Radial Profile of Counterion Concentration of a Single Polyelectrolyte
文献类型：期刊论文
| 作者 | Luo, Shuang-jiang; Gao, Pei-yuan; Guo, Hong-xia; Yang, Jing-fa; Zhao, Jiang |
| 刊名 | ACTA POLYMERICA SINICA
 |
| 出版日期 | 2017-09-20 |
| 期号 | 9页码:1479-1487 |
| 关键词 | Polyelectrolyte Counterions Single Molecule Fluorescence |
| 英文摘要 | The distribution of counterions around the charged chain of polyelectrolyte is the key aspect of its physical and chemical properties. In the current study, the spatial profile of counterion concentration along the radial direction of the molecular chain of sodium polystyrene sulfonate (NaPSS) is investigated by single molecule fluorescence technique, fluorescence correlation spectroscopy (FCS) and photon counting histogram (PCH) technique. FCS measures the diffusion coefficient (therefore the hydrodynamic radius) of a single PSS- chain while PCH measures the molecular brightness of a single fluorophore attached to the chain end. By chemical reactions, a pH responsive fluorophore (Oregon Green 488, OG488) is precisely positioned at different distances to the end of PSS- chain, using hydrophilic polypeptide chains of different length as spacers. The concentration distribution of hydronium ions at the vicinity of the PSS- chain is measured by examining the molecular brightness of OG488, by numerical fitting the PCH data using super-Poisson distribution function. The results demonstrate that the concentration of hydronium in the vicinity of the PSS- chain is 2 - 3 orders of magnitude higher than that in the bulk solution (at the infinite distance to the chain), evidencing the existence of counterion cloud around the charged chain. By varying the position of the probe with the adjustment of chain length of polypeptide, the local pH value at different distances to the PSS- chain end is measured and therefore the spatial profile of counterion concentration around the direction towards away from the chain is probed. The results show that the counterion concentration decreases very sharply with the increase of the distance (within 2.0 nm) to the PSS- chain. It is further discovered that the concentration gradient decreases with the increase of the bulk pH, demonstrating the expansion of the counterion cloud as the result of the entropy effect by dilution of hydronium ions. The results clearly prove that the counterions distribution around a charged macromolecule is the result of balance of electrostatic attraction and the process of entropy maximization, i.e. the process of counterion adsorption, instead of the conventional counterion condensation. |
| 语种 | 英语 |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/39157]  |
| 专题 | 化学研究所_高分子物理与化学实验室 |
| 作者单位 | Chinese Acad Sci, Inst Chem, Beijing 100190, Peoples R China |
| 推荐引用方式 GB/T 7714 | Luo, Shuang-jiang,Gao, Pei-yuan,Guo, Hong-xia,et al. Radial Profile of Counterion Concentration of a Single Polyelectrolyte[J]. ACTA POLYMERICA SINICA,2017(9):1479-1487. |
| APA | Luo, Shuang-jiang,Gao, Pei-yuan,Guo, Hong-xia,Yang, Jing-fa,&Zhao, Jiang.(2017).Radial Profile of Counterion Concentration of a Single Polyelectrolyte.ACTA POLYMERICA SINICA(9),1479-1487. |
| MLA | Luo, Shuang-jiang,et al."Radial Profile of Counterion Concentration of a Single Polyelectrolyte".ACTA POLYMERICA SINICA .9(2017):1479-1487. |
入库方式： OAI收割
来源：化学研究所
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