脂质体中超快质子转移的盐效应。

Salt effect on the ultrafast proton transfer in niosome.

机构信息

Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.

出版信息

J Phys Chem B. 2012 Jul 19;116(28):8105-12. doi: 10.1021/jp3043957. Epub 2012 Jul 10.

Abstract

Excited state proton transfer (ESPT) of pyranine (8-hydroxypyranine-1,3,6-trisulfonate, HPTS) in a niosome is studied by fluorescence correlation spectroscopy (FCS) and femtosecond up-conversion. The niosome consists of a neutral surfactant triton X-100 (TX-100) and cholesterol. FCS studies suggest that in the presence of niosome almost all of the HPTS is transferred to the niosome and the amount of free HPTS present in bulk water is negligible. The time constant of initial proton transfer (τ(PT)) in niosome (40 ps) is ∼8 times slower than that (5 ps) in bulk water, while the time constants of recombination (τ(rec)) and dissociation (τ(diss)) are ∼4 times and ∼1.5 times slower in niosome, respectively. On addition of NaCl, the rate of ESPT is markedly retarded both in free water and in niosome. In the niosome, τ(PT) slows down to 80 ps in 1 M NaCl and 225 ps in 4 M NaCl.

摘要

通过荧光相关光谱（FCS）和飞秒上转换研究了尼罗红（8-羟基-1,3,6-三磺酸吡啶，HPTS）在脂质体中的激发态质子转移（ESPT）。脂质体由中性表面活性剂 Triton X-100（TX-100）和胆固醇组成。FCS 研究表明，在脂质体存在的情况下，几乎所有的 HPTS 都转移到了脂质体中，而在大量水中存在的游离 HPTS 的量可以忽略不计。脂质体中初始质子转移（τ（PT））的时间常数（40 ps）比在大量水中的时间常数（5 ps）慢约 8 倍，而重组（τ（rec））和离解（τ（diss））的时间常数分别慢约 4 倍和 1.5 倍。加入 NaCl 后，游离水和脂质体中的 ESPT 速率明显减慢。在脂质体中，τ（PT）在 1 M NaCl 中减慢到 80 ps，在 4 M NaCl 中减慢到 225 ps。