单链收缩和再扩张的聚苯乙烯磺酸盐：在单分子水平上对其再进入冷凝的研究。

Single chain contraction and re-expansion of polystyrene sulfonate: a study on its re-entrant condensation at single molecular level.

机构信息

Beijing National Laboratory of Molecular Science, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.

出版信息

J Chem Phys. 2009 Dec 21;131(23):231103. doi: 10.1063/1.3276278.

DOI:10.1063/1.3276278

PMID:20025307

Abstract

Single chain conformation of a polyelectrolyte (polystyrene sulfonate, PSS(-)Na(+)) during its re-entrant condensation was studied by fluorescence correlation spectroscopy (FCS) with single molecule sensitivity. The contraction and re-expansion of PSS(-)Na(+) chain were observed with the addition of counterions of different valencies. The formation of aggregation and precipitation of PSS(-)Na(+) and its redissolution were observed in accordance with the chain contraction and re-expansion process for the PSS(-)Na(+) chain upon the addition of trivalent La(3+) ion. Chain contraction and re-expansion of the PSS(-)Na(+) chain were also observed with the addition of monovalent Cs(+) and divalent Ca(2+) ions, under which condition, the re-entrant condensation was not observed. The results demonstrate that the high sensitivity of FCS can really study single PSS(-)Na(+) chain under extremely dilute situation.

摘要

通过具有单分子灵敏度的荧光相关光谱（FCS）研究了聚电解质（聚苯乙烯磺酸钠，PSS（-）Na（+））在再进入凝聚过程中的单链构象。随着添加不同价态的抗衡离子，观察到 PSS（-）Na（+）链的收缩和再扩展。随着三价 La（3+）离子的加入，观察到 PSS（-）Na（+）的聚集和沉淀的形成以及其再溶解，这与 PSS（-）Na（+）链的链收缩和再扩展过程一致。在添加单价 Cs（+）和二价 Ca（2+）离子的情况下，也观察到 PSS（-）Na（+）链的收缩和再扩展，在这种情况下，未观察到再进入凝聚。结果表明，FCS 的高灵敏度确实可以在极其稀有的情况下研究单个 PSS（-）Na（+）链。