• Fluorescence resonance energy transfer (FRET) in chemistry and biology: Non-Förster distance dependence of the FRET rate

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    • Keywords

       

      Fluorescence resonance energy transfer (FRET); non-Förster regime; single molecule spectroscopy; donor-acceptor system

    • Abstract

       

      Fluorescence resonance energy transfer (FRET) is a popular tool to study equilibrium and dynamical properties of polymers and biopolymers in condensed phases and is now widely used in conjunction with single molecule spectroscopy. In the data analysis, one usually employs the Förster expression which predicts (l/R6) distance dependence of the energy transfer rate. However, critical analysis shows that this expression can be of rather limited validity in many cases. We demonstrate this by explicitly considering a donor-acceptor system, polyfluorene (PF6)-tetraphenylporphyrin (TPP), where the size of both donor and acceptor is comparable to the distance separating them. In such cases, one may expect much weaker distance (as l/R2 or even weaker) dependence. We have also considered the case of energy transfer from a dye to a nanoparticle. Here we find l/R4 distance dependence at large separations, completely different from Förster. We also discuss recent application of FRET to study polymer conformational dynamics.

    • Author Affiliations

       

      Sangeeta Saini1 Harjinder Singh1 2 Biman Bagchi1

      1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore - 560 012
      2. Department of Chemistry, Panjab University, Chandigarh - 160 014
    • Dates

       
  • Journal of Chemical Sciences | News

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