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Degradation Behaviors of Electrospun Fibers of Poly(DL-lactide) and Hydroxyapatite and the Hot-pressed Composites

Author: ZhuangHuiHui
Tutor: LiXiaoHong
School: Southwest Jiaotong University
Course: Biomedical Engineering
Keywords: Electrospinning Modified polylactic acid fiber Induced mineralization composite fiber Hot composite materials Degradation behavior
CLC: R318.08
Type: Master's thesis
Year: 2009
Downloads: 32
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Abstract

In biological materials, poly lactic acid (PDLLA) and have good compatibility, but its strength is low, the acidic degradation products, easy to cause local aseptic inflammation. Hydroxyapatite (HAp) directly bonded with the bone, is the biocompatibility of the bone repair material, but its low mechanical strength, high brittleness, flexural, and impact resistance can not satisfy the high load artificial requirements. Electro-spun fibers of the nonwoven fabric having a high porosity, large surface area, the fiber fine degree with high uniformity, large aspect ratio, etc.. PDLLA and HAp preparation of composite fiber bracket its hot press parts as tissue regeneration and repair materials, has great potential in the field of biomedical. This thesis is mainly divided into three parts, including the modified PDLLA fibers, induced mineralization fiber, the mineralization fiber hot composite material. Biodegradability is one of the key issues that need to be considered in the tissue regeneration scaffold and tissue repair materials, the papers in vitro degradation experiments investigated the degradation behavior of the three types of materials, analysis of the degradation mechanism and the main factors. Functionalized PDLLA fibers obtained through two ways, in order to solve the shortcoming of PDLLA fiber membrane surface hydrophilicity, First, through the introduction of functional groups on PDLLA macromolecules, and then electrically spun into fibers; another way is first prepared PDLLA electrically fibers was then grafted gelatin and other biological macromolecules. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectra verify the modification process, quantitative characterization of PDLLA molecular amine, hydroxyl, carboxyl and gelatin content. The results showed that the electrospun fiber diameter of about 2μm, the functional groups of the PDLLA average every 100 lactic acid monomer contained in the number of each group is about 5.6, the the fiber surfaces gelatin graft quantity 0.21μg/cm2. Functionalized PDLLA fiber vitro degradation results show that the modified PDLLA hydrophilic fibers affect the water molecules into the speed of the polymer matrix, while the hydrophobic interior of the fiber the accumulation of acidic degradation products accelerated the degradation of the matrix polymer, the above process are affected to the fiber The degradation behavior. The modified PDLLA fiber degradation after 16 weeks, the group modified fiber degradation faster, wherein the carboxyl-modified PDLLA fibers (C-PLA-F) the degradation rate is the fastest, while the gelatin modified PDLLA fibers (Gel-PLA-F) higher water infiltration, and therefore its degradation rate slightly faster than the PDLLA fiber (PLA-F). In order to improve the dispersibility of the composite fibers of hydroxyapatite, the functional group in the modified fiber and graft macromolecules induced mineralization the composite fiber membranes, the scanning electron microscope (SEM) observation showed that the surface of the fiber to induce the formation of an inorganic HAp content of about 15%, infrared spectra carboxyl and calcium ion induced nucleation in the mineralization process induced mineralization fiber presents super-hydrophilic. Vitro degradation results indicate that the carboxyl groups in the modified fibers to induce mineralization of the group parameters induced mineralization process, offset modifying group role in promoting the degradation of the polymer, the carboxyl-modified PDLLA the mineralized fiber membrane (C-PLA-M) the degradation rate of the polymer, remaining rate rate of water absorption and the weight of the inorganic substance is lower than the hydroxy carboxyl-modified PDLLA the mineralized fiber membranes (HC-PLA-M) and the amine-hydroxy-carboxyl-modified PDLLA the mineralized fiber membranes (AHC -PLA-M); the gelatin modified mineralized fiber membranes (Gel-PLA-M), the surface of the fiber HAP degradation of the polymer and absorbent fiber membrane role significantly lower. Gel-PLA-M degradation rate is relatively slow, inorganic HAp the Release on in the degradation speed up. To obtain the bone repair material to meet the requirements of clinical application, the mineralized fibers obtained under the hot pressing conditions optimized composite materials, SEM observation showed that the morphology of the fiber is maintained in the thermocompression material mechanical performance tests show, and co-blended fibers heat grading material compared to the modified fibers to induce mineralization the thermocompression composite material strength is increased, but the toughness is weakened. The in vitro degradation results show that the material remains within the fiber morphology and structure after 13 weeks. Degradation of the composite fiber hot material is significantly faster than PDLLA fiber hot press materials. Carboxyl-modified the thermocompression material of the composite fibers, the amino-hydroxy PDLLA mineralization fiber the thermocompression material (AHC-PLA-P) and the the gelatin modified PDLLA the mineralized fiber thermocompression material (Gel-PLA-P) to be slightly faster than PDLLA / HAp the the blended the fiber hot press materials (BPLA-P). Through the study, to obtain a modified PDLLA electrospun fibers can be used as a tissue regeneration scaffold and hard tissue repair materials, induced mineralization fiber and hot-pressed composite materials obtained in vitro degradation characteristics of clinical should be able to provide some technical support.

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CLC: > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > General issues > Biomaterial
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