Blood clot initiation by mesocellular foams: dependence on nanopore size and enzyme immobilization

New insights in large-pores mesoporous silica microspheres for hemostatic application

Hemorrhages are still considered a common cause of death and despite the availability of different hemostatic agents it is still necessary to develop more effective hemostats for bleeding managements in emergency situations. Herein, large-pores mesoporous silica microspheres (MSM) were synthesized, and their surface was modified to enrich the hydroxyls population with the aim of achieving a material with enhanced water adsorption capacity and high hemostatic ability. The success of surface modification was investigated by Fourier Transform Infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA), which confirmed the increase in the amount of surface hydroxyl groups. A hemolysis assay as well as a clotting test were carried out to evaluate the hemocompatibility and hemostatic ability, respectively. It was found that the modified material presented the lowest hemolytic ratio and the lowest clotting time. The novelty of the paper is mainly due to the coupling of the hemostatic ability test with the adsorption microcalorimetry of water. In fact, being the water adsorption on the material surface a crucial factor in the hemostatic activity, microcalorimetry was used for the first time to study the adsorption of water and estimate its heat of adsorption. The data obtained showed that the modified MSM presents a surface able to adsorb a higher amount of water, compared to the pristine MSM, with a low molar heat of adsorption (about 35 kJ/mol), which renders the modified MSM presented in the present study an excellent candidate for producing novel hemostats.

Multi-functional dual-layer nanofibrous membrane for prevention of postoperative pancreatic leakage

Postoperative pancreatic leakage due to pancreatitis in patients is a life-threatening surgical complication. The majority of commercial barriers are unable to meet the demands for pancreatic leakage due to poor adhesiveness, toxicity, and inability to degrade. In this study, we fabricated mitomycin-c and thrombin-loaded multifunctional dual-layer nanofibrous membrane with a combination of alginate, PCL, and gelatin to resolve the leakage due to suture line disruption, promote hemostasis, wound healing, and prevent postoperative tissue adhesion. Electrospinning was used to fabricate the dual-layer system. The study results demonstrated that high gelatin and alginate content in the inner layer decreased the fiber diameter and water contact angle, and crosslinking allowed the membrane to be more hydrophilic, making it highly biodegradable, and adhering firmly to the tissue surfaces. The results of in vitro biocompatibility and hemostatic assay revealed that the dual-layer had a higher cell proliferation and showed effective hemostatic properties. Moreover, the in vivo studies and in silico molecular simulation indicated that the dual layer was covered at the wound site, prevented suture disruption and leakage, inhibited hemorrhage, and reduced postoperative tissue adhesion. Finally, the study results proved that dual-layer multifunctional nanofibrous membrane has a promising therapeutic potential in preventing postoperative pancreatic leakage.

Polydopamine-Coated Silk Fiber with Controllable Length for Enhanced Hemostatic Application

The development of highly effective hemostatic materials with high biocompatibility and outstanding performance is vital to the field of biomaterials. In this study, we develop a hemostatic fiber material that exhibits high biocompatibility and excellent performance. By incorporating polydopamine (PDA) into the alkaline treatment of silk fibroin (SF), we achieve PDA-coated SF fibers with lengths that can be controlled by the alkaline concentration. The PDA coating significantly enhances the hemostatic ability of the silk fibers and exhibits superior performance in both in vitro and ex vivo experiments. By performing animal studies involving a mouse liver puncture model and a femoral vein incision model, we demonstrate the remarkable hemostatic capability of the PDA-coated SF fibers, as evidenced by the lower blood loss compared to that of a commercial hemostat powder. These findings highlight the potential of applying a PDA-assisted alkaline treatment to SF fibers to efficiently create hemostatic fibers with controllable lengths, which would be promising candidates for clinical hemostatic applications.

Mesoporous Bioactive Glass-Graphene Oxide Composite Aerogel with Effective Hemostatic and Antibacterial Activities

Hemorrhage and infection after emergency trauma are two main factors that cause deaths. It is of great importance to instantly stop bleeding and proceed with antibacterial treatment for saving lives. However, there is still a huge need and challenge to develop materials with functions of both rapid hemostasis and effective antibacterial therapy. Herein, we propose the fabrication of a composite aerogel mainly consisting of mesoporous bioactive glass (MBG) and graphene oxide (GO) through freeze-drying. This composite aerogel has a three-dimensional porous structure, high absorption, good hydrophilicity, and negative zeta potential. Moreover, it exhibits satisfactory hemostatic activities including low BCI, good hemocompatibility, and activation of intrinsic pathways. When applied to rat liver injury bleeding, it can decrease 60% hemostasis time and 75% blood loss amount compared to medical gauze. On the other hand, the composite aerogel shows excellent photothermal antibacterial capacity against Staphylococcus aureus and Escherichia coli. Animal experiments further verify that this composite aerogel can effectively kill bacteria in wound sites via photothermal treatment and promote wound healing. Hence, this MBG-GO composite aerogel makes a great choice for the therapy of emergency trauma with massive hemorrhage and bacterial infection.

In vitro analysis of tantalum-containing mesoporous bioactive glass fibres for haemostasis

Haemorrhage is the leading cause of battlefield deaths and second most common cause for civilian mortality worldwide. Biomaterials-based haemostatic agents are used to aid in bleeding stoppage; mesoporous bioactive glasses (MBGs) are candidates for haemostasis. Previously made Tantalum-containing MBG (Ta-MBG) powders' compositions were fabricated as electrospun fibres for haemostatic applications in the present study. The fibres were fabricated to address the challenges associated with the powder form: difficult to compress without gauze, getting washed away in profuse bleeding, generating dust in the surgical environment, and forming thick callus-difficult to remove for surgeons and painful for patients. Ta-MBGs were based on (80-x)SiO2-15CaO-5P2O5-xTa2O5 mol% compositions with x = 0 (0Ta), 0.5 (0.5Ta), 1 (1Ta), and 5 (5Ta) mol%. The present study details the fibres' in vitro analyses, elucidating their cytotoxic effects, and haemostatic capabilities and relating these observations to fibre chemistry and previously fabricated powders of the same glasses. As expected, when Ta addition is increased at the expense of silica, a new FTIR peak (non-bridging oxygen-silicon, Si-NBO) develops and Si-O-Si peaks become wider. Compared to 0Ta and 1Ta fibres, 0.5Ta show Si-O peaks with reduced intensity. The fibres had a weaker intensity of Si-NBO peaks and release fewer ions than powders. A reduced ion profile provides fibres with a stable matrix for clot formation. The ion release profile for 1Ta and 5Ta fibres was significantly lower than 0Ta and 0.5Ta fibres. Ta-MBGs were not found to be cytotoxic to primary rat fibroblasts using a methyl thiazolyl tetrazolium (MTT) assay. Furthermore, a modified activated partial thromboplastin time assay analysing the fibrin absorbance showed that the absorption increases from physiological clotting < 0Ta < 0.5Ta < 5Ta < commercial haemostat, Surgical SNoWTM, Ethicon, USA < 1Ta. Higher absorption signifies a stronger clot. It is concluded that Ta-MBG fibres can provide stable matrix for clot formation and 1Ta can potentially enhance clotting best among other Ta-MBGs.

Porcine liver injury model to assess tantalum-containing bioactive glass powders for hemostasis

This study evaluates compositions of tantalum-containing mesoporous bioactive glass (Ta-MBG) powders using a porcine fatal liver injury model. The powders based on (80-x)SiO₂-15CaO-5P₂O₅-xTa₂O₅ compositions with x = 0 (0Ta/Ta-free), 1 (1Ta), and 5 (5Ta) mol% were made using a sol-gel process. A class IV hemorrhage condition was simulated on the animals; hemodynamic data and biochemical analysis confirmed the life-threatening condition. Ta-MBGs were able to stop the bleeding within 10 min of their application while the bleeds in the absence of any intervention or in the presence of a commercial agent, Arista^TM (Bard Davol Inc., Rhode Island, USA) continued for up to 45 min. Scanning electron microscopy (SEM) imaging of the blood clots showed that the presence of Ta-MBGs did not affect clot morphology. Rather, the connections seen between fibrin fibers of the blood clot and Ta-MBG powders point towards the powders' surfaces embracing fibrin. Histopathological analysis of the liver tissue showed 5Ta as the only composition reducing parenchymal hemorrhage and necrosis extent of the tissue after their application. Additionally, 5Ta was also able to form an adherent clot in worst-case scenario bleeding where no adherent clot was seen before the powder was applied. In vivo results from the present study agree with in vitro results of the previous study that 5Ta was the best Ta-MBG composition for hemostatic purposes. Graphical abstract.

Mesopore Controls the Responses of Blood Clot-Immune Complex via Modulating Fibrin Network

Formation of blood clots, particularly the fibrin network and fibrin network-mediated early inflammatory responses, plays a critical role in determining the eventual tissue repair or regeneration following an injury. Owing to the potential role of fibrin network in mediating clot-immune responses, it is of great importance to determine whether clot-immune responses can be regulated via modulating the parameters of fibrin network. Since the diameter of D-terminal of a fibrinogen molecule is 9 nm, four different pore sizes (2, 8, 14, and 20 nm) are rationally selected to design mesoporous silica to control the fibrinogen adsorption and modulate the subsequent fibrin formation process. The fiber becomes thinner and the contact area with macrophages decreases when the pore diameters of mesoporous silica are greater than 9 nm. Importantly, these thinner fibers grown in pores with diameters larger than 9 nm inhibit the M1-polorazation of macrophages and reduce the productions of pro-inflammatory cytokines and chemokines by macrophages. These thinner fibers reduce inflammation of macrophages through a potential signaling pathway of cell adhesion-cytoskeleton assembly-inflammatory responses. Thus, the successful regulation of the clot-immune responses via tuning of the mesoporous pore sizes indicates the feasibility of developing advanced clot-immune regulatory materials.

Influence of nanoparticles on the haemostatic balance: between thrombosis and haemorrhage

Maintenance of a delicate haemostatic balance or a balance between clotting and bleeding is critical to human health. Irrespective of administration route, nanoparticles can reach the bloodstream and might interrupt the haemostatic balance by interfering with one or more components of the coagulation, anticoagulation, and fibrinolytic systems, which potentially lead to thrombosis or haemorrhage. However, inadequate understanding of their effects on the haemostatic balance, along with the fact that most studies mainly focus on the functionality of nanoparticles while forgetting or leaving behind their risk to the body's haemostatic balance, is a major concern. Hence, our review aims to provide a comprehensive depiction of nanoparticle-haemostatic balance interactions, which has not yet been covered. The synergistic roles of cells and plasma factors participating in haemostatic balance are presented. Possible interactions and interference of each type of nanoparticle with the haemostatic balance are comprehensively discussed, particularly focusing on the underlying mechanisms. Interactions of nanoparticles with innate immunity potentially linked to haemostasis are mentioned. Various physicochemical characteristics that influence the nanoparticle-haemostatic balance are detailed. Challenges and future directions are also proposed. This insight would be valuable for the establishment of nanoparticles that can either avoid unintended interference with the haemostatic balance or purposely downregulate/upregulate its key components in a controlled manner.

Paraffin-Coated Hydrophobic Hemostatic Zeolite Gauze for Rapid Coagulation with Minimal Adhesion

To solve the problem of strong adhesion and excessive blood loss caused by the use of hydrophilic zeolite gauze (Z-Gauze) in uncontrollable bleeding, we have modified the surface of commercial Z-Gauze with a paraffin coating and prepared a hydrophobic dressing PZ-Gauze. After paraffin coating, the adhesion of Z-Gauze was reduced without an obvious decrease in coagulation activity. The clotting time of the hydrophobic PZ-Gauze was reduced from 378.3 to 154.6 s compared with that of cotton gauze, and the peeling force was decreased from 348.8 to 84.7 mN compared with that of Z-Gauze. Besides, PZ-Gauze can efficiently cut down the blood loss during treatment. On the basis of in vitro and in vivo experiments, it is confirmed that surface hydrophobic modification does not change the procoagulant performance because of the maintained cation exchange capacity of zeolites, and the reduced blood loss as well as enhanced difficulty for fibrin adhesion is attributed to its hydrophobicity. This is different from the traditional gauze procoagulant theories, where gauze hydrophilicity and procoagulant performance are always positively correlated.

Preparation and application of quick hemostatic gauze based on biomimetic mineralized thrombin

Thrombin is a serine protease known as activated coagulation factor II and is primarily applied as an effective local hemostatic agent. However, its clinical application is hindered by drawbacks, such as high sensitivity to the surrounding environment, instability and poor storage stability, easy inactivation, and low bioavailability. The biological functions of biomacromolecules in harsh environments can be preserved through biomineralization. Despite the success of biomimetic mineralization, limited consideration has been given to the mineral-based methods and the effect of various metal ions on enzyme activity. To explore an efficient technique for biomimetic mineralized thrombin, six kinds of ion/thrombin hybrid microflowers and two kinds of thrombin/MOF were synthesized in this work. The results showed that Zn-HNFs-G exhibits good hemostatic effect and maintains high enzymatic activity when exposed to high-temperature conditions. Meanwhile, Fe-HNFs-G, Thrombin@ZIF-8-G and Thrombin@MAF-7-G possess negligible enzyme protection.

Thrombin immobilized polydopamine-diatom biosilica for effective hemorrhage control

In this study, an efficient composite hemostatic material (DA-diatom-T) was prepared, using a polydopamine layer as a linker to immobilize thrombin on the surface of diatom biosilica. DA-diatom-T retained the porous structure of the diatom with high water absorption capacity, which can absorb 31 times its own weight of water. The thrombin activity of DA-diatom-T was as high as 5.81 U mg-1 that could be maintained at 67% after 30 days at room temperature. DA-diatom-T exhibited non-toxicity to mouse fibroblast cell lines, favorable hemocompatibility and fast procoagulant ability. DA-diatom-T could promote the initiation of the coagulation process and increase platelet activity and blood clot strength to form a physical barrier at the wound. In an in vivo study, DA-diatom-T could significantly reduce the clotting time and reduce the bleeding volume. The above results showed that DA-diatom-T had potential as a new hemostatic material.

Tentative identification of key factors determining the hemostatic efficiency of diatom frustule

It is increasingly essential to develop excellent materials for rapid hemorrhage control. Our previous study showed that centric diatoms such as frustules were superior to QuikClot® in hemostasis, however, related studies in pennate diatoms are still scarce. The morphological and physicochemical properties of pennate diatoms are quite different from those of centric diatoms, meaning that significant differences may also be observed from their hemostatic effects. Thus, the hemostasis effects of four pennate diatom frustules (Cocconeiopsis orthoneoides, Navicula avium, Navicula sp., and Pleurosigma indicum) were investigated in this study. Herein, all diatom frustules demonstrated outstanding hemostasis performance. For example, the in vitro coagulation time of C. orthoneoides (100.33 ± 9.5 s) was 32.4% lower than that of QuikClot®. Meanwhile, the hemostatic times of C. orthoneoides in the rat tail amputation and femoral artery models were 82 s and 180 s, respectively, only around one-half and one-third of the QuikClot® values. Moreover, the blood loss amounts of C. orthoneoides in the rat tail amputation and femoral artery model were 73.4% and 61% less than that of QuikClot®. Besides that, diatom frustules also exhibited favorable biocompatibility (hemolysis ratio <5%, MEFs cell viabilities >80%, and no inflammation). To find out the key factors underlying the hemostatic effect of frustules, Pearson correlation analysis was further performed in this study. The results demonstrated that the coagulation reaction time (R) was negatively correlated with the specific surface area and liquid absorbability but positively with the diatom pore diameter. The angle α, indicating the clot formation rate, was negative to the diatom size and pore diameter. Additionally, MA also showed a negative correlation with the BET value. This study can enrich our knowledge about the application potential of diatoms in the field of bleeding control and is helpful in deepening our understanding about the hemostatic mechanism of frustules.

Engineered nanomedicines for tumor vasculature blockade therapy

Tumor vasculature blockade therapy (TVBT), including angiogenesis inhibition, vascular disruption, and vascular infarction, provides a promising treatment modality for solid tumors. However, low selectivity, drug resistance, and possible severe side effects have limited the clinical transformation of TVBT. Engineered nanoparticles offer potential solutions, including prolonged circulation time, targeted transportation, and controlled release of TVBT agents. Moreover, engineered nanomedicines provide a promising combination platform of TVBT with chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, ultrasound therapy, and gene therapy. In this article, we offer a comprehensive summary of the current progress of engineered nanomedicines for TVBT and also discuss current deficiencies and future directions for TVBT development. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Recent Advances in Hemostasis at the Nanoscale

Rapid and effective hemostatic materials have received wide attention not only in the battlefield but also in hospitals and clinics. Traditional hemostasis relies on materials with little designability which has many limitations. Nanohemostasis has been proposed since the use of peptides in hemostasis. Nanomaterials exhibit excellent adhesion, versatility, and designability compared to traditional materials, laying a good foundation for future hemostatic materials. This review first summarizes current hemostatic methods and materials, and then introduces several cutting-edge designs and applications of nanohemostatic materials such as polypeptide assembly, electrospinning of cyanoacrylate, and nanochitosan. Particularly, their advantages and working mechanisms are introduced. Finally, the challenges and prospects of nanohemostasis are discussed.

Gold nanoparticles for the in situ polymerization of near-infrared responsive hydrogels based on fibrin

Non-invasiveness and relative safety of photothermal therapy, which enables local hyperthermia of target tissues using a near infrared (NIR) laser, has attracted increasing interest. Due to their biocompatibility, amenability of synthesis and functionalization, gold nanoparticles have been investigated as therapeutic photothermal agents. In this work, hollow gold nanoparticles (HGNP) were coated with poly-l-lysine through the use of COOH-Poly(ethylene glycol)-SH as a covalent linker. The functionalized HGNP, which peak their surface plasmon resonance at 800 nm, can bind thrombin. Thrombin-conjugated HGNP conduct in situ fibrin polymerization, facilitating the process of generating photothermal matrices. Interestingly, the metallic core of thrombin-loaded HGNP fragmentates at physiological temperature. During polymerization process, matrices prepared with thrombin-loaded HGNP were loaded with genetically-modified stem cells that harbour a heat-activated and ligand-dependent gene switch for regulating transgene expression. NIR laser irradiation of resulting cell constructs in the presence of ligand successfully triggered transgene expression in vitro and in vivo. STATEMENT OF SIGNIFICANCE: Current technological development allows synthesis of gold nanoparticles (GNP) in a wide range of shapes and sizes, consistently and at scale. GNP, stable and easily functionalized, show low cytotoxicity and high biocompatibility. Allied to that, GNP present optoelectronic properties that have been exploited in a range of biomedical applications. Following a layer-by-layer functionalization approach, we prepared hollow GNP coated with a positively charged copolymer that enabled thrombin conjugation. The resulting nanomaterial efficiently catalyzed the formation of fibrin hydrogels which convert energy of the near infrared (NIR) into heat. The resulting NIR-responsive hydrogels can function as scaffolding for cells capable of controlled gene expression triggered by optical hyperthermia, thus allowing the deployment of therapeutic gene products in desired spatiotemporal frameworks.

A tightly-bonded and flexible mesoporous zeolite-cotton hybrid hemostat

Achieving rapid definitive hemostasis is essential to ensure survival of patients with massive bleeding in pre-hospital care. It is however challenging to develop hemostatic agents or dressings that simultaneously deliver a fast, long-lasting and safe treatment of hemorrhage. Here, we integrate meso-/micro-porosity, blood coagulation and stability into a flexible zeolite-cotton hybrid hemostat. We employ an on-site template-free growth route that tightly binds mesoporous single-crystal chabazite zeolite onto the surface of cotton fibers. This hemostatic material maintains high procoagulant activity after water flow treatment. Chabazite particles are firmly anchored onto the cotton surface with < 1% leaching after 10 min of sonication. The as-synthesized hemostatic device has superior hemostatic performance over most other clay or zeolite-based inorganic hemostats, in terms of higher procoagulant activity, minimized loss of active components and better scalability for practical applications (a hemostatic T-shirt is hereby demonstrated as an example).

Zeolites have attracted attention and have been applied as haemostatic agents; however, there are issues associated with released zeolite powder. Here, the authors report on the growth of zeolites on cotton fibres with high stability and haemostatic ability.

Well-ordered mesoporous silica and bioactive glasses: promise for improved hemostasis

Mesoporous silica and bioactive glasses with unique textural properties are new generations of inorganic hemostats with efficient hemostatic ability.

Enhancement of hemostatic property of plant derived oxidized nanocellulose-silk fibroin based scaffolds by thrombin loading

To combat post-surgical and traumatic bleeding conditions effective hemostasis is of great importance. The study was designed to investigate the effect of thrombin (Th) loading on hemostatic performance of TEMPO-oxidized cellulose nanofiber (TOCN)-silk fibroin (SF) scaffolds. Addition of SF with TOCN significantly (***P < 0.001) increased blood absorption capacity and improved biocompatibility of TOCN. Thrombin loading potentiated platelet activation and hemostatic property of scaffolds (TOCN-SF-Th) compared to samples without thrombin (TOCN-SF). The hemostatic time of TOCN-SF5-Th in rabbit ear artery bleeding model was reduced (*** P < 0.001) to 114 s from 220 s of TOCN-SF5. Reduction in bleeding time and blood loss of TOCN-SF5-Th in rat tail amputation and liver avulsion model was comparable to commercial hemostat (Floseal). Surface morphology (SEM) of samples applied on bleeding site showed that RBCs and fibrin fiber could strongly interact with TOCN-SF and TOCN-SF-Th scaffolds. The result suggests that TOCN-SF-Th can be a promising candidate for designing hemostatic agents.

Chitosan-Based Composite Materials for Prospective Hemostatic Applications

Effective hemostasis is vital to reduce the pain and mortality of patients, and the research and development of hemostatic materials are prerequisite for effective hemostasis. Chitosan (CS), with good biodegradability, biocompatibility and non-toxicity, has been widely applied in bio-medicine, the chemical industry, the food industry and cosmetics. The excellent hemostatic properties of CS have been extensively studied. As a result, chitosan-based composite hemostatic materials have been emerging. In this review, the hemostatic mechanism of chitosan is briefly discussed, and then the progress of research on chitosan-based composite hemostatic materials with multiple forms such as films, sponges, hydrogels, particles and fibers are introduced. Finally, future perspectives of chitosan-based composite hemostatic materials are given. The objective of this review is to provide a reference for further research and development of effective hemostatic materials.

Biosynthetic calcium-doped biosilica with multiple hemostatic properties for hemorrhage control

A sustainable and environmentally friendly biomineralization strategy was developed to obtain calcium-doped biosilica with excellent hemostatic properties and biocompatibility.

The effects of nanomaterials on blood coagulation in hemostasis and thrombosis

The blood coagulation balance in the organism is achieved by the interaction of the blood platelets (PLTs) with the plasma coagulation system (PCS) and the vascular endothelial cells. In healthy organism, these systems prevent thrombosis and, in events of vascular damage, enable blood clotting to stop bleeding. The dysregulation of hemostasis may cause serious thrombotic and/or hemorrhagic pathologies. Numerous engineered nanomaterials are being investigated for biomedical purposes and are unavoidably exposed to the blood. Also, nanomaterials may access vascular system after occupational, environmental, or other types of exposure. Thus, it is essential to evaluate the effects of engineered nanomaterials on hemostasis. This review focuses on investigations of nanomaterial interactions with the blood components involved in blood coagulation: the PCS and PLTs. Particular emphases include the pathophysiology of effects of nanomaterials on the PCS, including the kallikrein-kinin system, and on PLTs. Methods for investigating these interactions are briefly described, and a review of the most important studies on the interactions of nanomaterials with plasma coagulation and platelets is provided. WIREs Nanomed Nanobiotechnol 2017, 9:e1448. doi: 10.1002/wnan.1448 For further resources related to this article, please visit the WIREs website.

Chitosan-Coated Diatom Silica as Hemostatic Agent for Hemorrhage Control

Uncontrolled hemorrhage leads to high death risk both in military and civilian trauma. Current hemostatic agents still have various limitations and side effects. In this study, natural diatom silica obtained from diatomite and diatom culture was purified and developed for hemorrhage control. To improve the biocompatibility and hemostatic performance of diatom silica, a series of chitosan-coated diatom (CS-diatom) was developed. The composition of CS-diatom prepared was optimized by in vitro hemocompatibility and blood coagulation evaluation for that prepared with 0.5%, 1%, 3%, and 5% chitosan. The results demonstrated that the CS-diatom prepared with 1% chitosan exhibited favorable biocompatibility (hemolysis ratio < 5%, no cytotoxicity to MEFs), great fluid absorbility (24.39 ± 1.53 times the weight of liquid), and desirable hemostasis effect (351 ± 14.73 s at 5 mg/mL, 248 ± 32.42s at 10 mg/mL). Further blood coagulation mechanism study indicated that CS-diatom could provide an ideal interface to induce erythrocyte absorption and aggregation, along with activating the intrinsic coagulation pathway and thus accelerated blood coagulation. Benefitting from the multiple hemostatic performances, CS-diatom showed the shortest clotting time (98.34 ± 26.54 s) and lowest blood loss (0.31 ± 0.11 g) in rat-tail amputation model compare to diatomite and diatom as well as gauze and commercial QuikClot zeolite. The results evidenced that the CS-diatom was a safe and effective hemostatic agent and provided a new understanding of nonsynthetic mesoporous materials for hemorrhage control.

Printable enzyme-embedded materials for methane to methanol conversion

An industrial process for the selective activation of methane under mild conditions would be highly valuable for controlling emissions to the environment and for utilizing vast new sources of natural gas. The only selective catalysts for methane activation and conversion to methanol under mild conditions are methane monooxygenases (MMOs) found in methanotrophic bacteria; however, these enzymes are not amenable to standard enzyme immobilization approaches. Using particulate methane monooxygenase (pMMO), we create a biocatalytic polymer material that converts methane to methanol. We demonstrate embedding the material within a silicone lattice to create mechanically robust, gas-permeable membranes, and direct printing of micron-scale structures with controlled geometry. Remarkably, the enzymes retain up to 100% activity in the polymer construct. The printed enzyme-embedded polymer motif is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas–liquid reactions.

There is a need for small-scale reactors that convert methane emissions to more valuable products to reduce climate impacts. Here, the authors show that printing 3D structures of the pMMO enzyme enables continuous methane conversion under ambient conditions and reduces mass transfer limitations.

Titanium implants coated with UV-irradiated vitamin D precursor and vitamin E: in vivo performance and coating stability

OBJECTIVES

This study aimed at evaluating the biological response of titanium implants coated with UV-irradiated 7-dehydrocholesterol (7-DHC) and vitamin E (VitE) in vivo and analyzing the effects of aging on their stability and bioactivity in vitro.

MATERIAL AND METHODS

Titanium surfaces were coated with 7-DHC and VitE, UV-irradiated and incubated for 48 h at 23°C to allow cholecalciferol synthesis. The in vivo biological response was tested using a rabbit tibia model after 8 weeks of healing by analyzing the wound fluid and the mRNA levels of several markers at the bone-implant interface (N = 8). The stability of the coating after storage up to 12 weeks was determined using HPLC analysis, and the bioactivity of the stored modified implants was studied by an in vitro study with MC3T3-E1 cells (N = 6).

RESULTS

A significant increase in gene expression levels of osteocalcin was found in the bone tissue attached to implants coated with the low dose of 7-DHC and VitE, together with a higher ALP activity in the wound fluid. Implants treated with the high dose of 7-DHC and VitE showed increased tissue necrosis and inflammation. Regarding the aging effects, coated implants were stable and bioactive up to 12 weeks when stored at 4°C and avoiding oxygen, light and moisture.

CONCLUSION

This study demonstrates that Ti implants coated with UV-irradiated 7-DHC and VitE promote in vivo gene expression of bone formation markers and ALP activity, while they keep their osteopromotive potential in vitro and composition when stored up to 12 weeks at 4°C.

Study of mesoporous magnesium carbonate in contact with whole human blood

The novel mesoporous magnesium carbonate Upsalite showed anticoagulant properties when incubated with whole blood, an effect most probably due to Ca²⁺uptake.

An enzyme-responsive controlled release system based on a dual-functional peptide

A new controlled release system was developed by loading a dual-functional peptide on a mesoporous silica material.

Blood clot initiation by mesoporous silica nanoparticles: dependence on pore size or particle size?

The hemostatic efficiency of mesoporous silica nanoparticles depends on pore size more than particle size, and biocompatibility is more related to particle size.

Hemostatic strategies for traumatic and surgical bleeding

Wide interest in new hemostatic approaches has stemmed from unmet needs in the hospital and on the battlefield. Many current commercial hemostatic agents fail to fulfill the design requirements of safety, efficacy, cost, and storage. Academic focus has led to the improvement of existing strategies as well as new developments. This review will identify and discuss the three major classes of hemostatic approaches: biologically derived materials, synthetically derived materials, and intravenously administered hemostatic agents. The general class is first discussed, then specific approaches discussed in detail, including the hemostatic mechanisms and the advancement of the method. As hemostatic strategies evolve and synthetic-biologic interactions are more fully understood, current clinical methodologies will be replaced.

Formation of aragonitic layered structures from kaolinite and amorphous calcium carbonate precursors

Clay materials have been an ever-present accoutrement of modern civilization; improvements to process these materials have quickened their utilization for use in complex multiaxial load-bearing structures. Specifically, with better methods to organize the constituent metal oxide components in clay, the distribution of characteristic nematic and smectic phases can be controlled. In this work, we utilize the interactions of an amorphous calcium carbonate phase with kaolinite to form a complex composite that can be organized into distinct hierarchical structures. We demonstrate that these ACC-kaolinite composites can maintain characteristic long-range-ordered layer-by-layer structures across many length scales, from nano- to millimeter, through convenient and economical processing at room temperature.

Toxicity of aluminum silicates used in hemostatic dressings toward human umbilical veins endothelial cells, HeLa cells, and RAW267.4 mouse macrophages

BACKGROUND

Aluminum silicates have been used to control bleeding after severe traumatic injury. QuikClot (QC) was the first such product, and WoundStat (WS) is the most recent. We recently observed that WS caused vascular thrombosis when applied to stop bleeding. This study investigated the cellular toxicity of WS in different cell types that may be exposed to this mineral and compared the results with other minerals such as bentonite, kaolin, and QuikClot ACS+ (QC+).

METHODS

Human umbilical vein endothelial cells (HUVEC), HeLa cells, and RAW267.4 mouse macrophage-like cells (RAW) were incubated directly with different concentrations of each mineral for 24 hours. Cell viability was determined metabolically using the AlamarBlue fluorescent technique. In another experiment, minerals were exposed to HUVEC via Transwell inserts with a polycarbonate filter (0.4-μm pore size) to prevent direct contact between cells and minerals for determining whether direct exposure or leaching compounds from minerals cause cytotoxicity.

RESULTS

Incubation of HUVEC and RAW cells with 1 to 100 μg/mL of the minerals for 24 hours resulted in differential toxicities. The cytotoxicity of WS was equal to that of bentonite and higher than kaolin and QC+. Neither cell type survived for 24 hours in the presence of 100 μg/mL WS or bentonite. These minerals, however, had little effect on the viability of HeLa cells. In the second HUVEC experiment, a 10 times higher concentration of these compounds placed in Transwell inserts yielded no decrease in cell viability. This result indicates that leaching toxicants or binding of nutrients by the ion-exchange properties of minerals did not cause the toxicity.

CONCLUSIONS

Although aluminum silicates seem relatively innocuous to epithelial cells, all produced some toxicity toward endothelial cells and macrophages. WS and bentonite were significantly more toxic than kaolin and zeolite present in QC+, respectively, at equivalent doses. The cytotoxic effect seemed to be caused by the direct contact of the minerals with the cells present in wounds. These data suggest that the future clearance of mineral-based hemostatic agents should require more extensive cytotoxicity testing than the current Food and Drug Administration requirements.

In mesopore protein digestion: a new forthcoming strategy in proteomics

The conventional protocols for in solution or in gel protein digestion require many steps and long reaction times. The use of trypsin immobilized onto solid supports has recently captured the attention of many research groups, because these systems can speed-up protein digestion significantly. The utilization of new materials such as mesoporous silica as supports, in which enzyme and substrate are dramatically concentrated and confined in the nanospace, offers new opportunities to reduce the complexity of proteomics workflows. An overview of the procedures for in situ proteolysis of single proteins or complex protein mixtures is reported, with a special focus on porous materials used as catalysts. The challenging efforts for designing such systems aimed at mimicking the biochemistry of living cells are reviewed. Potentials, limitations and challenges of this branch of enzyme catalysis, which we indicate as in mesopore digestion, are discussed, in relation to its suitability for high-speed and high-throughput proteomics.

Controlled electro-implementation of fluoride in titanium implant surfaces enhances cortical bone formation and mineralization

Previous studies have shown that bone-to-implant attachment of titanium implants to cortical bone is improved when the surface is modified with hydrofluoric acid. The aim of this study was to investigate if biological factors are involved in the improved retention of these implants. Fluoride was implemented in implant surfaces by cathodic reduction with increasing concentrations of HF in the electrolyte. The modified implants were placed in the cortical bone in the tibias of New Zealand white rabbits. After 4 weeks of healing, wound fluid collected from the implant site showed lower lactate dehydrogenase activity and less bleeding in fluoride-modified implants compared to control. A significant increase in gene expression levels of osteocalcin and tartrate-resistant acid phosphatase (TRAP) was found in the cortical bone attached to Ti implants modified with 0.001 and 0.01 vol.% HF, while Ti implants modified with 0.1% HF showed only induced TRAP mRNA levels. These results were supported by the performed micro-CT analyses. The volumetric bone mineral density of the cortical bone hosting Ti implants modified with 0.001% and 0.01% HF was higher both in the newly woven bone (<100 microm from the interface) and in the older Haversian bone (>100 microm). In conclusion, the modulation of these biological factors by surface modification of titanium implants with low concentrations of HF using cathodic reduction may explain their improved osseointegration properties.

Nanotechnology, nanotoxicology, and neuroscience

Nanotechnology, which deals with features as small as a 1 billionth of a meter, began to enter into mainstream physical sciences and engineering some 20 years ago. Recent applications of nanoscience include the use of nanoscale materials in electronics, catalysis, and biomedical research. Among these applications, strong interest has been shown to biological processes such as blood coagulation control and multimodal bioimaging, which has brought about a new and exciting research field called nanobiotechnology. Biotechnology, which itself also dates back approximately 30 years, involves the manipulation of macroscopic biological systems such as cells and mice in order to understand why and how molecular level mechanisms affect specific biological functions, e.g., the role of APP (amyloid precursor protein) in Alzheimer's disease (AD). This review aims (1) to introduce key concepts and materials from nanotechnology to a non-physical sciences community; (2) to introduce several state-of-the-art examples of current nanotechnology that were either constructed for use in biological systems or that can, in time, be utilized for biomedical research; (3) to provide recent excerpts in nanotoxicology and multifunctional nanoparticle systems (MFNPSs); and (4) to propose areas in neuroscience that may benefit from research at the interface of neurobiologically important systems and nanostructured materials.