Theoretical study of fluorescence resonant energy transfer dynamics in individual semiconductor nanocrystal–DNA–dye conjugates

Motivated by recent experimental studies of fluorescence resonant energy transfer (FRET), we consider the influence of the temperature-dependent microscopic spectral overlap and relative orientation of the transition dipoles of fluorophores on the nanosecond dynamics of photon statistics and energy transfer efficiency in semiconductor nanocrystal–DNA–organic dye conjugates using Monte-Carlo simulations. Our calculated mean energy transfer efficiencies are found to be well consistent with those measured in experiment at low temperatures. For the higher temperatures, our results demonstrate that the use of Förster radius estimated from the isotropic dynamic average value of 2/3 for the orientation parameter term may lead to overestimation of energy transfer efficiency for the cases of the rigid arrangement of fluorophore transition moments, and thereby deteriorate the precision of the analysis of donor–acceptor distances. Our theoretical results here underline the importance of a detailed understanding of the microscopic picture of FRET for exploiting this spectroscopic technique in various nano- and bio-applications.