Naturally occurring polyamines putrescine, cadaverine, spermidine, and spermine are analogues of the species-specific long-chain polyamines found in diatoms. Scanning electron microscopy and energy-dispersive spectroscopy show that the reactions of a soluble Ti(IV) precursor with spermidine and spermine, but not putrescine or cadaverine, produce nanostructured irregular polyhedra of titanium oxide. At 25 degrees C, the average size of the particles formed with spermidine is 400 +/- 150 nm, and with spermine, 140 +/- 50 nm. Although the particles are X-ray amorphous at room temperature, annealing studies reveal that the particles adopt crystallinity at higher temperatures characteristic of anatase (TiO2). The major portion of the biopolyamines is not coprecipitated with the solid but is left in solution. Kinetic measurements reveal an initial fast step followed by two slower phases of reaction. At 25 degrees C, k(1obs) and k(2obs) for the reaction with spermidine are 5 x 10(-3) s(-1) and 3.6 x 10(-4) s(-1), respectively, and for spermine, 4.8 x 10(-3) s(-1) and 4.2 x 10(-4) s(-1), respectively. Taken together, the data suggest spermidine and spermine are biocatalysts for the precipitation of nanostructured titanium oxide.

译文

天然存在的多胺腐胺,尸胺,亚精胺和精胺是硅藻中特定物种的长链多胺的类似物。扫描电子显微镜和能量色散光谱表明,可溶性Ti(IV)前体与亚精胺和亚精胺的反应,而不是腐胺或尸胺的反应,生成纳米结构的不规则二氧化钛。在25℃下,由亚精胺形成的颗粒的平均尺寸为400±150nm,与亚精胺形成的颗粒的平均尺寸为140±50nm。尽管颗粒在室温下是X射线无定形的,但退火研究表明,颗粒在较高温度下具有锐钛矿(TiO2)的特征结晶性。生物多胺的大部分不与固体共沉淀,而是留在溶液中。动力学测量揭示了最初的快速步骤,随后是两个较慢的反应阶段。在25摄氏度下,与亚精胺反应的k(1obs)和k(2obs)分别为5 x 10(-3)s(-1)和3.6 x 10(-4)s(-1),对于精胺分别为4.8 x 10(-3)s(-1)和4.2 x 10(-4)s(-1)。两者合计,数据表明亚精胺和亚精胺是用于沉淀纳米结构二氧化钛的生物催化剂。

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