论文标题:有序分子膜诱导下草酸钙晶体的生物矿化研究
Studies on the Biomineralization of Calcium Oxalate Crystals Induced by Organized Molecular Films
论文作者 钟玖平
论文导师 欧阳健明,论文学位 硕士,论文专业 无机化学
论文单位 暨南大学,点击次数 194,论文页数 63页File Size3677k
2003-04-01论文网 http://www.lw23.com/lunwen_1502802/ 草酸钙,单分子膜,LB膜,生物矿化
Calcium oxalate;Monolayer film;Langmuir-Blodgett film;Biomineralization
以单分子膜和LB膜作为模板，用SEM，ESEM，TEM，AFM，XRD和FT-IR等表征方法，在体外研究了草酸钙晶体的生物矿化过程。 用不同成膜物质组装形成的有序分子膜对膜／液界面形成的草酸钙晶体具有不同的诱导作用。硬脂酸单分子膜由于其亲水基团的负电性，使得COM晶体有序排列生长，晶体的两端成“尖角”状；磷脂DPPC单分子膜诱导下，草酸钙晶体的((?)01)晶面与膜平面平行生长，而且，在相同结晶时间里，磷脂DPPC单分子膜诱导下的COM晶体的粒径比本体溶液中的COM晶体粒径要大。 生物大分子C_4S作为一种内源性的尿大分子，它不仅从热力学上提高Ca~(2+)在尿液中存在的浓度，使体系中CaC_2O_4保持较高的相对过饱和度，降低草酸钙结石成核的可能性；而且在晶体生长时，抑制COM晶体晶面的二维生长和晶体聚集。 在磷脂DPPC单分子膜诱导下，草酸钙晶体的形成受膜压和添加物的影响。膜压为20mN／m时，草酸钙晶体呈现出比较规则的六棱柱形晶体。在亚相中添加各种生物分子使得草酸钙晶体的形貌发生改变：C_4S使草酸钙晶体的((?)01)晶面变成拉长的六边形，而且晶体的厚度变薄；L-Glu使草酸钙晶体棱角明显增多，形成多棱“不规则”晶体；CSA也使草酸钙晶体变薄。 将磷脂DPPC的单分子膜提拉成磷脂LB膜，并用其诱导草酸钙晶体生长。用AFM观察发现，草酸钙晶体最初在磷脂DPPC的LB膜上成核。体系中添加L-Glu和C_4S不改变COM晶体的物相，但使晶体形貌发生改变。不同形貌晶体的分布受添加物浓度的影响：C_4S浓度的增加使COM晶体由六棱柱形晶体转变为六边薄片状晶体，特别是当C_4S浓度为0.50 mg／mL时，COM晶体全部转变为六边薄片状晶体；L-Glu浓度的增加使COM晶体由六边棱柱晶体逐渐转变为多棱“不规则”晶体。 由于存在以下两个因素：1)生物细胞膜是磷脂和蛋白质形成的复合膜；2)草酸钙结石是在流动的尿液中形成的。所以，如果将实验设计成在流动体系中用磷脂和蛋白质的复合膜诱导草酸钙晶体形成，将能更贴近地了解草酸钙结石在尿路表皮细胞上的形成病理。
Studies on the biomineralization of calcium oxalate crystals were performed in vitro using monolayer film and Langmuir-Blodgett film as templet. SEM, ESEM, TEM, AFM, XRD and FT-IR were used to characterize calcium oxalate crystals obtained from a series of experiments.The monolayer which was composed of different materials had different effect on the formation of calcium oxalate crystals at the interface of monolayer/water. The growth of COM crystals at stearic acid monolayer was regular and both end of the crystals became sharp angles because stearic acid molecular has negative group. The crystals beneath DPPC monolayers were oriented with the elongated hexagonal ( 101 )face paralleled to the plane of the monolayer and smaller than those from bulk solution.Chondroitin sulfate A (C4S), as a kind of endogenetic urinary macromolecule, not only increased the supersaturation of CaC2O4 in solution, but also inhibited the two-dimensional growth and aggregation of COM crystals.The growth of calcium oxalate crystals was influenced by surface pressure beneath DPPC monolayer film. There were some crystals which have the same appearance as COM crystals obtained from pure water system when monolayer surface pressure was hold 1,10 and 30 mN/m while those growth at 20 mN/m were perfect orderly induced by DPPC monolayer. It was also indicated that DPPC monolayer had distinctly effect on the initial nucleation of COM crystals through the examination by TEM.Under DPPC monolayer, the appearance of COM was also different when different additives were added to subphases. C4S made the elongated (101) crystal face longer and the crystals become thinner while cattle serum albumen only made COM become thinner. L-glutamic acid, one of amino residues, increased the edges and corners of COM crystals.The LB films of DPPC were also used to study the growth of calcium oxalate crystals. It was found that calcium oxalate crystals nucleated on the domain boundaries by AFM observation. The morphology of COM was also influenced by the additives of C4S and L-Glu. As increasing the concentration of C4S, the amount of COM crystals with a hexagonal prism decreased and that with a thin hexagonal slice increased. When the concentration of C4S was 0.50 mg/mL, all the calcium oxalate crystals were thin hexagonal slice COM crystals. However, as the concentration of L-Glu increased from 0.01 to 0.50 mmol/L, the hexagonal prism-like COM crystals gradually transformed to COM crystals with one or two (010) crystal face disappearance.There were some shortcomings in the present experiments as investigating the formation of urinary stone because the biologic membrane is mixed protein phospholipid monolayers and the system in which urinary stone formed in vivo is fluid. If the mixed films were used to study the formation of calcium oxalate crystals in fluid subphase, we can further understand the mechanisms of the formation of calculus crystallite at the cellular surface of urinary tract.
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