Excluded Volume Effect in the Fluorescence Energy Transfer of Single Donor–Multiple Acceptors in Polymer

Abstract

Fluorescence resonance energy transfer (FRET) from a donor to multiple acceptors is an interesting subject. Numerous studies using theoretical models and simulations have focused on the excluded volume effect, which was not considered in Förster's first derivation. In this work, we first present the experimental results on the excluded volume effect by employing time-resolved FRET. Coumarin 334 (C334) was used as the energy donor whereas hemin and cytochrome c (cyt c) were used as the energy acceptors. The fluorescence intensity decays were measured for C334 surrounded by a number of acceptors in poly(acrylic acid). We have observed that the excluded volume effect is markedly pronounced with cyt c compared with hemin when the acceptor concentration is high (>5 mM). The results, which may be explicitly described by the relative molecular sizes of two acceptors, showed that the excluded volume effect should be considered in the interpretation of FRET data, especially when bulk chromophores are used.

Validity of Förster Theory for Vibrational Energy Transfer in Low-Dimensional Water

“…In realistic low-dimensional systems such as porous materials, cylindrical and spherical pores, and nanotubes, the geometries of molecular distribution can be more restricted, and the restricted geometries should be incorporated by appropriately generalizing the decay function in eq . In such a context, the shape and dimensionality effects in nanocrystal systems and the excluded volume effects in a polypeptide system have been analyzed for Förster resonance energy transfer kinetics. Interfacial waters near lipid membranes and surfactant monolayers can also be interesting examples of low-dimensional waters as their conformations were found to be restricted by strong hydrogen bonding to the headgroups of lipid and surfactant. − It might be interesting to learn how this strong hydrogen bonding can affect the VET dynamics among the interfacial water molecules, which the low-dimensional Förster theory may be utilized to study.…”