Thrombin immobilized polydopamine-diatom biosilica for effective hemorrhage control

N-succinyl chitosan-oxidized hyaluronic acid-calcium chloride hydrogel as hemostatic agent

This study aims to develop an effective hemostatic agent in the management of irregular and deep wounds that can accelerate the hemostatic process. The background revealed the importance of rapid treatment of bleeding, with data showing a significant risk of death from blood loss. Current treatments use conventional hemostatic dressings, but they are less effective on irregular surgical wounds. Several studies have developed chitosan, hyaluronic acid, and CaCl2-based hydrogels that have hemostatic, regenerative, and antibacterial potential. However, there is still a need to develop hydrogels that are thermally stable, biocompatible, and able to accelerate the hemostatic process. This research will synthesize self-healing hydrogels by modifying the structure of chitosan and hyaluronic acid, using a certain ratio of ingredients. The research procedure was carried out with the preparation of N-succinyl chitosan (NSC) and oxidized hyaluronic acid (OHA) as the main ingredients which were then added with CaCl2 to produce self-healing injectable hydrogel. First, NSC and OHA were dissolved in phosphate buffer solution (pH = 7.4 PBS) to obtain 60 mg/mL NSC and OHA solution respectively. Calcium chloride was then dissolved in water to obtain 120 mg/mL CaCl2 solution. Then NSC-OHA-CaCl2-based hydrogels were synthesized through rapid and full solution mixing above room temperature with the composition of (1-1-0.1; 1-1-0.2; and 1-1-0.3). The targeted findings of this research are sample characterization results that explain and prove the best NSC-OHA-CaCl2 composition variation that can be used as a hemostatic agent for irregular and deep wounds. The results of the analysis obtained FTIR test data with the formation of C = N functional groups in the four samples; blood clotting time test for sample K0, K1, K2, and K3 with time 4.6, 3.33, 2.66, and 1 s; MTT assay with cell viability percentage of 77.82% for sample K0, 84.18% for sample K1, 89.30% for sample K2, and 89.50% for sample K3; hemolysis index percentage of 0.373% for sample K0, 0.555% for sample K1, 0.625% for sample K2, and 0.201% for sample K3; Viscosity test obtained data of 13 dPa s for sample K0, 15 dPa s for sample K1, 16 dPa s for sample K2, and 18 dPa. The injectability test yielded an injectability percentage of 96.84% for sample K0, 95.03% for sample K1, 94.78% dPa s for sample K2, and 94.61% for sample K3; the DSC test results of the four samples obtained a transition peak at the exothermic peak of 62.27°C for sample K0, 70.23°C for sample K1, 73.77°C for sample K2, and 74.49°C for sample K3; and the characteristic graph of the TGA test results, the weight profile of the hydrogel during heating which showed a mass change of 21.64 mg in sample K0, 16.89 mg in sample K1, 15.37 mg in sample K2, and 11.43 mg in sample K3 (°C).

A shape memory cationized chitosan sponge loaded with thrombin for high-effective hemostasis and antibacterial activity

This study presents a thrombin-loaded cationized chitosan (TCCS) sponge with highly effective hemostatic and antibacterial activity. The TCCS sponge, prepared using a multistep method, features a porous structure, favorable mechanical properties, excellent water absorption ability, and shape recovery triggered by water or blood. The TCCS sponge exhibited strong antibacterial activity against Methicillin-resistant Staphylococcus aureus and Escherichia coli. Additionally, it demonstrated enhanced procoagulant and hemostatic efficacy in rat tail amputation and rat liver perforation wound models compared to commercial hemostats. Furthermore, the sponge exhibited favorable biocompatibility and biosafety. These findings suggest that the TCCS sponge has substantial potential for practical applications in managing severe hemorrhages and bacterial infections.

Dual-Responsive Microsphere Based on Natural Sunflower Pollen for Hemostasis and Repair in Inflammatory Bowel Disease

Noninvasive treatment of inflammatory bowel disease with lower gastrointestinal bleeding is a major clinical challenge. In this study, we designed an orally targeted microsphere based on sunflower pollen microcapsules to localize the site of inflammatory injury and promote hemostasis and tissue repair. Due to the Eudragit and ascorbate palmitate coatings, EL/AP@PS(t+Dex) demonstrates pH- and enzyme-responsive release of loaded drugs and helps to resist the harsh environment of the gastrointestinal tract. Both in vitro and in vivo experiments show the characteristics of inflammation targeting and mucosal adhesion, which reduce the systematic exposure and increase the local drug concentration. In the DSS model, orally administered EL/AP@PS(t+Dex) significantly alleviates hematochezia, inhabits intestinal inflammation, and remarkably promotes the recovery of the intestinal epithelial barrier to reduce the exposure of intestinal microvessels. Furthermore, EL/AP@PS(t+Dex) optimized the composition of intestinal microbiota, which benefits intestinal homeostasis. This finding provides a fundamental solution for the treatment of intestinal bleeding caused by inflammatory bowel disease (IBD).

The hemostatic performance and mechanism of palygorskite with structural regulate by oxalic acid gradient leaching

Palygorskite (Pal) is a naturally available one-dimensional clay mineral, featuring rod-shaped morphology, nanoporous structure, permanent negative charges as well as abundant surface hydroxyl groups, exhibiting promising potential as a natural hemostatic material. In this study, the hemostatic performance and mechanisms of Pal were systematically investigated based on the structural regulate induced by oxalic acid (OA) gradient leaching from perspectives of structure, surface attributes and ion release.In vitroandin vivohemostasis evaluation showed that Pal with OA leaching for 1 h exhibited a superior blood procoagulant effect compared with the raw Pal as well as the others leached for prolonging time. This phenomenon might be ascribed to the synergistic effect of the intact nanorod-like morphology, the increase in the surface negative charge, the release of metal ions (Fe3+and Mg2+), and the improved blood affinity, which promoted the intrinsic coagulation pathway, the fibrinogenesis and the adhesion of blood cells, thereby accelerating the formation of robust blood clots. This work is expected to provide experimental and theoretical basis for the construction of hemostatic biomaterials based on clay minerals.

Zinc-mineralized diatom biosilica/hydroxybutyl chitosan composite hydrogel for diabetic chronic wound healing

For sustained and stable improvement of the diabetic wound microenvironment, a temperature-sensitive composite hydrogel (ZnDBs/HBC) composed of inorganic zinc mineralized diatom biosilica (ZnDBs) and hydroxybutyl chitosan (HBC) was developed. The interfacial anchoring effect between ZnDBs and HBC enhanced the mechanical strength of the hydrogel. The mechanical strength of the composite hydrogel containing 3 wt% ZnDBs was increased by nearly 2.3times. The hydrogel can be used as a carrier for sustained release of Zn2+ for at least 72 h. In diabetic rats models, ZnDBs/HBC composite hydrogel could accelerate the inflammatory process by regulating the expression of pro-inflammatory factor IL-6 and anti-inflammatory factor IL-10, and also promote tissue cell proliferation and collagen deposition, thereby restoring the normal healing process and accelerating wound healing. The wound contraction rate of the composite hydrogel group was more than 2 times that of the control group. Therefore, ZnDBs/HBC composite hydrogel has the potential to be used as a therapeutic dressing for diabetic chronic wounds.

Biomimetic Diatom Biosilica and Its Potential for Biomedical Applications and Prospects: A Review

Diatom biosilica is an important natural source of porous silica, with three-dimensional ordered and nanopatterned structures referred to as frustules. The unique features of diatom frustules, such as their high specific surface area, thermal stability, biocompatibility, and adaptable surface chemistry, render diatoms valuable materials for high value-added applications. These attributes make diatoms an exceptional cost-effective raw material for industrial use. The functionalization of diatom biosilica surface improves its biophysical properties and increases the potential applications. This review focuses on the potential uses of diatom biosilica including traditional approaches and recent progress in biomedical applications. Not only well-studied drug delivery systems but also promising uses on bone regeneration and wound healing are covered. Furthermore, considerable aspects and possible future directions for the use of diatom biosilica materials are proposed to develop biomedical applications and merit further exploration.

The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.

The hierarchical porous structures of diatom biosilica-based hemostat: From selective adsorption to rapid hemostasis

Here, we developed a Ca2+ modified diatom biosilica-based hemostat (DBp-Ca2+) with a full scale hierarchical porous structure (pore sizes range from micrometers to nanometers). The unique porous size in stepped arrangement of DBp-Ca2+give it selective adsorption capacity during coagulation process, resulted in rapid hemorrhage control. Based on in vitro and in vivo studies, it was confirmed that the primary micropores of DBp-Ca2+gave it high porosity to hold water (water absorption: 78.46 ± 1.12 %) and protein (protein absorption: 83.7 ± 1.33 mg/g). Its secondary mesopores to macropores could reduce of water diffusion length to accelerate blood exchange (complete within 300 ms). The tertiary stacking pores of DBp-Ca2+ could absorb platelets and erythrocytes to reduce more than 50 % of thrombosis time, and provided enough contact between Ca active site and coagulation factors for triggering clotting cascade reaction. This work not only developed a novel DBs based hemostat with efficient hemorrhage control, but also provided new insights to study procoagulant mechanism of inorganic hemostat with hierarchical porous structure from selective adsorption to rapid hemostasis.

Recent Progress in Diatom Biosilica: A Natural Nanoporous Silica Material as Sustained Release Carrier

A drug delivery system (DDS) is a useful technology that efficiently delivers a target drug to a patient's specific diseased tissue with minimal side effects. DDS is a convergence of several areas of study, comprising pharmacy, medicine, biotechnology, and chemistry fields. In the traditional pharmacological concept, developing drugs for disease treatment has been the primary research field of pharmacology. The significance of DDS in delivering drugs with optimal formulation to target areas to increase bioavailability and minimize side effects has been recently highlighted. In addition, since the burst release found in various DDS platforms can reduce drug delivery efficiency due to unpredictable drug loss, many recent DDS studies have focused on developing carriers with a sustained release. Among various drug carriers, mesoporous silica DDS (MS-DDS) is applied to various drug administration routes, based on its sustained releases, nanosized porous structures, and excellent solubility for poorly soluble drugs. However, the synthesized MS-DDS has caused complications such as toxicity in the body, long-term accumulation, and poor excretion ability owing to acid treatment-centered manufacturing methods. Therefore, biosilica obtained from diatoms, as a natural MS-DDS, has recently emerged as an alternative to synthesized MS-DDS. This natural silica carrier is an optimal DDS platform because culturing diatoms is easy, and the silica can be separated from diatoms using a simple treatment. In this review, we discuss the manufacturing methods and applications to various disease models based on the advantages of biosilica.

Enhancement of hemostatic properties of Cyclotella cryptica frustule through genetic manipulation

BACKGROUND

The silicified cell wall of diatoms, also known as frustule, shows huge potential as an outstanding bio-nanomaterial for hemostatic applications due to its high hemostatic efficiency, good biocompatibility, and ready availability. As the architectural features of the frustule determine its hemostatic performance, it is of great interest to develop an effective method to modify the frustule morphology into desired patterns to further improve hemostatic efficiency.

RESULTS

In this study, the gene encoding Silicalemma Associated Protein 2 (a silicalemma-spanning protein) of Cyclotella cryptica (CcSAP2) was identified as a key gene in frustule morphogenesis. Thus, it was overexpressed and knocked down, respectively. The frustule of the overexpress lines showed no obvious alteration in morphology compared to the wild type (WT), while the size, specific surface area (BET), pore volume, and pore diameter of the knockdown strains changed greatly. Particularly, the knockdown frustules achieved a more pronounced coagulation effect and in vivo hemostatic performance than the WT strains. Such observations suggested that silicalemma proteins are ideal genetic encoding targets for manipulating frustule morphology associated hemostatic properties. Furthermore, the Mantel test was adopted to identify the key morphologies associated with C. cryptica bleeding control. Finally, based on our results and recent advances, the mechanism of frustule morphogenesis was discussed.

CONCLUSION

This study explores a new strategy for enhancing the hemostatic efficiency of the frustule based on genetic morphology modification and may provide insights into a better understanding of the frustule morphogenesis mechanism.

Mussel-inspired nanoparticle composite hydrogels for hemostasis and wound healing

Uncontrolled hemorrhage caused by trauma can easily lead to death. Efficient and safe hemostatic materials are an urgent and increasing need for hemostatic research. Following a trauma, wound healing is induced by various cellular mechanisms and proteins. Hemostatic biomaterials that can not only halt bleeding quickly but also provide an environment to promote wound healing have been the focus of research in recent years. Mussel-inspired nanoparticle composite hydrogels have been propelling the development of hemostatic materials owing to their unique advantages in adhesion, hemostasis, and bacteriostasis. This review summarizes the hemostatic and antimicrobial fundamentals of polydopamine (PDA)-based nanomaterials and emphasizes current developments in hemorrhage-related PDA nanomaterials. Moreover, it briefly discusses safety concerns and clinical application problems with PDA hemostatic nanomaterials.

Copper-deposited diatom-biosilica enhanced osteogenic potential in periodontal ligament stem cells and rat cranium

This study aimed to establish that copper-deposited Diatom-biosilica have the potential and possibility for clinical applications in repairing bone defects in a state of inflammation, such as periodontitis. Treatment of alveolar bone defects caused by periodontitis is a major challenge for clinicians. To achieve better repair results, the material should not only be bone conductive but also have the ability to stimulate osteogenesis and angiogenesis at the lesion site. Copper (II) and silicon (IV) ions could react to form basic copper silicate, which promoted both osteogenesis and angiogenesis. The mineralized diatom (Cu-DBs) loaded with copper (II) ions were synthesized by processing diatom shells using a hydrothermal method. Periodontal ligament stem cells (PDLSCs) are used to detect the osteogenic properties of Cu-DBs at the gene and protein levels. Using a rat cranial defect model and a full-thickness skin incision model to test the osteogenic properties of Cu-DBs in vivo. Compared with untreated diatoms (DBs), Cu-DBs extract significantly promoted the expression of osteogenesis-related factors like ALP, RUNX2, BSP, OCN, and OPN in PDLSCs. In vivo experiments further confirmed that Cu-DBs could effectively stimulate the osteogenesis of a rat skull defect and promote angiogenesis, significantly inhibit the inflammatory responses to bone damages, and reduce the infiltration of inflammatory immune cells to the lesion site. Due to the unique chemical characteristics of Si⁴⁺ and Cu²⁺ ions, the Cu-DBs composite biomaterial could enhance the osteogenic differentiation of PDLSCS in vitro, as well as stimulate the osteogenesis of the rat in vivo.

PEG-mediated hybrid hemostatic gauze with in-situ growth and tightly-bound mesoporous silicon

Pre-hospital control of bleeding is critical to save lives, however the development of hemostatic agents with efficient and safe performance is still a challenge. In this study, a hybrid hemostatic gauze (MG-PEG) with in-situ growth and tightly bound mesoporous silicon (MSN) was prepared by template method for hemorrhage control. This material integrated meso-porosity, blood coagulation and stability into flexible gauze fiber. The PEG in MG-PEG was not only used as template for the in-suit MSN growth, but also acted as joint connection between the gauze fibers and MSN. The MSN particles were firmly bound to the surface of gauze fibers with extremely low leakage after 3 min of sonication and displayed a comparable coagulant activity to untreated sample. The results of animal experiments confirmed that MG-PEG possessed superior hemostatic performance over silicates-based inorganic hemostasis-Combat Gauze, in terms of higher coagulant activity (in vivo clotting time <200 s), minimized loss of active components (liquids OD was only 3 % of CG), well biocompatibility (hemolysis ratio < 5 %, no cytotoxicity) and wider indications range for practical application.

Diatomite hemostatic particles with hierarchical porous structure for rapid and effective hemostasis

The development of fast, safe and effective hemostatic materials is crucial for pre-hospital first aid. In this study, diatomite hemostatic granules (Dhp) were developed by rotating granulation method using silica sol as binder. During rotating granulation process, the Pre-Dhp were prepared by rolling snowball effect, in which nano-silica in silica sol uniformly distributed on the surface of diatomite and polymerized through hydrogen bond to produce strong adhesion. After high-temperature calcination, the hydrogen bond transformed to silica oxygen bond and the three-dimensional gel network formed by silica sol was destroyed to exposed the pores of diatomite. Dhp retained the porous structure of diatomite with hierarchical porous structure (from nano to micro scale). Dhp could quickly adsorb the tangible components in the blood, exhibited rapid hemostatic ability (clotting time was shortened by 43 % than that of control group), and good biocompatibility (hemolysis rate < 7 %, no cytotoxicity). Dhp residue was not found in the wound of rat tail amputation model, indicating that the adhesion of silica sol and high-temperature curing treatment enhanced the stability of Dhp and reduced the hidden danger of micro thrombosis caused by residual substances entering blood vessels. Our study proved that Dhp prepared by silica sol bonding and rotary granulation was excellent hemostatic material with non-toxic side effects and rapid coagulation promotion.

Reversible Regulation of the Reactive Oxygen Species Level Using a Semiconductor Heterojunction

Here, we proposed a novel solution for reversible regulation of the reactive oxygen species (ROS) level using a semiconductor heterojunction. Two metal-based ROS scavengers containing n-type CeO₂ nanoparticles and n-type Cu-doped diatom biosilica (Cu-DBs) were integrated by a hydrothermal method to form a typical n-n semiconductor heterojunction (Ce/Cu-DBs). Unlike the control of the ROS level by a single ROS scavenger or ROS-generating agent, Ce/Cu-DBs could quickly eliminate ROS by cascade catalytic reaction, which readily switched to ROS generation through a near-infrared (NIR)-triggered photocatalytic effect. This NIR mediated ROS regulation system provided a noninvasive strategy for reversible control of the ROS level in vitro and in vivo. The Ce/Cu-DBs could relieve cellular oxidative stress by clearing local excessive ROS while inhibiting bacterial growth by increasing ROS levels under NIR radiation. Benefiting from the reversible regulatory effect of Ce/Cu-DBs, programmable healing of infected wounds was realized via on-demand anti-infection and inflammation reduction. This work provided a general method with highly spatiotemporal resolution to a remote and sustainable control ROS level, which had great potential for the biomedical field and regulation of chemical reactions.

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.

Preparation of Chitosan/Clay Composites for Safe and Effective Hemorrhage Control

Uncontrolled hemorrhage from trauma or surgery can lead to death. In this study, chitosan/kaolin (CSK) and chitosan/montmorillonite (CSMMT) composites were prepared from chitosan (CS), kaolin (K), and montmorillonite (MMT) as raw materials to control bleeding. The physiochemical properties and surface morphology of CSK and CSMMT composites were analyzed by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potentials, and X-ray fluorescence (XRF). The hemostatic mechanism was measured in vitro by activated partial thromboplastin time (APTT), prothrombin time (PT), in vitro clotting time, erythrocyte aggregation, and thromboelastogram (TEG). The hemostasis ability was further verified by using tail amputation and arteriovenous injury models in rats. The biocompatibility of CSK and CSMMT was evaluated by in vitro hemolysis, cytotoxicity assays, as well as acute toxicity test and skin irritation tests. The results show that CSK and CSMMT are promising composite materials with excellent biocompatibility and hemostatic properties that can effectively control bleeding.

Copper deposited diatom-biosilica with enhanced photothermal and photodynamic performance for infected wound therapy

Considering the increase in drug resistance due to the abuse of antibiotics, the development of non-conventional antibiotics for the treatment of bacterial infections is necessary and urgent.

Study on the Hemostasis Characteristics of Biomaterial Frustules Obtained from Diatom Navicula australoshetlandica sp

Diatoms, known as photosynthetic unicellular algae, can produce natural biosilica frustules that exhibit great biocompatibility, superhydrophilicity, and superhemophilicity. In our study, the diatom Navicula australoshetlandica sp. was isolated from aquaculture wastewater and pretreated to obtain frustules so as to explore their hemostasis characteristics. A special “porous web” (6–8 nm) substructure in the ordered nanopores (165–350 nm) of boat-shaped diatom frustule was observed in Navicula australoshetlandica sp. using SEM and TEM analysis. Moreover, X-ray, N₂ adsorption–desorption isotherms, and BET analysis showed that the diatom frustule is a mesoporous material with a surface area of 401.45 m² g⁻¹ amorphous silica. FTIR analysis showed that Navicula australoshetlandica sp. frustules possessed abundant OH functional groups. A low hemolysis ratio was observed for 1–5 mg mL⁻¹ diatom frustules that did not exceed 1.55 ± 0.06%, which indicates favorable hemocompatibility. The diatom frustules exhibited the shortest clotting time (134.99 ± 7.00 s) with a hemostasis material/blood (mg/μL) ratio of 1:100, which is 1.83 times (112.32 s) shorter than that of chitosan. The activated partial thromboplastin time (aPTT) of diatom frustule was also 44.53 s shorter than the control. Our results demonstrate the potential of Navicula australoshetlandica sp. diatom frustules to be used as medical hemostasis material.