Sponge for wounds
The RCTU has developed an effective hemostatic material from natural components
Blog of D.I. Mendeleev Russian State Technical University, Naked Science
Blood loss due to severe bleeding remains a common cause of death. Today there are a large number of hemostatic materials, but each of them has its own disadvantages – for example, poor biocompatibility or low sorption capacity. Chemists from the Mendeleev Russian Technical Technical University synthesized a new material based on chitosan and alginate biopolymers isolated from algae and crustacean shells, as well as silver nanoparticles. The material can not only effectively stop bleeding, but also has pronounced antibacterial activity.
The article is published in the International Journal of Polymeric Materials and Polymeric Biomaterials (Gordienko et al., The alginate–chitosan composite sponges with biogenic Ag nanoparticles produced by combining of cryostructure, ionotropic gelation and ion replacement methods).
Bleeding still remains a serious medical hazard and causes more than 30 percent of deaths from wounds. To stop the bleeding, you need a hemostatic material that can be easily fixed to the wound and, on the one hand, isolate it to speed up healing, and on the other hand, to ensure the removal of fluids and protection from infection.
There are many different hemostatic materials, but most of them focus only on stopping bleeding quickly, and are poorly suited for longer-term treatment. Russian scientists have proposed a new material consisting of three components: alginate and chitosan – biopolymers isolated from algae and crustacean shells, as well as silver nanoparticles. At the same time, the latter were obtained not by a standard chemical method, but by biological synthesis: nanosilver granules were produced by mushrooms that were grown in an environment rich in silver ions.
"On the basis of alginate, hydrogels are created – sponges insoluble in water, capable of collecting and giving away large volumes of liquid," says the first author of the work, associate professor of the D. I. Mendeleev Russian Technical University, Maria Gordienko. – But in order for these sponges not to dissolve in water, their structure needs to be stitched using crosslinking agents, which most often act as various toxic chemicals, and we replaced them with chitosan. It forms bonds with alginate, which leads to the formation of a gel that retains its stability even when immersed in a solution.
In addition, chitosan has an antibacterial effect, promotes the binding of blood components and wound healing. Finally, silver nanoparticles give the gel an additional antibacterial effect – so, in total, we have obtained a new hemostatic material with high biocompatibility and well-pronounced antibacterial properties. At the same time, its production technology ensures the preservation of a branched macroporous structure and, as a result, a high sorption capacity."
The synthesized gels look like a porous sponge up to 5 millimeters thick. They can be applied to open wounds to quickly stop bleeding and at the same time protect against infection. At the same time, the sponge is able to absorb large volumes of fluids released from wounds, while maintaining its mechanical stability. Then, if necessary – for example, if a surgeon needs to perform an operation and sew up a wound – the sponge can be easily removed.
Everything from nature: advantages and prospects of the new material
The main innovation of Russian researchers is a multi–stage synthesis process, which has not been used for hemostatic materials before. First, they obtained a soluble alginate hydrogel with silver nanoparticles, then cryostructured it – that is, cooled the material to -20 degrees, as a result of which a primary channel system was formed inside the sponge. Next, the material was brought into contact with a chitosan solution and, with gradual thawing at -5 degrees, chitosan molecules were bound to alginate and so the system was already sewn into an insoluble mesh sponge. Then the mixture was frozen again to -20 degrees and dried by sublimation to obtain the final material.
In a series of experiments, scientists evaluated the prospects of a new material for stopping bleeding. It turned out that its porosity is up to 50 percent, that is, the total volume of all pores accounts for half of the total volume of the gel, due to which it effectively absorbs liquids. At the same time, alginate-chitosan gels remain insoluble and mechanically stable at pH and temperature values characteristic of wounds, so it is suitable for these conditions. Finally, the antibacterial properties of the gels were studied separately. They were placed in Petri dishes, with three typical cultures of pathogens (Staphylococcus aureus Staphylococcus aureus, Pseudomonas aeruginosa Pseudomonas Pseudomonas aeruginosa and wax bacillus Bacillus cereus).
After 24 hours of the gels being in the bacterial environment, the scientists evaluated the size and shape of the free zones around the samples: the larger the size of the zone, the stronger the antibacterial effect. It turned out that alginate-chitosan sponges with silver nanoparticles have pronounced antibacterial properties, while sponges without the addition of silver do not have them. Scientists have not yet conducted experiments on real wounds, for which laboratory animals are needed. However, according to the totality of other data, it is already possible to talk about the prospects of a new material for stopping bleeding.
"The range of materials used for wound treatment is very large," says Gordienko. "And the main differences of our material are its really high sorption capacity and a biocompatible method of obtaining without chemical crosslinking agents – natural alginate, natural chitosan and nanoparticles of microbiological silver."
In August, the researchers received a positive decision to grant a patent for the material and the method of obtaining it, and are currently conducting an economic assessment of its prospects, developing laboratory regulations for the synthesis of a new material. In the future, they plan not only to conduct experiments on animals, but also to modify the gels so that pores of various sizes appear in them and the material can be used for the task of dividing blood into fractions.
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