Prepareation And Evaluation Of New Nano-Bacterial Cellulose Medical Materials

Bacterial Cellulose (BC) is a kind of pure cellulose generated by microorganisms. It’s a new nano-biomaterial since its distinct physical and chemical properties have endowed it with extremely good mechanical strength and biocompatibility. It has been used in many kinds of fields, such as food, papermaking, speaker vibration film, oil exploitation, environmental protection, biomedical materials, etc. It has become a hot research topic all over the world. The medical application of bacterial cellulose is mainly focused on wound dressing and artificial blood vessel.Now, it has been a hot researched field to develop bacterial cellulose to high value-added wound dressings. Traditional gauze is most commonly used as wound dressing, but it is limited to be applied in high value-added products because of the several drawbacks such as poor water absorption, poor moisturizing abiliy, low drug loading capacity and the second trauma for patients when replacing dressing. In other side, pure BC film has a limited application on wound dressing due to its low production efficiency, high production cost, and poor mechanical performance. This project proposed a new technology, which in-situ synthesizes BC/gauze composite materials through the cultivation mode of "meta-dynamic". The composite material is characterized as the advantages of both bacterial cellulose film and gauze. On the one hand, it can improve gauze’s water absorbability, moisturizing performance, drug loading capacity and physical block performance if it is coated with a layer of the ultra-fine mesh structure nano-cellulose; On the other hand, it will enhance BC film’s mechanical property, and improve production efficiency as cultivation mode of "meta-dynamic" is designed based on the habit of BC producing strains (Acetobacter xylinum). It has brought us a new idea for the application of bacterial cellulose fiber in the wound dressing. The related properties of BC/gauze composite have been characterized. At the same time, after immersed in benzalkonium chloride aqueous solution, BC/gauze composite was endowed with antibacterial properties. Thereafter, the drug loadings, slow-release effect and antibacterial properties of this new wound dress were tested.Bacterial cellulose (BC) itself doesn’t have any antibacterial property. There are many scholars who tried to make BC wound dressing through adding antibiotics (nano-silver, chitisan). This method is generally realized by post-processing, which not only increases processes leading to high cost, but also cannot protect wound for a long period since the wound dressing cannot release antibacterial and bacteriostat for long periods of time owing to the physical adsorption of drugs in BC films. In addition, a method for in-situ synthesized BC wound dressing through direct addition of antibiotics in the fermentation culture media would not succeed since the antibiotics inhibit the growth of bacteria and formation of bacterial cellulose. In this project a chitosan/BC/gauze composit was successfully synthesized in-situ through "meta-dynamic fermention".and was characterized by using IR.The search for new replaceable blood vessel materials has been research hotspot. For nearly30years, many people have devoted to this field. At present, big-diameter vascular graft has obtained a good effect in clinical application, but ordinary small-bore artificial vascular almost has no resistance to thrombosis. Common medical artificial vascular material is hydrophobic material, which is easy to interact with plasma protein to form mural thrombus. Based on BC excellent biocompatibility, and its antithrombotic performance, bacteria cellulose becomes the research hotspot.Oxygen-permeable silicone tubings are adopted frequently when tubular bacterial cellulose is synthesized by microorganism in static fermentation. But static fermentation has some limitations and shortage, such as the limitations in the length and thickness of tubular materials, long fermentation cycle, and the stratification phenomenon in static fermentation and so on. The surface of tubular cellulose is not well-proportioned with "meta-dynamic fermention" method used in our lab. This project propsed a strategy to use displaceable culture medium to improve the uniformity of cellulose tube, and to use oxygen-rich culture medium to enhance the yield of BC tube. However, in general, mechanical property of bacterial cellulose tubular material is the fatal weakness for application. Therefore a new kind of blood vessel, which consists of an artificial fiber blood vessel coated with one layer of anticlotting bacterial cellulose,was developed, and then explored preliminarily by making use of "meta-dynamic" cultivation mode and static casing method.