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Updated: May 21, 2026

Single Liposome Measurements for the Study of Proton-Pumping Membrane Enzymes Using Electrochemistry and Fluorescent Microscopy
Published on: February 21, 2019
Salt effect on the ultrafast proton transfer in niosome
Tridib Mondal1, Shirsendu Ghosh, Atanu Kumar Das
1Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
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.
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