组织工程支架材料的超声加工和检测技术
发布时间：2018-11-24 18:45
【摘要】：组织工程学的快速发展使医学即将走出器官移植的范畴,步入制造组织和器官的新时代。组织工程支架材料是组织工程学实现临床应用的重要环节,但是目前有关组织工程支架材料的制备仍存在溶剂残留和生物降解特性不可控等问题。 基于组织工程支架材料的要求,本文针对化学发泡制作技术存在的溶剂残留的毒性问题,采用无溶剂C02超临界固态发泡技术,在1-5MPa饱和压力下制备了泡孔孔径550-20μm的聚乳酸(PLA)支架材料,分析了泡孔孔径与饱和压力,发泡温度,加压时间等参数的对应关系。基于热重测量法提出了一种对组织工程PLA微孔支架材料进行泡孔孔径相关的热分解动力学特性评价和寿命估计的新方法。实验结果证明高饱和压力条件下制备的PLA支架材料具有小泡孔孔径和大泡孔密度；PLA原材料经过发泡后热稳定性下降,降解时间缩短；在较低温度下大泡孔孔径支架材料具有较低的活化能和较差的热稳定性,其分解时间缩短到原材料的几十分之一。 另外,针对闭孔支架材料的通透性差、细胞生长代谢速度慢以及降解时间不可控等问题,通过强功率脉冲超声对PLA微孔支架材料进行辐照打破泡孔壁来增强材料的通透性。首先从理论方面研究了超声空化和超声微射流技术以及PLA支架材料通透性增强原理,然后通过超声辐射实验证明了随着超声辐射强度的提高,PLA支架材料泡孔孔壁破损增强,泡孔连通性增强。另外研究了发泡材料中的声传播特性,建立了超声插入取代特性检测模型和实验系统,对超声辐射前后的发泡材料进行了声学测量,结果表明PLA支架材料的衰减系数和超声辐射强度(通透性)呈现线性增大关系,但当通透性足够大时,水能克服其表面张力进入泡孔,材料的衰减系数迅速减小。 本研究针对组织器官对支架材料的泡孔孔径和降解时间的要求,通过热分解动力学特性和声学特性的测量来反映PLA微孔支架材料的形态结构,进而优化固态发泡制作参数,为组织工程支架材料的精确设计及其降解特性的定量分析提供依据,同时本研究提出的通透性超声增强和超声检测新技术,对组织工程支架材料的性能改善和检测有着重要的应用前景。
[Abstract]:With the rapid development of tissue engineering, medicine is about to step out of the field of organ transplantation and enter a new era of making tissues and organs. Tissue engineering scaffold is an important link in the clinical application of tissue engineering. However, the preparation of tissue engineering scaffolds still has some problems such as solvent residue and uncontrollable biodegradation characteristics. Based on the requirements of scaffold materials for tissue engineering, the solvent free C02 supercritical solid state foaming technology was used to solve the toxic problem of solvent residue in chemical foaming technology. Polylactic acid (PLA) scaffolds with a bubble pore diameter of 550-20 渭 m were prepared under the saturated pressure of 1-5MPa. The relationship between the pore size and the parameters such as saturation pressure, foaming temperature and pressure time was analyzed. Based on the thermogravimetric method, a new method for evaluating the thermal decomposition kinetics characteristics and life estimation of microporous PLA scaffolds in tissue engineering is proposed. The experimental results show that the PLA scaffolds prepared under high saturation pressure have small pore size and large pore density, the thermal stability of PLA raw materials decreases after foaming, and the degradation time is shortened. At lower temperatures, the macroporous scaffolds have low activation energy and poor thermal stability, and their decomposition time is reduced to a fraction of that of raw materials. In addition, aiming at the problems of poor permeability, slow cell growth and metabolism and uncontrollable degradation time, the permeability of PLA microporous scaffolds was enhanced by strong power pulse ultrasound irradiation to break the bubble wall. Firstly, the ultrasonic cavitation and ultrasonic microjet technology and the principle of enhancing the permeability of PLA scaffold materials are studied theoretically. Then, the ultrasonic radiation experiments show that the damage of the porous wall of PLA scaffold material increases with the increase of ultrasonic radiation intensity. The connectivity of bubble pores was enhanced. In addition, the acoustic propagation characteristics in the foamed materials are studied, and the testing model and experimental system of the ultrasonic insertion substitution characteristics are established, and the acoustic measurements of the foamed materials before and after ultrasonic radiation are carried out. The results show that the attenuation coefficient of PLA scaffold material increases linearly with the ultrasonic radiation intensity (permeability), but when the permeability is large enough, the water can overcome the surface tension and enter the bubble pore, and the attenuation coefficient of the material decreases rapidly. In this study, according to the requirements of tissue and organs on the pore size and degradation time of scaffolds, the morphology and structure of PLA microporous scaffolds were reflected by the measurement of thermal decomposition kinetics and acoustic characteristics, and then the parameters of solid foam fabrication were optimized. It provides the basis for accurate design and quantitative analysis of degradation characteristics of scaffold materials for tissue engineering. At the same time, a new technology of ultrasonic enhancement and ultrasonic detection of permeability is proposed in this study. It has an important application prospect for improving the properties and testing of scaffold materials for tissue engineering.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.08
本文编号：2354635
[Abstract]:With the rapid development of tissue engineering, medicine is about to step out of the field of organ transplantation and enter a new era of making tissues and organs. Tissue engineering scaffold is an important link in the clinical application of tissue engineering. However, the preparation of tissue engineering scaffolds still has some problems such as solvent residue and uncontrollable biodegradation characteristics. Based on the requirements of scaffold materials for tissue engineering, the solvent free C02 supercritical solid state foaming technology was used to solve the toxic problem of solvent residue in chemical foaming technology. Polylactic acid (PLA) scaffolds with a bubble pore diameter of 550-20 渭 m were prepared under the saturated pressure of 1-5MPa. The relationship between the pore size and the parameters such as saturation pressure, foaming temperature and pressure time was analyzed. Based on the thermogravimetric method, a new method for evaluating the thermal decomposition kinetics characteristics and life estimation of microporous PLA scaffolds in tissue engineering is proposed. The experimental results show that the PLA scaffolds prepared under high saturation pressure have small pore size and large pore density, the thermal stability of PLA raw materials decreases after foaming, and the degradation time is shortened. At lower temperatures, the macroporous scaffolds have low activation energy and poor thermal stability, and their decomposition time is reduced to a fraction of that of raw materials. In addition, aiming at the problems of poor permeability, slow cell growth and metabolism and uncontrollable degradation time, the permeability of PLA microporous scaffolds was enhanced by strong power pulse ultrasound irradiation to break the bubble wall. Firstly, the ultrasonic cavitation and ultrasonic microjet technology and the principle of enhancing the permeability of PLA scaffold materials are studied theoretically. Then, the ultrasonic radiation experiments show that the damage of the porous wall of PLA scaffold material increases with the increase of ultrasonic radiation intensity. The connectivity of bubble pores was enhanced. In addition, the acoustic propagation characteristics in the foamed materials are studied, and the testing model and experimental system of the ultrasonic insertion substitution characteristics are established, and the acoustic measurements of the foamed materials before and after ultrasonic radiation are carried out. The results show that the attenuation coefficient of PLA scaffold material increases linearly with the ultrasonic radiation intensity (permeability), but when the permeability is large enough, the water can overcome the surface tension and enter the bubble pore, and the attenuation coefficient of the material decreases rapidly. In this study, according to the requirements of tissue and organs on the pore size and degradation time of scaffolds, the morphology and structure of PLA microporous scaffolds were reflected by the measurement of thermal decomposition kinetics and acoustic characteristics, and then the parameters of solid foam fabrication were optimized. It provides the basis for accurate design and quantitative analysis of degradation characteristics of scaffold materials for tissue engineering. At the same time, a new technology of ultrasonic enhancement and ultrasonic detection of permeability is proposed in this study. It has an important application prospect for improving the properties and testing of scaffold materials for tissue engineering.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.08
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