| Statistics released by the World Health Organization in 2017 indicate that cardiovascular disease such as atherosclerosis caused by vascular stenosis or blockage has become a huge threat to human health.Vascular transplantation is widely used as an effective means to treat these diseases.Due to the different conditions of patients,autologous blood vessel transplantation methods are very restricted.There are many deficiencies in vascular grafts taken from other organisms and used directly.Therefore,researchers have conducted a large number of researches on artificial blood vessels.Large-caliber artificial blood vessels(inner diameter ? 6mm)have achieved satisfactory results in clinical applications and have been put into commercial production;but small-caliber artificial blood vessels(inner diameter < 6mm)due to narrow diameter and poor anticoagulant properties to fail in clinical requirements.The new materials that can be suitable for small-caliber artificial blood vessels and the bionic design of small-caliber artificial blood vessel modifications have extremely important application values and broad prospects.In recent years,materials used to prepare small-caliber artificial blood vessels include natural biological materials such as Silk Fibroin,collagen,and cellulose,Synthetic materials include polyester(PET),expanded polytetrafluoroethylene(ePTFE),and polyurethane(PU),Among them,polyurethane has well water permeability,blood compatibility,and conformability to natural blood vessels,and is considered as a superior material for making vascular grafts.However,as a small-caliber artificial blood vessel,the inner wall of the blood vessel is often accompanied by problems such as thrombosis and intimal hyperplasia.In order to solve these problems,the polyurethane artificial blood vessel is further improved through electrospinning in the process of textile artificial blood vessels.Microbubbles with drug-loading functions are spun into the wall of the vessel wall,providing the possibility of solving these problems.The main research content of the thesis is listed as follows:Synthesis and Characterization of Polycaprolactone Polyurethanes:Firstly,stannous octoate was used as a catalyst,1,4-butanediamine was a chain extender,polycaprolactone diol was a soft segment,and hexamethylene diisocyanate was a hard segment to prepare polycaprolactone-based polyurethane;The soft segment composition was adjusted to use a 25:75 mass ratio of polycaprolactone diol to polyethylene glycol as a soft segment,stannous octoate as a catalyst,and 1,4-butanediamine as a chain extender.Hexamethylene diisocyanate is a hard segment to prepare polycaprolactone polyurethane ureaSynthesis and characterization of polyester microbubbles:Polycaprolactone,as a commonly used biomedical material at present,is used to prepare polyester microbubbles.First,glycolic acid is used as an initiator to initiate the ring-opening polymerization of ?-caprolactone monomers to obtain polycaprolactones with hydroxyl end groups.Then,polyester microbubbles encapsulated in bovine serum albumin were prepared using isopropyl acetate as an initiator and glutaraldehyde as a cross-linking agent.In order to facilitate traceability,fluorescent dyes were added to the hydroxyl-terminated polycaprolactone,and then the bright and dark field microscopy,scanning electron microscopy(SEM)analysis,and size distribution of the polyester microbubbles containing fluorescent dyes were performed.As well as in vitro and in vivo ultrasound visualization tests.Preparation of artificial blood vessels by electrospinning:According to the principle of electrospinning,our laboratory has designed a set of electrospinning equipment and assembled it by ourselves and used the prepared polycaprolactone polyurethane as the raw material to carry out artificial textile work. |
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