasis.

Ultrafast Fabrication of Self-Healing and Injectable Carboxymethyl Chitosan Hydrogel Dressing for Wound Healing

Herein, a new type of injectable carboxymethyl chitosan (CMCh) hydrogel wound dressing with self-healing properties is constructed. First, CMCh samples are homogeneously synthesized in alkali/urea aqueous solutions. Subsequently, trivalent metal ions of Fe³⁺ and Al³⁺ are introduced to form coordination bonds with CMCh, leading to an ultrafast gelation process. A series of hydrogels can be obtained by altering the concentration of CMCh and the relative content of metal ions. Owing to the dynamic and reversible characteristics of the coordination bonds, the hydrogel exhibits self-healing, self-adaption, and thermoresponsive ability. Moreover, due to the interaction between the amino groups on CMCh and SO₄^2-, the hydrogel undergoes phase separation and can be painlessly detached from the skin with little residue. Taking advantage of all these characteristics, the hydrogel is used as a wound dressing and can significantly accelerate skin tissue regeneration and wound closure. This hydrogel has great potential in the application of tissue engineering.