Förster resonance energy transfer-based biosensors for multiparameter ratiometric imaging of Ca2+ dynamics and caspase-3 activity in single cells

Anal Chem. 2011 Dec 15;83(24):9687-93. doi: 10.1021/ac202595g. Epub 2011 Nov 28.


As one of the principal cytoplasmic second messengers, the calcium ion (Ca(2+)) is central to a variety of intracellular signal transduction pathways. Accordingly, there is a sustained interest in methods for spatially- and temporally resolved imaging of the concentration of Ca(2+) in live cells using noninvasive methods such as genetically encoded biosensors based on Förster resonance energy transfer (FRET) between fluorescent proteins (FPs). In recent years, protein-engineering efforts have provided the research community with FRET-based Ca(2+) biosensors that are dramatically improved in terms of enhanced emission ratio change and optimized Ca(2+) affinity for various applications. We now report the development and systematic optimization of a pair of spectrally distinct FRET-based biosensors that enable the simultaneous imaging of Ca(2+) in two compartments of a single cell without substantial spectral crosstalk between emission channels. Furthermore, we demonstrate that these new biosensors can be used in conjunction with previously reported caspase-3 substrates based on the same set of FRET pairs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biosensing Techniques*
  • Calcium / metabolism*
  • Caspase 3 / metabolism*
  • Fluorescence Resonance Energy Transfer
  • HeLa Cells
  • Humans
  • Ions / chemistry
  • Signal Transduction


  • Ions
  • Caspase 3
  • Calcium