Characterization of the Self-Assembly of meso-Tetra(4-sulfonatophenyl)porphyrin (H2TPPS4-) in Aqueous Solutions
Characterization of the Self-Assembly of meso-Tetra(4-sulfonatophenyl)porphyrin (H2TPPS4-) in Aqueous Solutions
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DOI：
10.1021/bm201078d
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发表时间：
2012-01-01
影响因子：
6.2
通讯作者：
Russo, Paul S.
中科院分区：
文献类型：
--
作者：
Hollingsworth, Javoris V.;Richard, Allison J.;Russo, Paul S.
使用互补分析技术的组合，研究了在磷酸盐溶液中的meso-四（4-sulfonatophenyl）卟啉（H2 TPPS 4-）的聚集作为pH、浓度、时间、离子强度和溶液制备（从新鲜制备的2 mM储备液稀释或通过直接制备μ M溶液浓度）的函数。紫外可见光谱和荧光光谱表明，交错，并排（J型）组件的形成。它们的大小和自缔合行为，确定使用分析超离心和小角X-射线散射。我们的研究结果表明，在中性和碱性溶液中的H2 TPPS 4-，卟啉二聚体和三聚体形成在微摩尔浓度和在没有NaCl筛选任何离子相互作用。在这些低浓度和pH 4下，质子化的H4 TPPS 2-物质自组装，导致形成携带25 +/-3大环的特别稳定的聚集体。在更高的浓度下，这些结构进一步组织或重组成各种长度的管状、棒状形状，这些形状通过低温和冷冻断裂透射电子显微镜成像。当从2 mM储备溶液的稀释液制备时，在加入NaCl或两者时，甚至在pH 4下以微摩尔浓度获得了100-规模的纤维状聚集体。
The aggregation of meso-tetra(4-sulfonatophenyl)porphyrin (H2TPPS4-) in phosphate solutions was investigated as a function of pH, concentration, time, ionic strength, and solution preparation (either from dilution of a freshly prepared 2 mM stock or by direct preparation of mu M solution concentrations) using a combination of complementary analytical techniques. UV-vis and fluorescence spectroscopy indicated the formation of staggered, side-by-side (J-type) assemblies. Their size and self-associative behavior were determined using analytical ultracentrifugation and small-angle X-ray scattering. Our results indicate that in neutral and basic solutions of H2TPPS4-, porphyrin dimers and trimers are formed at micromolar concentrations and in the absence of NaCl to screen any ionic interactions. At these low concentrations and pH 4, the protonated H4TPPS2- species self-assembles, leading to the formation of particularly stable aggregates bearing 25 +/- 3 macrocycles. At higher concentrations, these structures further organize or reorganize into tubular, rod-like shapes of Various lengths, which were imaged by cryogenic and freeze-fracture transmission electron microscopy. Micron-scale fibrillar aggregates were obtained even at micromolar concentrations at pH 4 when prepared from dilution of a 2 mM stock solution, upon addition of NaCl, or both.