Experimental and Modelling Study of Controlled Release from Dextran-Based Cryogels.

In this work, five different dextran-based cryogels for controlled drug release are investigated. Vitamin B12 was used as a model drug for in vitro release tests. Two different drug-loading procedures were adopted, leading to very different drug release curves. Indeed, a fast Fickian release was observed when freeze-dried samples of DEX40PEG360MA and DEX40PEG500MA were infused with the drug after cryogel formation. On the contrary, a slowed highly non-Fickian behavior arises when the drug is loaded before the low-temperature crosslinking step, leading to the cryogel formation. The non-Fickian drug release, observed for all the five different dextran-based cryogels investigated, is actually due to the cryoconcentration phenomenon, modeled with a two-step release process. The proposed transport model accurately predicts experimental release curves characterized by a long lag time, confirming that dextran-based cryogels are suitable for controlled release.

Agarose Cryogels Loaded with Polydopamine Microspheres for Sustainable Wound Care with Enhanced Hemostatic and Antioxidant Properties.

Excessive bleeding presents a grave risk to life, especially in scenarios involving deep wounds such as those inflicted by gunshots and accidental stabs. Despite advancements in wound care management, existing commercial hemostatic agents have limitations, necessitating the development of enhanced solutions. In this study, we developed cryogels using agarose and polydopamine microspheres as a hemostatic dressing to effectively manage profuse bleeding. The resulting cryogels demonstrated impressive attributes, such as high absorption capacity (>4000%), shape recovery ability, antioxidant properties, and excellent biocompatibility in mammalian cell lines. Particularly noteworthy was the rapid blood clotting observed in vitro, with the agarose/PDA cryogels achieving complete clotting within just 90 s. Subsequent validation in the rat trauma model further underscored their hemostatic efficacy, with clotting times of 40 and 53 s recorded in tail amputation and liver puncture models, respectively. The porous structure and hydrophilicity of the cryogels facilitated superior blood absorption and retention, while the amine groups of polydopamine played a pivotal role in enhancing blood clotting activity. This study represents a significant step forward in utilizing agarose/polydopamine cryogels as advanced materials for hemostatic wound dressings, promising an impactful contribution to wound therapy.

Cryogels Composites: Recent Improvement in Bone Tissue Engineering.

Autogenous bone grafts have long been considered the optimal choice for bone reconstruction due to their excellent biocompatibility and osteogenic properties. However, their limited availability and associated donor site morbidity have led to exploration of alternative bone substitutes. Cryogels, with their interconnected porosity, shape recovery, and enhanced mass transport capabilities, have emerged as a promising polymer-based solution. By incorporating bioactive glasses and nanofillers, cryogel composites offer bioactivity, cost-efficiency, and easy cell integration. This approach not only enhances bone regeneration but also underscores the broader role of nanotechnology in regenerative medicine. This mini-review discusses the advancement of organic-inorganic composites, focusing on biopolymeric cryogels and inorganic elements for reinforcement. We highlight how cryogels can be integrated into minimally invasive procedures, reducing patient distress and complications, and advanced 3D-printing techniques that enable further customization of these materials to mimic bone tissue architecture, offering potential for patient-specific treatments.

Deep Cleaning of Crystal Violet and Methylene Blue Dyes from Aqueous Solution by Dextran-Based Cryogel Adsorbents.

Polysaccharides have recently attracted growing attention as adsorbents for various pollutants, since they can be extracted from a variety of renewable sources at low cost. An interesting hydrophilic and biodegradable polysaccharide is dextran (Dx), which is well-known for its applications in the food industry and in medicine. To extend the application range of this biopolymer, in this study, we investigated the removal of crystal violet (CV) and methylene blue (MB) dyes from an aqueous solution by Dx-based cryogels using the batch technique. The cryogel adsorbents, consisting of cross-linked Dx embedding a polyphenolic (PF) extract of spruce bark, were prepared by the freeze-thawing approach. It was shown that the incorporation of PF into the Dx-based matrix induced a decrease in porosity, pore sizes and swelling ratio values. Moreover, the average pore sizes of the DxPF cryogels loaded with dyes further decreased from 42.30 ± 7.96 µm to 23.68 ± 2.69 µm, indicating a strong interaction between the functional groups of the cryogel matrix and those of the dye molecules. The sorption performances of the DxPF adsorbents were evaluated in comparison to those of the Dx cryogels and of the PF extract. The experimental sorption capacities of the DxPF cryogel adsorbents were higher in comparison to those of the Dx cryogels and the PF extract. The DxPF cryogels, particularly those with the highest PF contents (sample DxPF2), demonstrated sorption capacities of 1.2779 ± 0.0703 mmol·g-1, for CV, and 0.3238 ± 0.0121 mmol·g-1, for MB. The sorption mechanisms were analyzed using mathematical models, including Langmuir, Freundlich, Sips and Dubinin-Radushkevich isotherms, and kinetic models, like pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD). The sorption process was best described by the Sips isotherm and PSO kinetic models, indicating chemisorption as the dominant mechanism. This study outlines the importance of developing advanced renewable materials for environmental applications.

Tailoring the structural and physicochemical properties of rice straw cellulose-based cryogels by cell-mediated polyhydroxyalkanoate deposition.

This study presents a novel biotechnological approach for creating water vapor-resistant cryogels with improved integrity. Rice straw cellulose was transformed into nanofibrils through TEMPO-mediated oxidation and high-pressure homogenization. The resulting cryogels remained firm even when immersed in aqueous media, whose pores were used by live cell to deposit polyhydroxyalkanoate (PHA) particles inside them. This novel method allowed the compatibilization of PHA within the cellulosic fibers. As a consequence, the water sorption capacity was decreased by up to 6 times having just 4 % of PHA compared to untreated cryogels, preserving the cryogel density and elasticity. Additionally, this technique can be adapted to various bacterial strains and PHA types, allowing for further optimization. It was demonstrated that the amount and type of PHA (medium chain length and small chain length-PHA) used affects the properties for the cryogels, especially the water vapor sorption behavior and the compressive strength. Compared to traditional coating methods, this cell-mediated approach not only allows to distribute PHA on the surface of the cryogel, but also ensures polymer penetration throughout the cryogel due to bacterial self-movement. This study opens doors for creating cryogels with tunable water vapor sorption and other additional functionalities through the use of specialized PHA variants.

Preparation of ultra-light, highly compressible, and biodegradable chitosan porous materials for heavy metal adsorption, dye adsorption and oil-water separation.

Chitosan materials are much important in adsorption, separation and water treatment due to their hydrophilicity, biodegradability and easy functionalization. However, they were difficult to form structural materials, which limited its application in engineering. In this paper, a new type of chitosan porous materials was prepared with two-step strategy involving the freezing crosslinking of chitosan with glutaraldehyde to form cryogels, and their subsequent reduction with NaBH4 to transform CN bonds into CN bonds, resulting in remarkable improvement of mechanical property. That is, the strength remained almost unchanged after 80 % deformation. The abundant -NH2 and -OH on the surface of materials, as well as the unique pore structure from cryogels, gave relatively high adsorption capacity for metals and dyes (88.73 ± 4.25 mg·g-1 for Cu(II) and 3261.05 ± 36.10 mg·g-1 for Congo red). The surface hydrophilicity of materials made it possible for selective water permeation with over 95 % separation efficiency for oil-water mixtures. In addition, simple hydrophobic modification using bromotetradecane achieved selective oil permeation with over 96 % separation efficiency for oil-water mixtures. This study not only provides a new strategy to endow chitosan materials with excellent mechanical property, large adsorption capacity and good oil-water separation performance, but also offers environmentally friendly materials for sewage treatment applications.

Implementation of a Macroporous Polyhydroxyethylmethacrylate Cryogel-Based Mini-Bioreactor System to Improve Monoclonal Antibody Production.

BACKGROUND: Monoclonal antibodies (mAbs) are pioneers in the diagnosis and treatment of many diseases, such as cancer, asthma, poisoning, viral infections, etc. As the market value of mAbs increases in the biopharma industry, the demand for high quantities is met by upscaled production using bioreactor systems. Thus, disposable, porous matrices called cryogels have gained the primary focus for adherent support in the proliferation of hybridoma cells. METHODS: In this study, a gelatin-immobilized polyhydroxyethylmethacrylate-based cryogel material (disc-shaped, 9 mL bed volume) was synthesized, and a mini-bioreactor set up developed for culturing hybridoma cells to produce mAbs continuously. The hybridoma clone, 1B4A2D5, secreting anti-human serum albumin monoclonal antibodies, was immobilized in the cryogel matrix (2 discs, 18 mL bed volume). RESULTS: The hybridoma cells were attached to the matrix within 12 h after inoculation, and the cells were in the lag phase for seven days, where they were secreted mAb into the circulation medium. During the initial exponential phase, the glucose consumption, lactic acid production, and mAb production were 3.36 mM/day, 3.67 mM/day, and 55.61 µg/mL/day, respectively. The medium was refreshed whenever the glucose in the media went below 50% of the initial glucose concentration. The cryogenic reactor was run continuously for 25 days, and the mAb concentration reached a maximum on the 17th day at 310.59 µg/mL. CONCLUSION: The cumulative amount of mAbs produced in 25 days of running was 246 µg/mL, 7.7 times higher than the mAbs produced from T-flask batch cultivation. These results demonstrate that the developed polyhydroxyethylmethacrylate-based cryogel reactor can be used efficiently for continuous mAb production.

Copper-MOF and tannic acid-empowered composite cryogel as a skin substitute for accelerated deep wound healing.

The effective management of deep skin wounds remains a significant healthcare challenge that often deteriorates with bacterial infection, oxidative stress, tissue necrosis, and excessive production of wound exudate. Current medical approaches, including traditional wound dressing materials, cannot effectively address these issues. There is a great need to engineer advanced and multifunctional wound dressings to address this multifaceted problem effectively. Herein, a rationally designed composite cryogel composed of a Copper Metal-Organic Framework (Cu-MOF), tannic acid (TA), polyvinyl alcohol (PVA), and zein protein has been developed by freeze-thaw technique. Cryogels display a remarkable swelling capacity attributed to their interconnected microporous morphology. Moreover, dynamic mechanical behaviour with the characteristics of potent antimicrobial, antioxidant, and biodegradation makes it a desirable wound dressing material. It was further confirmed that the material is highly biocompatible and can release TA and copper ions in a controlled manner. In-vivo skin irritation in a rat model demonstrated that composite cryogel did not provoke any irritation/inflammation when applied to the skin of a healthy recipient. In a deep wound model, the composite cryogel significantly accelerates the wound healing rate. These findings highlight the multifunctional nature of composite cryogels and their promising potential for clinical applications as advanced wound dressings.

Macroporous PEG-Alginate Hybrid Double-Network Cryogels with Tunable Degradation Rates Prepared via Radical-Free Cross-Linking for Cartilage Tissue Engineering.

Trauma or repeated damage to joints can result in focal cartilage defects, significantly elevating the risk of osteoarthritis. Damaged cartilage has an inherently limited self-healing capacity and remains an urgent unmet clinical need. Consequently, there is growing interest in biodegradable hydrogels as potential scaffolds for the repair or reconstruction of cartilage defects. Here, we developed a biodegradable and macroporous hybrid double-network (DN) cryogel by combining two independently cross-linked networks of multiarm polyethylene glycol (PEG) acrylate and alginate.Hybrid DN cryogels are formed using highly biocompatible click reactions for the PEG network and ionic bonding for the alginate network. By judicious selection of various structurally similar cross-linkers to form the PEG network, we can generate hybrid DN cryogels with customizable degradation kinetics. The resulting PEG-alginate hybrid DN cryogels have an interconnected macroporous structure, high mechanical strength, and rapid swelling kinetics. The interconnected macropores in the cryogels support efficient mesenchymal stem cell infiltration at a high density. Finally, we demonstrate that PEG-alginate hybrid DN cryogels allow sustained release of chondrogenic growth factors and support chondrogenic differentiation of mouse mesenchymal stem cells. This study provides a novel method to generate macroporous hybrid DN cryogels with customizable degradation rates and a potential scaffold for cartilage tissue engineering.

Arginine-loaded globular BSAMA/fibrous GelMA biohybrid cryogels with multifunctional features and enhanced healing for soft gingival tissue regeneration.

Mucogingival surgery has been widely used in soft gingival tissue augmentation in which autografts are predominantly employed. However, the autografts face grand challenges, such as scarcity of palatal donor tissue and postoperative discomfort. Therefore, development of alternative soft tissue substitutes has been an imperative need. Here, we engineered an interconnected porous bovine serum albumin methacryloyl (BSAMA: B, as a drug carrier and antioxidant)/gelatin methacryloyl (GelMA: G, as a biocompatible collagen-like component)-based cryogel with L-Arginine (Arg) loaded as an angiogenic molecule, which could serve as a promising gingival tissue biohybrid scaffold. BG@Arg cryogels featured macroporous architecture, biodegradation, sponge-like properties, suturability, and sustained Arg release. Moreover, BG@Arg cryogels promoted vessel formation and collagen deposition which play an important role in tissue regeneration. Most interestingly, BG@Arg cryogels were found to enhance antioxidant effects. Finally, the therapeutic effect of BG@Arg on promoting tissue regeneration was confirmed in rat full-thickness skin and oral gingival defect models. In vivo results revealed that BG@Arg2 could promote better angiogenesis, more collagen production, and better modulation of inflammation, as compared to a commercial collagen membrane. These advantages might render BG@Arg cryogels a promising alternative to commercial collagen membrane products and possibly autografts for soft gingival tissue regeneration.

Specific DNA aptamer-immobilized cryogel membranes as novel bioaffinity supports and their potential for the purification of activated protein C.

Activated protein C (APC), a serine protease produced from zymogen protein C (PC), is the key enzyme of the protein C pathway. APC has anticoagulant, anti-inflammatory, and cytoprotective features. APC has recently been shown to significantly reduce coagulation as well as mortality in patients with severe sepsis. Herein, we aimed to develop an affinity support material that allows the purification of plasma APC for the first time. In this research, a novel APC-specific DNA aptamer-based poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA/DNA-Apt)) macroporous cryogel membrane at different molar ratios was prepared using affinity binding method and their potential for purification and identification of APC was investigated. The DNA aptamer-immobilized cryogels were characterized to examine their structural and morphological properties. The effect of pH, initial concentration, temperature, ionic strength difference, and flow rate changes was examined. Selectivity studies were performed in the presence of APC and competitive proteins, and cryogel support materials were shown to have a very high affinity for APC. Adsorption capacity was found to be 89.02 mg/g. Finally, NaCl revealed efficiency for APC desorption and the reuse of cryogels was successfully tested for ten cycles.

Variable-transmittance bio-based phase change composites based on the photothermal property of pectin.

In this study, the possibility of using a natural polysaccharide, pectin, in a novel function as a photothermal material was investigated by fabricating a Pectin/Polyethylene glycol (PEG)/Poly(methyl methacrylate) (PMMA) composite via the infiltration of PEG/PMMA polymer mixture into freeze-casted pectin cryogel template. The Pectin/PEG/PMMA composite has high latent heat of 48 J/g, excellent UV blocking ability, and tailorable transmittance as well as capacity to energy storage via photothermal heating to the melting point of PEG under sunlight. The photothermal effect can be enhanced with the increase of pectin concentration and irradiation intensity. Furthermore, by using the Pectin/PEG/PMMA composite as a window of a model house could effectively reduce the temperature rise inside the house under irradiation and reduce the temperature drop after turning off the irradiation, as compared to a model house with conventional glass as the window material. Therefore, this work provides a new application of pectin as photothermal material and opens the opportunity to develop novel sustainable bio-based photothermal materials.

Characterization of gelatin-oxidized riclin cryogels and their applications as reusable ice cubes in shrimp preservation.

Traditional ice is usually employed to preserve food freshness and extend shelf life. However, ice cannot bear repeated freeze - thaw cycles during the transportation and retailing process, resulting in microbial cross-contamination and spoilage of foods. Herein, succinoglycan riclin was oxidated (RO) and crosslinked with gelatin (Ge), the Ge-RO cryogels were prepared via Schiff base reaction and three freeze - thaw cycles. The Ge-RO cryogels showed improved storage modulus (G') and thermal stability compared with pure gelatin hydrogel. The polymer framework of Ge-RO gels exhibited stable properties against ice crystals destructions during nine freeze - thaw treatments. During the storage and repeated freeze - thaw treatments of shrimps, Ge-RO cryogels exhibited a remarkable preservation effect on shrimps, and their freshness was evaluated using an electronic nose technique equipped with ten sensors. The results demonstrated that the shrimp muscle preserved in ice generated off-odors and resulted in high sensor responses. The sensor responses were reduced sharply of shrimps preserved in cryogels. Moreover, 1H NMR-based metabolomics analysis revealed that shrimps in Ge-RO cryogels group reversed the metabolic perturbations compared with the traditional ice group, the metabolic pathways were related to energy metabolism, nucleotide metabolism, and amino acid metabolism, which provide new clues to the freshness of shrimps. Furthermore, RO exhibited superior antimicrobial activity against E. coli and S. aureus microorganisms. Thus, the crosslinked cryogels are potentially applicable to food preservation, offering sustainable and reusable solutions against traditional ice.

Chitosan-Alginate Gels for Sorption of Hazardous Materials: The Effect of Chemical Composition and Physical State.

Chitosan, alginate, and chitosan-alginate (50:50) mixed hydrogels were prepared by freeze casting, freeze-drying, and subsequent physical cross-linking. Chitosan was cross-linked with citrate and alginate with calcium ions, while the mixed gels were cross-linked with both cross-linking agents. Both cryogels and xerogels were obtained by lyophilization and drying of the hydrogels. We investigated the effect of the chemical composition and the physical state of gels on the gel structure and sorption of model dyes. Alginate and mixed gels cross-linked with Ca2+ ions sorbed 80-95% of cationic dye from the solutions. The chitosan gels are primarily capable of adsorbing anionic dyes, but at near-neutral pH, their capacity is lower than that of alginate gels, showing 50-60% dye sorption. In the case of alginate gels, the dye sorption capacity of xerogels, cryogels, and hydrogels was the same, but for chitosan gels, the hydrogels adsorbed slightly less dye than the dried gels.

Antimicrobial starch-based cryogels and hydrogels for dual-active food packaging applications.

The present study reports on the valorisation of starch waste biomass to produce dual-active cryogels and hydrogels able to adsorb water and deliver antimicrobial substances for fresh food packaging applications. Starch hydrogels were prepared by oxidation with sodium metaperiodate in water and mild conditions, while cryogels were obtained by freeze-drying process. To explore the role of starch composition on the final properties of materials, two starches differing in amylose/amylopectin ratio, were evaluated. The prepared materials were microstructurally and morphologically characterized by FTIR and NMR spectroscopy (1D, 2D, and DOSY experiments), and SEM microscopy. To provide the materials with active properties, they were loaded with antimicrobial molecules by absorption, or by crosslinking via Schiff-base reaction. All materials demonstrated high water absorption capacity and ability to deliver volatile molecules, including diacetyl and complex mixtures like mint essential oil. The release profiles of the adsorbed molecules were determined through quantitative NMR spectroscopy over time. The antibacterial activity was successfully demonstrated against Gram-positive bacterial strains for unloaded cryogels and hydrogels, and after loading with diacetyl and essential oil. The developed materials can be regarded as part of active pads for food packaging applications capable to control moisture inside the package and inhibit microbial contamination.

Impact of Composition and Autoclave Sterilization on the Mechanical and Biological Properties of ECM-Mimicking Cryogels.

Cryogels represent a valid strategy as scaffolds for tissue engineering. In order to adequately support adhesion and proliferation of anchorage-dependent cells, different polymers need to be combined within the same scaffold trying to mimic the complex features of a natural extracellular matrix (ECM). For this reason, in this work, gelatin (Gel) and chondroitin sulfate (CS), both functionalized with methacrylic groups to produce CSMA and GelMA derivatives, were selected to prepare cryogel networks. Both homopolymer and heteropolymer cryogels were produced, via radical crosslinking reactions carried out at -12 °C for 2 h. All the scaffolds were characterized for their mechanical, swelling and morphological properties, before and after autoclave sterilization. Moreover, they were evaluated for their biocompatibility and ability to support the adhesion of human gingival fibroblasts and tenocytes. GelMA-based homopolymer networks better withstood the autoclave sterilization process, compared to CSMA cryogels. Indeed, GelMA cryogels showed a decrease in stiffness of approximately 30%, whereas CSMA cryogels of approximately 80%. When GelMA and CSMA were blended in the same network, an intermediate outcome was observed. However, the hybrid scaffolds showed a general worsening of the biological performance. Indeed, despite their ability to withstand autoclave sterilization with limited modification of the mechanical and morphological properties, the hybrid cryogels exhibited poor cell adhesion and high LDH leakage. Therefore, not only do network components need to be properly selected, but also their combination and ability to withstand effective sterilization process should be carefully evaluated for the development of efficient scaffolds designed for tissue engineering purposes.

An Acellular, Self-Healed Trilayer Cryogel for Osteochondral Regeneration in Rabbits.

Osteochondral regeneration remains formidable challenges despite significant advances in microsurgery. Herein, an acellular trilayer cryogel (TC) with injectability, tunable pore sizes (80-200 µm), and appropriate compressive modulus (10.8 kPa) is manufactured from self-healable hydrogel under different gelling times through Schiff reaction between chitosan and difunctionalized polyurethane (DFPU). Bioactive molecules (Y27632 and dexamethasone) are respectively loaded in the top and bottom layers to form the Y27632/dexamethasone-loaded trilayer cryogel (Y/DEX-TC). Mesenchymal stem cells (MSCs) seeded in Y/DEX-TC proliferated ≈350% in vitro and underwent chondrogenesis or osteogenesis in response to the respective release of Y or DEX in 14 days. Acupuncture is administered to animals in an attempt to modulate the innate regulatory system and mobilize endogenous MSCs for osteochondral defect regeneration. In vivo rabbit experiments using Y/DEX-TC combined with acupuncture successfully regulate SDF-1 and TGF-ß1 levels, which possibly cause MSC migration toward Y/DEX-TC. The synergistic effect of cryogel and acupuncture on immunomodulation is verified with a ≈7.3-fold enhancement of the M2-/M1-macrophage population ratio by treatment of Y/DEX-TC combining acupuncture, significantly greater than ≈1.5-fold increase by acupuncture or ≈2.2-fold increase by Y/DEX-TC alone. This novel strategy using acellular drug-loaded cryogel and accessible acupuncture shows promise in treating osteochondral defects of joint damage.

HEMA-Lysine-Based Cryogels for Highly Selective Heparin Neutralization.

Unfractionated heparin (UFH) and its low-molecular-weight fragments (LMWH) are widely used as anticoagulants for surgical procedures and extracorporeal blood purification therapies such as cardiovascular surgery and dialysis. The anticoagulant effect of heparin is essential for the optimal execution of extracorporeal blood circulation. However, at the end of these procedures, to avoid the risk of bleeding, it is necessary to neutralize it. Currently, the only antidote for heparin neutralization is protamine sulphate, a highly basic protein which constitutes a further source of serious side events and is ineffective in neutralizing LMWH. Furthermore, dialysis patients, due to the routine administration of heparin, often experience serious adverse effects, among which HIT (heparin-induced thrombocytopenia) is one of the most severe. For this reason, the finding of new heparin antagonists or alternative methods for heparin removal from blood is of great interest. Here, we describe the synthesis and characterization of a set of biocompatible macroporous cryogels based on poly(2-hydroxyethyl methacrylate) (pHEMA) and L-lysine with strong filtering capability and remarkable neutralization performance with regard to UFH and LMWH. These properties could enable the design and creation of a filtering device to rapidly reverse heparin, protecting patients from the harmful consequences of the anticoagulant.

Injectable and rapidly expandable thrombin-decorated cryogels achieve rapid hemostasis and high survival rates in a swine model of lethal junctional hemorrhage.

Effective therapies are urgently needed to stabilize patients with marginally compressible junctional hemorrhage long enough to get them to the hospital alive. Herein, we report injectable and rapidly expandable cryogels consisting of polyacrylamide and thrombin (AT cryogels) created by cryo-polymerization for the efficient management of lethal junctional hemorrhage in swine. The produced cryogels have small pore sizes and highly interconnected porous architecture with robust mechanical strength. The cryogels exhibit rapid shape memory properties and prove to be resilient against fatigue. These cryogels also show high water/blood absorption capacity, fast blood clotting effect, and enhanced adhesion of red blood cells and platelets in vitro. Further, in vivo, hemostatic efficacy tests in a lethal swine junctional hemorrhage model suggest that treatment with AT cryogels, especially AT-2 cryogels, achieves the least blood loss and the highest survival rate (100 %) compared to currently employed products such as XStat® and combat gauze. The high hemostatic performance of the cryogels may be attributed to highly interconnected porous architecture with small pore size and the use of thrombin as a pro-coagulant agent. Collectively, injectable and rapidly expandable thrombin-decorated polyacrylamide-based cryogels show significant promise as hemostatic material, offering effective management of marginally compressible junctional hemorrhages in prehospital settings.

Enhancement of Bone Tissue Regeneration with Multi-Functional Nanoparticles by Coordination of Immune, Osteogenic, and Angiogenic Responses.

Inorganic nanoparticles are promising materials for bone tissue engineering due to their chemical resemblance to the native bone structure. However, most studies are unable to capture the entirety of the defective environment, providing limited bone regenerative abilities. Hence, this study aims to develop a multifunctional nanoparticle to collectively control the defective bone niche, including immune, angiogenic, and osteogenic systems. The nanoparticles, self-assembled by biomimetic mineralization and tannic acid (TA)-mediated metal-polyphenol network (MPN), are released sustainably after the incorporation within a gelatin cryogel. The released nanoparticles display a reduction in M1 macrophages by means of reactive oxygen species (ROS) elimination. Consequently, osteoclast maturation is also reduced, which is observed by the minimal formation of multinucleated cells (0.4%). Furthermore, the proportion of M2 macrophages, osteogenic differentiation, and angiogenic potential are consistently increased by the effects of magnesium from the nanoparticles. This orchestrated control of multiple systems influences the in vivo vascularized bone regeneration in which 80% of the critical-sized bone defect is regenerated with new bones with mature lamellar structure and arteriole-scale micro-vessels. Altogether, this study emphasizes the importance of the coordinated modulation of immune, osteogenic, and angiogenic systems at the bone defect site for robust bone regeneration.