Study On Preparation And Performance Of Natural Polymer-based Fuctional Composite For Hemostatic Wound Dressing

In recent years, natural polymer hemostatic materials are attracting more and more researchers’ attention. In this paper, natural polymers, such as cellulose and collagen, were used to prepare a series of compound hemostatic materials with good hemostatic effect. The novel physical form of the oxidized regenerated cellulose membrane materials is of great significance to study hemostatic mechanism. Oxidized regenerated cellulose/collagen composite hemostatic sponge has excellent hemostatic effect and good antibacterial property. Poly(e-caprolactone) /collagen hemostatic repaired electrospun membrane has opened a new style of hemostatic materials with multi-functions, such as long-acting antibacterial, tissue repair and biodegradation.Although hemostatic effects of oxidized regenerated cellulose(ORC) are wellknown, its hemostatic mechanism has never been demonstrated clearly. Since thrombus formation is a kind of surface phenomenon, we changed the morphology of cellulose to form a membrane using ionic liquid as solution, and we also prepared ORC films using nitrogen dioxide(NO2)/carbon tetrachloride(CCl4) oxidation system reacting for 16, 40, 64 and 88 h, respectively. FT-IR and NMR spectra showed that NO2/CCl4 oxidation system had a high selectivity on hydroxyl group at C6 of regenerated cellulose. As the oxidation time prolonging, the carboxyl content was enhanced and the DP was reduced. The XPS results suggested that new carboxyl bonds were formed due to the increasing of oxygen content. Contact angle analysis showed that the wettability of blood on the ORC film surface was better than that of the regenerated cellulose film, which was beneficial for the blood to spread. SEM images showed that the ORC film oxidized for 40 h could adsorb and activate more platelets and erythrocytes. Hemostatic evaluation and enzyme linked immunosorbent assay indicated that the ORC film had a dramatic hemostatic performance, and the products of platelets release reaction, activated platelets glycoprotein and activated clotting enzymes increased simultaneously. Moreover, the mechanism of the hemostasis for ORC film was discussed:(1) When the ORC film was applied to the bleeding wound, it could absorb most of the liquid in the blood, it also accelerated the concentration of blood. Afterwards, the carboxyl on the surface was exposed and carries electric charge which could rapidly attract and activate the platelets, and promote the generation of thrombin;(2) The carboxyl groups on ORC had strong complexation ability to the Fe2+ at the ferrous state which sited in the middle of the heme in blood, this led to nonspecific aggregation of platelets and generating an artificial clot.Collagen, one of the most biocompatible material in nature, is widely used in wound healing and organ repair. However, the limited antibacterial property and biological effectiveness of collagen limit its application as hemostasis and filling materials in dental treatment. In this study, the ultra-porous collagen(Col)/oxidized regenerated cellulose(ORC) composites were prepared. SEM photographs showed that the fasciculate ORC fibers were dispersed evenly into the reticulate structure of Col sponge. The FT-IR spectra of Col-ORC composites were quite different from those of ORC, but were similar to Col. Physical property testing results indicated that the Col had the highest tensile strength, and the Col-0.25% ORC performed optimum wettability, porosity and water absorption. MTT assay proved that the Col and Col/ORC possessed no cytotoxicity on living cells. The hemostatic time and the amount of bleeding in two injury models revealed that Col-0.25% ORC had better outstanding biological effectiveness and antibacterial property, which could be degraded completely without inflammatory reaction after 3 weeks. Moreover, the possible hemostatis mechanism was discussed based on the ELISA analysis and physico-chemical properties:(1) the ultra-porous collagen sponge could absorb a mountain of blood and concentate the blood;(2) The carboxyl groups on ORC would activated and gathered the platelets;(3) The extrinsic coagulation system could be activated. This hemostatic mechanism of Col/ORC composite combined physical adsorption and physiological hemostasis, which were conducted by collagen and ORC powders at the same time.During the wound healing process, the contractile activity of myofibroblasts was different from fibroblasts in active transforming growth factor β1(TGFβ1) conditions. In wound dressing biomaterials, it is crucial to mimic the extracellular matrix to deliver the right amount of TGFβ1 in a spatiotemporally controlled manner. We report here, for the first time, a zero-order, sustained TGFβ1 release from electrospun biomimetic nanofibers realizing optimal cell viability and myofibroblast differentiation capacity, confirmed by cell metabolic activity CCK assay, gene expression level through real-time PCR and protein expression level through immunochemical staining. At the same time, the microstructure of membrane and antibacterial performance after adding T4 phages in the electrospun biomimetic nanofibers were also studied. The results showed that PCL-Col I B hemostatic repaired membrane(40%/60%, w/w) had the best ability to stimulate cell differentiation, better hemostatic effect, excellent antibacterial properties and appropriate degradation rate in vivo.