發(fā)布時(shí)間：2018-08-01 08:18

【摘要】：聚乙烯醇(PVA)水凝膠具有彈性高、化學(xué)性質(zhì)穩(wěn)定、易于成型、無毒副作用及良好的生物相容性,在生物醫(yī)學(xué)領(lǐng)域具有廣泛的應(yīng)用,如作為緩釋載體、組織工程支架、人工器官、人工軟骨等。作為智能材料的一種,自從發(fā)現(xiàn)PVA具備形狀記憶效應(yīng)后,在過去的15年中PVA在很多領(lǐng)域得到了發(fā)展。這種熱致感應(yīng)型形狀記憶性高分子凝膠在藥物緩釋,仿生材料(動(dòng)物的肌肉體系也是一個(gè)智能型聚合物凝膠體系,通過肌肉的收縮與舒張可以把化學(xué)能轉(zhuǎn)化為機(jī)械能),智能控制等領(lǐng)域具有許多潛在的應(yīng)用價(jià)值。但是,此類材料最重要的缺陷就是力學(xué)性能差,制約了它在生物醫(yī)用方面的發(fā)展。為了改善其力學(xué)性能,很多研究者探索并實(shí)踐了各種途徑,在保持材料生物活性的前提下提高其力學(xué)性能。例如：采用不同交聯(lián)方法制備PVA凝膠、對(duì)基體PVA改性或構(gòu)建無機(jī)粒子增強(qiáng)的PVA復(fù)合材料。目的都為一個(gè)：保證良好的生物相容性、提供適宜的力學(xué)性能,使其更好更廣的被應(yīng)用,更快更早的為醫(yī)療所需為人類服務(wù)。以此為出發(fā)點(diǎn),本論文進(jìn)行了下面的探索性實(shí)驗(yàn)。 實(shí)驗(yàn)中選取以羥基磷灰石(HA)為無機(jī)粒子,構(gòu)建HA/PVA形狀記憶復(fù)合材料,以改善形狀記憶PVA水凝膠的力學(xué)性能。HA屬于生物陶瓷,其化學(xué)成份和晶體結(jié)構(gòu)與脊椎動(dòng)物的牙齒、骨組織中的無機(jī)成分相似,具有優(yōu)良的生物親和性,與骨組織極易結(jié)合,生物相容性好,更重要的是對(duì)人體組織無任何的毒副作用。實(shí)驗(yàn)采用一種新的原位生長(zhǎng)法制備形狀記憶HA/PVA復(fù)合材料,并對(duì)材料的結(jié)構(gòu)和性能以及均一性進(jìn)行了分析,從分子上探討了HA均勻形核的機(jī)理,探討復(fù)合材料的形狀記憶性能,考察復(fù)合材料的形狀記憶特性參數(shù),探究復(fù)合材料的形狀記憶機(jī)理。其主要結(jié)論如下： 1.采用原位生長(zhǎng)法制備了形狀記憶HA/PVA復(fù)合材料,并對(duì)復(fù)合材料的結(jié)構(gòu)和性能進(jìn)行了表征。結(jié)果顯示：添加氨水礦化結(jié)晶的過程中,凝膠中礦化結(jié)晶的無機(jī)粒子為HA粒子,直徑大約1μm,均勻的分散在PVA基體中,且具有毛刺狀的微觀結(jié)構(gòu)。復(fù)合材料的力學(xué)強(qiáng)度以及熱穩(wěn)定性隨著HA含量的增加而得到改善。 2.對(duì)材料的均一性進(jìn)行了分析,證明了材料具備良好的均一性。實(shí)驗(yàn)過程中,PVA溶液中所添加的HA粉體溶解所產(chǎn)生的Ca2+和PVA分子中的羥基之間形成一種配位結(jié)構(gòu),形成螯合物。當(dāng)凝膠交聯(lián)完全,加入氨水礦化結(jié)晶時(shí),Ca2+和PO43-很少向氨水中擴(kuò)散,幾乎所有的Ca2+和PO43都嵌入凝膠中,在凝膠中原位形核長(zhǎng)大。 3.探討復(fù)合材料的形狀記憶性能,考察復(fù)合材料的形狀記憶特性參數(shù),探究復(fù)合材料的形狀記憶機(jī)理。所有復(fù)合比的凝膠試樣都在室溫中晾干至常量后,形狀記憶行為的實(shí)驗(yàn)結(jié)果顯示,不同復(fù)合比例的HA/PVA復(fù)合材料都表現(xiàn)出了令人滿意的形狀記憶效應(yīng),復(fù)合材料的形狀固定率都在93%以上,形狀記憶回復(fù)率都是在90%左右；材料的回復(fù)溫度在Tg以上時(shí),復(fù)合材料回復(fù)速率加快；復(fù)合材料大概在40S左右都能回復(fù)完全,循環(huán)形狀記憶實(shí)驗(yàn)表明復(fù)合材料具有良好的循環(huán)利用價(jià)值。 4.體外細(xì)胞實(shí)驗(yàn)中發(fā)現(xiàn)HA在PVA凝膠中的原位生長(zhǎng)改善了復(fù)合材料的生物相容性,表現(xiàn)為更好的成骨細(xì)胞黏附以及細(xì)胞增殖活性。
[Abstract]:Polyvinyl alcohol (PVA) hydrogels have high elasticity, stable chemical properties, easy to form, non-toxic side effects and good biocompatibility. It is widely used in the biomedical field, such as a sustained-release carrier, tissue engineering scaffold, artificial organ, artificial cartilage and so on. As one of the intelligent materials, the shape memory effect of PVA has been found. In the past 15 years, PVA has developed in many fields. This thermo induced shape memory polymer gel is controlled by drug release. Biomimetic materials (the animal's muscle system is also an intelligent polymer gel system, through muscle contraction and relaxation can convert chemical energy into mechanical energy), intelligent control and other fields. Many potential applications. However, the most important defect of this kind of material is the poor mechanical performance, which restricts its development in biology and medicine. In order to improve its mechanical properties, many researchers have explored and practiced various ways to improve their mechanical properties on the premise of maintaining the biological activity of the materials. For example, the use of different crosslinking methods. The preparation of PVA gels, the modification of matrix PVA or the construction of PVA composites reinforced with inorganic particles. The aim is to guarantee good biocompatibility, provide suitable mechanical properties, make it better and more widely used, and serve the human being faster and earlier for medical treatment.
In the experiment, hydroxyapatite (HA) was selected as inorganic particle to construct HA/PVA shape memory composite to improve the mechanical properties of shape memory PVA hydrogel,.HA belongs to bioceramics. Its chemical composition and crystal structure are similar to the inorganic components in the teeth of vertebrates and bone tissue, with excellent biological affinity and very easy to bone tissue. The combination, good biocompatibility, and more important is no toxic and side effects on human tissues. A new in situ growth method was used to prepare shape memory HA/PVA composite. The structure, properties and homogeneity of the material were analyzed. The mechanism of HA homogeneous nucleation was discussed and the shape memory of the composite was discussed. It is possible to investigate the shape memory properties of composite materials and explore the mechanism of shape memory.
1. the shape memory HA/PVA composites were prepared by in situ growth method, and the structure and properties of the composites were characterized. The results showed that in the process of adding the mineralized crystallization of the ammonia water, the mineralized and crystallized inorganic particles in the gel were HA particles, the diameter was about 1 m, and the particles were dispersed in the PVA matrix and had the burr like microstructure. The mechanical strength and thermal stability of the composites improved with the increase of HA content.
2. the homogeneity of the material was analyzed, which proved that the material had good homogeneity. During the experiment, a kind of coordination structure was formed between the Ca2+ and the hydroxyl groups in the PVA molecule produced by the dissolution of HA powder in the PVA solution. When the gel was crosslinked completely and added into the mineralized crystallization of the ammonia water, the Ca2+ and PO43- rarely moved to the ammonia water. Almost all Ca2+ and PO43 were embedded in the gel, and grew in the gel in situ.
3. the shape memory properties of composite materials are investigated, and the shape memory properties of the composites are investigated and the shape memory mechanism of the composites is explored. All the composite gel specimens are dried to the constant at room temperature. The experimental results of shape memory behavior show that the HA/PVA composites with different composite ratios are satisfactory. The shape memory effect of the composite is more than 93%, and the recovery rate of shape memory is about 90%. When the recovery temperature of the material is above Tg, the recovery rate of the composite is accelerated, and the composite material can be recovered around 40S. The cyclic shape memory experiment shows that the composite has a good recycling use. Value.
4. in vitro cell experiment, it was found that the in situ growth of HA in PVA gel improved the biocompatibility of the composite, which showed better osteoblast adhesion and cell proliferation activity.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類號(hào)】：TB332

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