Picosecond absorption studies of intermolecular electronic energy transfer in micellar systems. 1. Inhomogeneous spatial distribution and indirect donor-donor interaction

Abstract

indicating that the structure of the reverse micellar assembly was retained.13The systems studied here show the potential for higher ordering that chemical oscillators can display with the addition of spatially ordered features. Such a situation could have been important at some point in chemical evolution. In a more specific manner it may be envisaged that successive accretion of different types of ordering was a central process in the chemical evolution of life. We note that adding the effect of spatial organization to the hypercycle accentuates its selectivity.14 Acknowledgment. G.A.R. thanks the Centre for Cellular and Molecular Biology for the facilities to carry out this research at that laboratory.

Analysis of Vertical Fluorescence Resonance Energy Transfer from the Surface of a Small-Diameter Sphere

“…FRET has been studied for geometries ranging from acceptors extended above a small protein that incorporates donor fluorophores to transfer on large infinite sheets (Badley and Teale, 1971;Fung and Stryer, 1978;Wolber and Hudson, 1979;Sklar et al, 1980) as well as in or on detergent micelles (Sato et al, 1980;Ediger et al, 1983;Kaschke et al, 1988). This report describes the analysis of a micelle system, created by a donor extended above a micelle surface, and a varying number of acceptors incorporated into the micelle surface (Aurell Wiström et al, 1996).…”

“…Equation 5 represents the steady-state quantum yield of a single donor in a micelle with k acceptors or a homogeneous population of donors in micelles with k acceptors. To better represent the situation where the micelle population is heterogeneous with regard to the number of acceptors, a Poisson distribution may be used to describe the micelle population (Ediger et al, 1984;Kaschke et al, 1988). The Poisson distribution is given by:…”

“…The spectral overlap integral (J) was calculated for donor and acceptor pairs according to Aurell Wiström et al (1996). As the transfer efficiency is sensitive to the separation of donor and acceptor where the distances are contained in the interval 0 Յ R Յ 2R 0 , and the micelle radius is ϳ0.3R 0 , the micelle geometry needs to be taken into account (Ediger et al, 1984;Kaschke et al, 1988). An idealized model was built upon the extension of an amphipathic molecule (Fig.…”

“…As the diameter of the sphere and its surface area decreases, the distribution of acceptor chromophores across the sphere population is no longer homogeneous. Rather, a Poisson distribution describes the stoichiometry of acceptor incorporation for small proteins and micelles that bind acceptor chromophores randomly (Green, 1964;Kaschke et al, 1988). The Poisson distribution has been applied to tryptophan energy transfer in small proteins and the transfer between fluorophores on the micelle surface and in its interior (Green, 1964;Badley and Teale, 1971;Sato et al, 1980;Ediger et al, 1983;Kaschke et al, 1988).…”

Efficient energy transfer between amphiphilic dendrimers with oligo(p‐phenylenevinylene) core branches and oligo(ethylene oxide) termini in micelles

“…FRET in various confined geometries, such as micelles, vesicles, clays, and zeolite, are specifically interesting 4–7. This is because these systems can provide a high local concentration of chromophores and enhanced spatial proximity between donor and acceptor molecules associated with their well‐organized structures to efficiently facilitate energy transfer 8–12. In particular, FRET in micelles has been widely investigated due not only to their biological significance associated with the similarity between the micelles and biological membranes but also to the possible use of FRET as probes for micelle/membrane studies and biomedical imaging.…”