Sodium carboxymethyl cellulose/sericin/calcium bentonite rapid hemostatic sponge fabricated by ambient pressure drying with excellent hemostatic performance and biocompatibility.

A natural polymer-based porous sponge with capillary-mimicking microchannels for rapid hemostasis

Currently, the need for research in the field of hemostatic materials seems to be a necessity. The purpose of this study was to prepare and assess a hemostatic polyurethane (PU) sponge containing kaolin (K), tannic acid (TA), and tranexamic acid (TXA) as effective, safe, and inexpensive hemostatic agents. K was incorporated into the sponge (at 4 or 8 wt%, named K4 or K8), also TA (at 1% or 3%, named TA1 or TA3) and TXA (at 300 mg/mL) were added. Four sponges, K4TA1, K4TA3, K8TA1, and K8TA3 were produced and compared via 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay, fluid uptake, drug release, and blood clotting time/index. K4TA3 was considered optimum and other experiments were continued with this sponge. Scanning electron microscopy results supported that the sponge had a porous structure, and Fourier transform infrared confirmed the corresponding PU spectra and the presence of hemostatic compounds. The hemostatic sponge exhibited a quick initial release of TA and TXA. K4TA3 sponge also exhibited appropriate water uptake. Besides, PU sponges illustrated no cytotoxicity towards human dermal fibroblasts. Furthermore, the sponge presented an antibacterial activity. Hemostatic capability was established in a rat‐tail amputation model bleeding in terms of blood loss and hemostasis time. We also validated the biocompatibility and safety of the materials by hemolysis assessment. This work demonstrated a simple and efficient PU hemostatic sponge that acts via more than one clotting mechanism to control bleeding.

A facile preparation of transparent methyltriethoxysilane based silica xerogel monoliths at ambient pressure drying

Freeze-casting has been wildly exploited to construct porous ceramics but usually requires costly and demanding freeze-drying (high vacuum, size limit, and supercooled chamber), which can be avoided by the ambient pressure drying (APD) technique. However, applying APD to freeze-cast ceramic based on an aqueous suspension is still challenging due to inert surface chemistry. Herein, a modified APD strategy is developed to improve the drying process of freeze-cast ceramics by exploiting the simultaneous ice etching, ionic cross-linking, and solvent exchange under mild conditions (-10-0 °C, ambient pressure). This versatile strategy is applicable to various ceramic species, metal ions, and freezing techniques. The incorporated metal ions not only enhance liquid-phase sintering, producing ceramics with higher density and mechanical properties than freeze-cast counterparts, but also render customizable coloration and antibacterial property. The cost-/time-efficient APD is promising for mass production and even successive production of large-size freeze-cast ceramics that exceed the size of commercial freeze-dryers.

The effect of iron acetylacetonate on the physico-chemical properties of waterglass based silica aerogels by ambient pressure drying has been investigated. Doping the gels with iron acetylacetonat (FeAA) facilitates in the diminution of the density of the aerogels. The well established silica network provides effective confinement of FeAA nanoparticles which resists the collapse of silica network during ambient pressure drying. Therefore, in the present paper, the effects of FeAA on the physico-chemical properties of the aerogels have been studied by varying the FeAA:Na2SiO3 molar ratio from 3 × 10−4 to 6 × 10−4. The aerogels were prepared via ambient pressure drying and characterized by the bulk density, thermal conductivity and water contact angle. The aerogel’s surface morphology, elemental analysis and pore structure were characterized by means of EDAX and FTIR, TEM and N2 adsorption- desorption analyzer. The high temperature hydrophobicity of these aerogels was checked by heating them in temperature controlled furnace. Silica aerogels with low density ~0.050 g/cc have been obtained using the molar ratio of Na2SiO3:H2O:FeAA:Citric acid:TMCS at 1:146.67:3 × 10−4:0.54:9.46, respectively. EDAX and FTIR studies show that the iron species are entrapped in the mesoporous framework and not took part in the bonding with silica.

Hydrophobic and elastic aerogels derived from methyltrimethoxysilane (MTMS) precursor were prepared by ambient pressure drying under various processing conditions, and their morphology and physical and mechanical properties were characterised and evaluated. The results of this study demonstrated that for inherently hydrophobic gels like MTMS based gels, high temperature ageing is a practical and effective means to reduce volume shrinkage and produce low bulk density monolithic aerogels at ambient pressure, without the need of any solvent exchange and surface modification. By using this simple method, we were able to produce an aerogel with a bulk density as low as 0.064g/cm3. The results also revealed a significant difference from that previously reported in the literature.

Effect of aging on silica aerogel properties

A quaternized chitosan and carboxylated cellulose nanofiber-based sponge with a microchannel structure for rapid hemostasis and wound healing

Peptide-immobilized starch/PEG sponge with rapid shape recovery and dual-function for both uncontrolled and noncompressible hemorrhage

Using ammonium bicarbonate (AB) particles as a porogen, chitosan (CS)-based hemostatic porous sponges were prepared in supercritical carbon dioxide due to its low viscosity, small surface tension, and good compatibility with organic solvent. Fourier transform infrared spectroscopy (FTIR) spectra demonstrated that the chemical compositions of CS and poly-(methyl vinyl ether-co-maleic anhydride) (PVM/MA) were not altered during the phase inversion process. The morphology and structure of the sponge after the supercritical fluid (SCF) process were observed by scanning electron microscopy (SEM). The resulting hemostatic sponges showed a relatively high porosity (about 80%) with a controllable pore size ranging from 0.1 to 200 μm. The concentration of PVM/MA had no significant influence on the porosity of the sponges. Comparative experiments on biological assessment and hemostatic effect between the resulting sponges and Avitene® were also carried out. With the incorporation of PVM/MA into the CS-based sponges, the water absorption rate of the sponges increased significantly, and the CS-PVM/MA sponges showed a similar water absorption rate (about 90%) to that of Avitene®. The results of the whole blood clotting experiment and animal experiment also demonstrated that the clotting ability of the CS-PVM/MA sponges was similar to that of Avitene®. All these results elementarily verified that the sponges prepared in this study were suitable for hemostasis and demonstrated the feasibility of using SCF-assisted phase inversion technology to produce hemostatic porous sponges.

Background: One of the important unsolved problems of hepatobiliary surgery is to stop the bleeding of the parenchymal organ. The most promising means of local hemostasis are spongy implants made of various materials, the study of which is one of the leading directions in modern surgery. Nevertheless, despite the relevance of the research, there is no uniform classification of the structural features of such hemostatics. Aims: to study the features of the surface of the application of hemostatic implants based on collagen and Carboxymethylcellulose Sodium. Materials and methods: the authors performed light microscopy of the samples, photographing and subsequent processing of the photographs obtained using the trial version of the graphic editor Adobe Photoshop CS6 (Adobe Systems, San Jose, United States of America) to obtain black and white images by enhancing the contrast (+400 ), which excluded the possibility of false color definition. The black and white pixels were counted using the Altami Studio 3.4 program (Altami LLC, St. Petersburg, Russian Federation). Then, the real pixel size was converted into percentages using the trial version of Statistica 10.0 (Dell Software Company, Round Rock, United States of America). After that, the ratio of low areas of the implant (black pixels) to high (white pixels) was determined.
 Results: According to the data obtained, a classification was developed for the heterogeneity of the surface of the relief of hemostatic implants, according to which all of them can be divided into three groups: with weak, moderate and strong severity of the heterogeneity of the surface relief. Conclusions: when correlating the obtained results and selected groups, it was found out that the hemostatic sponge Tachocomb (Takeda Pharmaceuticals LLC, Linz, Austria) has a slightly pronounced heterogeneity of the surface relief, and the hemostatic collagen sponge (OJSC Luga Belkozin, Luga, Russian Federation) and a Carboxymethylcellulose based hemostatic sponge (developed in cooperation with Linteks LLC, St. Petersburg, Russian Federation) - moderately pronounced surface heterogeneity.

4-Hydroxybenzenesulfonic acid triggers rapid preparation of phenolic aerogel composites by ambient pressure drying

Preparation of monolithic amorphous silica aerogel through promising valorization of silicomanganese slag

Dialdehyde starch cross-linked aminated gelatin sponges with excellent hemostatic performance and biocompatibility

Silica aerogel can be produced by using ambient pressure drying (APD) or supercritical drying depending on the required properties and kind of application. Processing time for ambient pressure dried silica aerogels are longer due to the time consuming steps such as hydrolysis and solvent exchange. Considerable decrease in time has been reported by a few research groups by employing shaking during the solvent exchange. We are reporting further reduction in processing time of tetraethoxysilane (TEOS)-based silica aerogel by carrying out the hydrolysis process at elevated temperature. The aerogel obtained in least processing time showed low density (0.066 kg/m3), low thermal conductivity (0.043 W/mK), high specific surface area, and porosity. This shows that elevated temperature hydrolysis does not hamper the desired properties of the product.