Simultaneous analysis of labeled and unlabeled protein molecules (or microspheres) with inverse-fluorescence correlation spectroscopy

by Stefan Wennmalm (KTH, Applied Physics)

Thursday 31 Mar 2011, 09:15 → 10:00 Europe/Stockholm

FB42

In analysis of biomolecules or particles, in solution and in cells, several methods exist for estimating biomolecule/particle size, or interactions between biomolecules or particles. The established methods can analyze either unlabeled particles, for example dynamic light scattering, or labeled particles, for example Fluorescence Correlation Spectroscopy, but cannot simultaneously analyze labeled and unlabeled biomolecules/particles. Inverse-Fluorescence Correlation Spectroscopy, iFCS, overcomes this limitation by detecting a signal from the environment that surrounds the biomolecules of interest, which enables unlabeled detection. In combination with simultaneous detection of the labeled particles in a second detection channel, this allows eg the fraction of labeled particles to be determined. Moreover, iFCS provides the first direct measurement of the volume of particles and even protein molecules in solution, from the amount of displaced solution, in line with Archimedes’ principle.