24 resultados para PBT

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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Persistent bioaccumulative toxins (PBTs) are organic substances that are persistent, bioaccumulative and can cause severe toxic effects (e.g. potential oncogens, mutagenic, endocrine disrupters) to human health or environment which are the ones that need special attention. PBT chemicals could be released to the environment from several types of sources and are ubiquitous in environment. However, fast and efficiency monitoring and assessment methods to investigate PBTs in environment are still lacking. In this study, a cleaning-up procedure of analyzing PBTs in fuels combustion soot was developed and its performance was assessed through comparing the chromatograms of crude extracts with their cleaned extracts after the cleaning-up procedure. The results showed that polycyclic aromatic compounds (PACs) were the main components in fuel combustion soot and the clean-up procedure developed in this paper can be well used as the method of analyzing PBTs in fuels combustion soot.

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聚对苯二甲酸丁二醇酯(PBT)是一种多用途的工程塑料。本文中,主要研究了PBT/Epoxy(E)合金及PBT/ABS-g-GMA/E合金的结晶行为和力学性能。 使用示差扫描量热法对PBT/Epoxy合金的等温结晶过程进行了研究。发现PBT和E03 609环氧树脂在所研究的组成范围内完全相容。环氧树脂起到异相成核剂的作用,使PBT产生更强的瞬间结晶三维生长趋势。PBT和环氧树脂的Flory相互作用参数为负值,说明PBT和环氧树脂形成了热力学上的稳定混合物。 使用几种方法对PBT/Epoxy合金的非等温结晶过程进行了研究,Ozawa方程不能充分描述PBT/Epoxy合金的非等温结晶过程;使用莫志深等人提出的方法,成功地描述了该过程。实验结果显示1%环氧树脂可使PBT/Epoxy合金结晶速率明显增加。 对PBT/Epoxy合金的热和力学性能进行了研究。1%环氧树脂的加入提高PBT/Epoxy合金的缺口冲击强度20%;从红外光谱分析,环氧树脂与PBT发生了相互作用;环氧树脂影响了PBT/Epoxy合金的力学性质和结晶行为。 采用乳液聚合技术将甲基丙烯酸环氧丙酯(GMA)引入到ABS的壳层,合成了环氧官能化的ABS共聚物(ABS-g-GMA),将环氧树脂加入到PBT/ABS-g-GMA合金中,利用环氧官能团与PBT端羧基/羟基的反应达到增容PBT/ABS合金的目的。当环氧树脂的含量为5%时,PBT/ABS-g-GMA/E共混物比PBT/ABS-g-GMA共混物有更优异的力学性质。 研究了聚亚丙基碳酸酯(PPC)和聚丁二酸二甲酯(PBS)共混物的相容性、结晶和力学性能。结果显示组份PPC/PBS(90/10)可能产生部分相容。采用偏光显微镜观察了PPC/PBS共混物的形态,对于90/10 PPC/PBS共混物,发现很大数量的PBS小球晶分散在PPC基质中。力学结果显示90/10 PPC/PBS共混物拉伸强度比纯PPC提高了30%,冲击强度提高了11%。

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本工作采用熔融反应接枝的方法将(3-异氰酸酯基-4-甲基)苯氨基甲酸-2-丙烯酯(TAI)引入到聚苯乙烯-b-聚(乙烯-co-丁烯)-b-聚苯乙烯三嵌段共聚物(SEBS)上,以实现SEBS的功能化。红外光谱表明TAI已经成功接枝到SEBS上。GPC测试表明接枝后SEBS具有高的分子量与宽的分子量分布。DMA分析证明,接枝后聚(乙烯-co-丁烯) (PEB)段的玻璃化转变提高。对未参与接枝的单体的分析表明,单体TAI是个不容易自聚的单体,并对接枝过程的机理进行了研究。 为了提高TAI的存储稳定性和解决反应过程中的毒性大的问题,采用己内酰胺为封端剂对TAI中的异氰酸酯进行了封端。红外光谱和核磁共振结果表明,己内酰胺封端的TAI(BTAI)中含有双键和封闭型异氰酸酯结构,不存在着活泼的异氰酸酯。红外光谱结果表明,在高温下BTAI可以重新产生活泼的异氰酸酯基团。DSC与TG/DTA研究证明,BTAI的初始解离温度大约为135 C。采用熔融反应接枝的方法将BTAI接枝到SEBS和乙烯-辛烯共聚物(POE)分子上。研究表明,接枝率随着单体含量或引发剂含量的增加而增加。接枝以后的SEBS与POE的剪切变稀行为都比未接枝的SEBS与POE要明显。 利用BTAI功能化的SEBS和POE两种弹性体,通过熔融反应共混方法制备了PA6合金。两种弹性体与PA6共混物的红外光谱和流变行为的研究表明,在反应共混中形成了新的接枝共聚物。共混物的脆断面的场发射扫描电镜照片表明,共混物形成一种海-岛结构,而反应共混物的具有更均匀的粒子分散性,更小的粒子尺寸。PA6/SEBS-g-BTAI共混的透射电镜照片说明,共混物中形成了一种以PS为核-PEB为壳的核壳结构。与相应的物理共混物相比,通过反应共混制备的PA6合金(PA6/SEBS-g-BTAI合金和PA6/POE-g-BTAI合金)的拉伸强度、杨氏模量得到了提高。两种反应共混物的缺口冲击强度得到了非常明显的提高,合金材料的缺口冲击强度可以达到1000 J/m 以上。共混物中弹性体对PA6的结晶起到了成核的作用,结晶温度提高。形成的共聚物阻碍了PA6的分子链的运动,使得PA6的结晶温度下降。 本工作还利用上述制备的POE-g-BTAI和SEBS-g-BTAI两种功能化的弹性体与聚对苯二甲酸丁二醇酯(PBT)进行共混。研究表明,在反应共混过程中PBT中的反应基团与释放出的异氰酸酯发生反应,生成了新的共聚物。通过共混物的脆断面的FESEM图片可以看到,POE与PBT的共混物中,POE以球状粒子分散在PBT中,并且反应共混物的粒子分散均匀,粒子尺寸变小。与POE/PBT共混不同的是,在PBT与SEBS共混过程中,二者形成了交错结构,而反应共混在较低含量就形成了交错结构。POE与PBT反应共混物的缺口冲击强度得到了很大的提高,冲击强度可以达到1100 J/m以上,而PBT与SEBS的反应共混物的冲击强度改变不大。相对于物理共混物,两种弹性体与PBT的反应共混物的拉伸强度与拉伸模量都得到了提高。弹性体的加入提高了PBT的结晶温度,反应共混物的结晶温度低于物理共混物的结晶温度,说明弹性体的加入起到了PBT的成核剂的作用,生成的共聚物亦阻碍了PBT的分子链的移动。 关键词:聚苯乙烯-b-聚(乙烯-co-丁烯)-b-聚苯乙烯三嵌段共聚物;乙烯-辛烯共聚物;封闭型异氰酸酯;反应加工;聚酰胺6;聚对苯二甲酸丁二醇酯

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以过氧化二异丙苯(DCP)为引发剂,甲基丙烯酸缩水甘油醋(GMA)为活性单体对HIPS进行熔融接枝,制得了功能化的高抗冲苯乙烯(HIPS-g-GMA)。比较HIPS-g-GMA和纯的HIPS的红外谱图,可以看到在HIPS-g-GMA的谱图上出现了一个新的吸收峰,即1730cm~(-1)处的C=O的伸缩振动吸收峰,它为接枝的GMA中的醋基基团的特征峰,因此可以确定GMA己经接枝到HIPS上。能谱分析也提供了相似的结论。同时研究了单体浓度和DCP用量对产物接枝率的影响。用化学滴定方法测定了接枝物的接枝率。随着GMA量的增加,接枝率也随之增加,当GMA用量超过14%时,接枝率趋于平缓;接枝率随DCP量增加而增加。采用DSC、SEM, WAXD, DMA及力学性能等方法和手段研究PBTIHIPS和PBT/HIPS-g-GMA二元共混体系的结晶、形态结构、动态力学性能及力学性能随组成的变化。当PBT为分散相,在增容体系中的PBT出现了分级结晶现象,结晶温度降低,这是由于分散相更为精细的结果。DMA结果表明,在PBTIHIP S-g-GMA体系中由于发生了化学反应,有接枝共聚物生成,体系中两个聚合物的Tg松弛均出现了较明显的降低,增容后体系的力学性能有显著提高。采用DSC, SEM, DMA及力学性能等方法和手段研究PBT/HIPS/HIPS-g-GMA三元共混体系的结构与性能。结果表明PBT无论是分散相还是连续相,HIPS-g-GMA的作用表现为:(1)对PBTIHIPS体系的熔融和结晶行为产生了明显的影响,使PBT的结晶速率变慢,结晶度降低,结晶尺寸分布变宽,结晶完善性变差;(2)改善了共混体系的相容性。未增容体系的形态结构为锐型界面,分散相粒子同基材相连接处清晰缝隙表明两组分间界面粘接很差,为典型的不相容两相形态结构;而加入功能化接枝物的体系的分散相粒子明显变小且分布均匀,甚至难以分辨两相结构的界面;(3)提高了体系的力学性能。在多官能团单体存在下,辐照对PBTIHIPS产生影响。(1)对共混体系的熔融和结晶行为产生影响,使共混体系中的PBT的熔点降低,熔程变宽,结品度下降,结晶速率变慢,结晶尺寸分布变宽,结晶完善性变差;(2)辐射引发多官能团单体反应,使体系的两个Tg松弛发生内移,表明体系的相容性得到改善;(3)当PBT为连续相时,辐射引发的多官能团单体反应对体系的形态结构影响不如化学增溶剂HIPS-g-GMA的效果显著,含有TMPTA的体系的形态结构要好于TAIL o当PBT为分散相,体系的形态结构变化很大,分散相尺寸明显变下小,且分布均匀;(4)辐射改性能提高PBT为分散相的共混体系的力学性能。利用DSC研究了不同成核剂对生物降解聚合物PHBV的结晶性能的彩响。结果表明:(1)添加的成核剂均能影响PHBV的结晶和熔融行为,提高PHBV的结晶速率和使PHBV的结晶更加完美;(2)所有的成核剂均能降低PHBV的结晶自由能;(3)成核剂对PHBV的影响依次为BN, talc, Tb_2O_3和La_2O_3。

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本工作用反应挤出接枝的方法,以甲基丙烯酸环氧丙醋和丙烯酸为单体,有机过氧化物为引发剂,对聚乙烯进行了宫能化。对文献中各种测定PE-g-GMA中GMA含量的方法进行了比较和改进,提出了一种操作较为简单可靠的方法米测定PE-g-GMA中GMA的含量。研究了单体、引发剂浓度、反应时间和反应温度对接枝率和凝胶含量的影响。引发剂浓度对交联反应的影响最大,存在一个引发剂浓度的临界值,超过这一数值,则聚乙烯熔融接枝会产生大量的凝胶。加入给电子试剂,如对-苯醌,亚磷酸三苯醋,四氯化碳等,可以使凝胶含量由17%降低到1%左右,而接枝率只有轻微的下降,由1%降低到0.8%。在低引发剂浓度和单体浓度的情况下,加入油酸可以使接枝率有显著的提高,由0.1提高到0.7%。在过氧化物引发剂中加入秋兰姆化合物,可以使自由基引发接枝反应和交联反应的程度降低,接枝率由1%降低到0.2%,熔体流动速率由0.2提高到8。而苯乙烯的加入可以使接枝率有明显的提高,由0.8%提高到1.4%。官能化聚乙烯的结晶速率随接枝率的增加而增加,但是其结晶熔融烩随接枝率的增加而降低。原因可能是接枝链既起到了成核剂的作用,又抑制了PE的结晶生长过程。对PBTILLDPE-g-AA共混物的力学性能研究表明,其断裂伸长率和冲击强度与PBTILLDPE相比有了明显提高,断裂伸长率最高可以提高5倍,非缺口冲击强度提高幅度也很大,当LLDPE-g-AA接枝率为1%时,样条未能冲断,而PBTILLDPE只有在组成为30170时才发生部分断裂,其余组分样品则完全发生脆性断裂。增容后的共混物的拉伸强度略有改善。这说明接枝到LLDPE上的AA中的竣基与PBT的端经基存在较为强烈的相互作用,使官能化的LLDPE与PBT的相容性得到了提高,从而使共混物的韧性得到了大幅度改善,强度和模量则略有改善。对共混物的形态观察表明,随共混物中LLDPE含量的增加,作为分散相 的LLDPE的粒子尺寸逐渐增加,尺寸分布也不均匀,而当共混物中加入LLDPE-g-AA后,作为分散相的LLDPE-g-AA的粒子尺寸与LLDPE相比减少了一半左右,尺寸分布也更加均匀。尽管加入LLDPE-g-AA使共混物的相容性得到改善,但当PBT作为连续相存在时,共混体系仍然表现为脆性断裂,只有当LLDPE为连续相时,共混物才表现为韧性断裂。增容后的共混物在裂纹引发区表现出塑性变形的特征,而在裂纹的不稳扩展区仍然为脆性断裂,说明相容性的改善主要是提高了共混物的裂纹引发能和稳定扩展能,因此共混物的非缺口冲击强度提高非常明显。另外在拉伸的情况下,相容性的改善使材料出现宏观的剪切屈服成颈的现象,从而使断裂能大幅度提高。加入LLDPE到PBT中,抑制了PBT的正常球晶的形成,使PBT球晶中正常球晶的含量降低,这种效应随LLDPE-g-AA中AA含量的增加而增加,而对总的结晶度的影响较小,说明共混物两组分之间的相互作用主要是使PBT的结晶形式受到影响。对官能化聚乙烯蠕变行为和动态流变行为的研究表明,官能化聚乙烯的零切粘度(3.9 * 10~4Pa.s)要高于纯聚乙烯(1.28 * 10~4Pa.s),其熔体弹性也有显著提高,这不仅是由于分子量增加造成的,而且对接枝率比较高的官能化聚乙烯,也存在长支链的影响。共混物的粘度与共混物组成的关系在低剪切应力的情况下,符合Utracki方程。高剪切应力条件下,共混物的形态沿毛细管径向位置不同发生改变导致Utracki方程失效。Utrackl方程中的表征界面滑移因子的参数刀不仅与剪切应力有关,而且与两组分的粘弹性有关。

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The miscibility and the isothermal crystallization kinetics for PBT/Epoxy blends have been studied by using differential scanning calorimetry, and several kinetic analyses have been used to describe the crystallization process. The Avrami exponents n were obtained for PBT/Epoxy blends. An addition of small amount of epoxy resin (3%) leads to an increase in the number of effective nuclei, thus resulting in an increase in crystallization rate and a stronger trend of instantaneous three-dimensional growth. For isothermal crystallization, crystallization parameter analysis showed that epoxy particles could act as effective nucleating agents, accelerating the crystallization of PBT component in the PBT/Epoxy blends. The Lauritzen-Hoffman equation for DSC isothermal crystallization data revealed that PBT/Epoxy 97/3 had lower nucleation constant K, than 100/0, 93/7, and 90/10 PBT/Epoxy blends. Analysis of the crystallization data of PBT/Epoxy blends showed that crystallization occurs in regime II. The fold surface free energy, sigma(e) = 101.7-58.0 x 10(-3) J/m(2), and work of chain folding, q = 5.79-3.30 kcal/mol, were determined. The equilibrium melting point depressions of PBT/Epoxy blends were observed and the Flory-Huggins interaction parameters were obtained.

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The modification of high-impact polystyrene (HIPS) was accomplished by melt-grafting glycidyl methacrylate (GMA) on its molecular chains. Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis were used to characterize the formation of HIPS-g-GMA copolymers. The content of GMA in HIPS-g-GMA copolymer was determined by using the titration method. The effect of the concentrations of GMA and dicumyl peroxide on the degree of grafting was studied. A total of 1.9% of GMA can be grafted on HIPS. HIPS-g-GNU was used to prepare binary blends with poly(buthylene terephthalate) (PBT), and the evidence of reactions between the grafting copolymer and PBT in the blends was confirmed by scanning electron microscopy (SEM), dynamic mechanical analysis, and its mechanical properties. The SEM result showed that the domain size in PBT/HIPS-g-GMA blends was reduced significantly compared with that in PBT/HIPS blends; moreover, the improved strength was measured in PBT/HIPS-g-GMA blends and results from good interfacial adhesion. The reaction between ester groups of PBT and epoxy groups of HIPS-g-GMA can depress crystallinity and the crystal perfection of PBT.

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The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEM and optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends, The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1% LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation.

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以过氧化二异丙苯 (DCP)为引发剂 ,甲基丙烯酸缩水甘油酯 (GMA)为活性单体 ,高抗冲苯乙烯(HIPS)通过熔融接枝制得了功能化的高抗冲聚苯乙烯接枝物 (HIPS g GMA)。用红外光谱和电子能谱对其结构进行了表征。HIPS g GMA的红外谱图 ,证明GMA已经接枝到HIPS上。电子能谱分析也提供了相似的结论。研究了单体浓度和DCP用量对产物接枝率的影响 ,并用化学滴定方法测定了接枝物的接枝率。用DSC、SEM、WAXD、DMA等研究了PBT/HIPS和PBT/HIPS g GMA的结晶、形态结构、动态力学性能及力学性能随组成的变化。SEM及DMA分析表明增容后体系的相容性得到改善 ,力学性能有较大提高。

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Irradiation can be applied to crosslink the dispersed elastomer phase to increase the modulus and decrease the voiding ability of the elastomer, which results in increasing critical brittle-tough transition elastomer content at constant temperature. The experimental results show that at 25 degrees C the critical elastomer content of EPDM shifts to higher composition (shift of about 4 wt%) for PBT/EPDM blends after 100 kGy gamma-irradiation. (C) 1997 Elsevier Science Ltd.

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The concept of an extended fractional Fourier transform (FRT) is suggested. Previous PBT's and complex FRT's are only its subclasses. Then, through this concept and its method, we explain the physical meaning of any optical Fresnel diffraction through a lens: It is just an extended FRT; a lens-cascaded system can equivalently be simplified to a simple analyzer of the FRT; the two-independent-parameter FRT of an object illuminated with a plane wave can be readily implemented by a lens of arbitrary focal length; when cascading, the Function of each lens unit and the relationship between the adjacent ones are clear and simple; and more parameters and fewer restrictions on cascading make the optical design easy. (C) 1997 Optical Society of America.

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本工作通过电子束预辐照处理和反应挤出方法,制备了丙烯酸功能化预辐照聚丙烯rPP-g-AA,采用化学滴定和红外光谱方法均证明接枝共聚物的存在,同时确定了预辐照剂量和单体浓度对接枝率的影响:(1)当单体浓度一定时,接枝率随预辐照剂量的增加而增加并逐渐达到平台值;(2)当预辐照剂量固定时,单体浓度在0~4.0wt%范围内,接枝率几乎呈线性增加。研究发现,丙烯酸(AA)接枝链能起到异相成核作用而促进预辐照聚丙烯(rPP)的结晶过程,但却不改变结晶晶型;虽然接枝反应可以部分抑制降解反应,但相对于原料聚丙烯(PP),接枝产物的力学性能仍大大下降;因此提出的反应机理认为接枝反应主要是通过链断裂降解反应形成的端自由基引发的,从而形成了以端基接枝为主的产物。 为了控制PP接枝过程中的严重降解,本工作首次提出了均相和异相引发接枝反应的原理,即采用部分rPP和预辐照聚乙烯(rPE)分别作为PP接枝反应的均相和异相“引发剂”,经反应挤出制备丙烯酸功能化聚丙烯PP-g-AA。对于均相引发体系:(1)当rPP用量为20phr时,PP-g-AA的接枝率已经达到rPP-g-AA的水平,而且降解反应得到有效控制;(2)和PP/rPP-g-AA共混物的对比研究证明,均相引发接枝产物不但接枝率明显提高,而且接枝分布非常均匀;(3)由此提出均相引发主要是发生rPP和PP分子间夺氢反应并形成以基体PP接枝为主的产物,而rPP分子内夺氢反应形成的接枝产物rPP-g-AA只占较少比例。对于异相引发体系: (1)通过红外光谱表征及接枝率计算得出异相引发接枝产物的接枝率比相应的PP/ rPE-g-AA共混物略高;(2)由于rPE及rPE-g-AA对基体PP的结晶没有影响,通过异相引发接枝产物中PP的结晶温度升高直接验证了异相引发接枝反应的实现;(3)提出的机理认为异相引发主要发生在rPE的分子内夺氢并形成rPE-g-AA,造成rPE引发的PP分子间夺氢反应形成PP-g-AA产物的比例下降。 本工作还详细研究了rPP预辐照剂量、rPP用量和单体浓度对均相引发反应的影响。得到的结果如下:(1)高预辐照剂量导致了接枝率下降的“假相”是由于形成的微凝胶造成的;(2)rPP用量的增大在提高接枝率的同时也导致降解反应的逐渐增强;(3)单体浓度的增加导致接枝率的逐步提高并最终达到最大值,而且可能导致部分微凝胶的产生;(4)接枝没有破坏PP-g-AA结晶的完善性和晶型,却能促进了晶体在(040)晶面的生长并可能产生部分横晶形态;(5)PP-g-AA和金属能形成良好的粘接作用。 以上述制备的rPP-g-AA和PP-g-AA增容PP/聚对苯二甲酸丁二醇酯(PBT)共混体系,发现高分子量的PP-g-AA比低分子量的rPP-g-AA的增容效果要好,因此认为PP-g-AA和PBT通过酯化反应形成的长链接枝共聚物PP-g-PBTPBT相的分散和界面作用增强更加有效。而随着增容剂PP-g-AA比例的增加,原位反应生成的PP-g-PBT逐渐增加,使得PBT相分散和界面增强效果更加显著,因此共混物的力学性能也更佳;DSC研究发现,随着PBT相尺寸减小到1μm以下,PBT出现了结晶受限行为。 将引发剂rPP和单体AA加入到PP/PBT共混体系中实现了一步法反应增容,得到共混物的扭矩、相形态、力学性能都和分步法增容共混物的结果几乎相同,这说明一步法共混能使PBT产生良好分散并得到性能较佳的产物,从而为高分子合金材料制备提供了一种简单有效的方法。 采用该方法对AA、马来酸酐(MAH)和甲基丙烯酸甘油酯(GMA)三种单体的接枝和增容反应对比研究证明,AA的效果最好,MAH次之,而GMA的效果最差,分析认为,AA和MAH通过接枝反应形成PP-g-AA和PP-g-MAH,随后再和PBT发生酯化增容反应形成PP-g-MAH-PBT共聚产物,而GMA首先和PBT反应形成PBT-GMA,而后由长链PBT-GMA发生接枝反应生成PP-g-GMA-g-PBT,但是这种接枝反应的效率很低,由此造成增容效果较差。

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人类的载脂蛋白A5(apolipoprotein A5,APOA5)是一个新近发现的载脂蛋白家族成员。它在血浆中的含量比其他载脂蛋白低1-2个数量级,但能显著影响血浆三酰甘油水平,对血脂代谢具有重要意义,可以作为降血脂药物治疗中一个强有力的潜在靶标。 由于APOA5在血浆中含量低,直接从血浆中分离纯化很困难,国内一直没有报道简易可靠的纯化方法。为进一步研究APOA5的生物学特性,探讨其与TG代谢中的其它关键成分之间的相互关系,揭示其在脂类代谢相关疾病中的重要地位,必须有大量的蛋白和抗体用于基础研究。因此本研究首先利用基因工程技术,诱导表达纯化APOA5蛋白,免疫动物制备多克隆抗体,为进一步研究人肝脏细胞中APOA5的相互作用蛋白,研究APOA5蛋白在肝脏细胞中的功能奠定基础。 为了深入研究APOA5在肝脏中如何行使功能,我们采用细菌双杂交技术寻找与APOA5相互作用的蛋白因子。并采用Pull-down技术,免疫荧光及免疫共沉淀技术进一步确证其在体外和体内的相互作用关系,为进一步阐明APOA5在体内的生理功能提供了新的线索。 第一部分 APOA5基因的克隆、原核表达、纯化及其多克隆抗体的制备 本研究首先应用基因克隆技术,从人肝癌细胞系SMMC-7721的cDNA中扩增出1.1 kb的ApoA5基因全长序列。然后将其克隆至表达载体pThioHisD,构建原核表达载体pTH-APOA5。该重组质粒转化至大肠杆菌 BL21(DE3),成功实现人APOA5融合蛋白在大肠杆菌中的表达。经发酵得到高效表达的融合蛋白。 融合蛋白在 IPGT 诱导下以包涵体的形式大量表达。利用融合蛋白上的一段组氨酸序列,用镍离子亲和柱进行纯化和复性后,获得较高纯度的人APOA5融合蛋白。利用该融合蛋白免疫新西兰大耳白兔,获得了高效价的兔抗人APOA5多克隆抗体,Western Blot结果显示此多克隆抗体与APOA5特异性结合。 第二部分 细菌双杂交筛选与APOA5相互作用的蛋白 本实验首先构建了pBT-APOA5重组质粒,经双酶切、PCR和测序鉴定证明重组诱饵质粒构建成功,并进行了表达、自激活鉴定。Western Blot鉴定证实报告菌株中表达了分子量为 68 kD左右的重组融合蛋白,与预测的分子量APOA5(41 kD)/lamda cI (27 kD)一致。自激活实验证明诱饵蛋白不能单独激活报告基因,可用于筛选人肝脏cDNA文库。经过双重抗性筛选和回复筛选,分离出10个阳性克隆。对结果进行生物信息学分析,得到7个与APOA5相互作用的蛋白,其中BI1为细胞凋亡调节因子;ATP6、CYTB、ND2、COX-1为线粒体表达蛋白; ALB、TTR为血清蛋白。 第三部分 APOA5与BI1相互作用的确证 首先构建了BI1的原核表达载体pGEX-5X-3-BI1,利用Pull-down实验检测了APOA5与BI1在体外具有相互作用。然后构建了BI1的真核表达载体pCDNA3.1-HA-BI1和APOA5的真核表达载体pCDNA3.1-APOA5,并验证其表达。通过免疫荧光细胞内共定位研究发现,靶蛋白APOA5主要分布于胞浆,与BI1在HEK293细胞有共定位,即APOA5与BI1存在相互作用的可能。最后利用免疫共沉淀手段,在HEK293细胞中确证了靶蛋白APOA5与BI1在体内的相互作用。 上述研究结果,为深入研究APOA5在体内的生物学功能提供了新的思路。 Apolipoprotein A5 (APOA5) is a newly discovered protein belongs to apolipoprotein family. APOA5’s concentration is 1-2 orders of magnitude lower than other apolipoproteins in the circulation. APOA5 significantly affected plasma triglyceride levels, which is important on lipid metabolism. APOA5 has strong potential to be used as a hypolipidemic drug target. Large amount of APOA5 protein and antibodies are needed in basic research, such as biological characteristics study of the APOA5, its relationship with other key components in TG metabolism, its role played in Lipid metabolism-related diseases. Due to its low concentration in plasma, separation and purification of APOA5 from the plasma is very difficult. Until now no report on simple and reliable method for purification has been published in China. In this study, we firstly got APOA5 recombinant protein using genetic engineering technology. The purified recombinant protein was used to immunize rabbits to get antiserum. It is important for further study of the APOA5 protein-interacting protein. And it lays the foundation for studing APOA5 function in liver. In order to study APOA5 function in liver, we used bacterial two-hybrid technology to find the APOA5 protein interactor. Pull-down, immunofluorescence and immunoprecipitation techniques were used to further confirm the interaction between APOA5 with its interactor in vitro and in vivo. All of these stdudies provided new clues on its physiological functions in vivo. Part I: Cloning, prokaryotic expression, purification and polyclonal antibody preparation of APOA5 First of all, we amplified APOA5 CDS sequence from the human hepatoma cell line SMMC-7721, and subcloned into Expression vector pThioHisD, and got the recombinants named pTH-APOA5. The plasmid was transformed to BL21 (DE3). E. coli BL21(DE3) cells bearing the pTH-APOA5 plasmid were cultured and APOA5 protein synthesis was induced by the addition of IPTG. Recombinant protein was expression in the form of inclusion. Inclusion bodies were dissolved in phosphate-buffered saline containing 8 M urea and 40 mM imidazole, then applied to a Ni2+ affinity column, and were eluted in a buffer containing 4 M urea and 200 mM imidazole. Fractions containing the APOA5 protein were pooled and dialyzed against buffer containing phosphate-buffered saline. Antiserum to recombinant human APOA5 was generated by immuning rabbit. Western Blot showed that this antiserum specific binding with APOA5. Part II Two-hybrid system screening protein interactions with the APOA5 The coding sequence of human APOA5 was amplified using synthetic oligonucleotide primers from pTH-APOA5 vector and was subcloned into the pBT plasmidc to yield pBT-APOA5 vector. DNA sequencing was performed to verify that no unwanted mutations occurred during the process of plasmid vector construction. We verified recombinant protein expression and tested self-activation by pBT-APOA5 prior to screening. Western Blot verified inducing a 68 kD band, consistent with the predicted molecular weight (APOA5 41 kD, lamda cI 27 kD). pBT-APOA5 can be used for screening human liver cDNA library because it can not self-activation. Totally 10 positive clones were isolated. The nucleotide sequence of the positive clones were determined and compared to NCBI nucleotide sequence databases. We got 7 protein which interact with APOA5, included BI1(Apoptosis regulator); ATP6, CYTB, ND2, COX-1(Mitochondrial protein) and ALB, TTR(Serum protein). Part III Confirming of interaction between APOA5 with BI1 pGEX-5X-3-BI1 vector was subcloned at first. Pull-down experiments were used to detect the interaction between APOA5 with BI1 in vitro. Later, pCDNA3.1-HA-BI1 and pCDNA3.1-APOA5 were subcloned. Through immunofluorescence co-localization study, we found APOA5 mainly distributed in the cytoplasm. APOA5 is co-localization with BI1 in HEK293 cells. Finally, we verified interaction between APOA5 with BI1 in vivo through immunoprecipitation.