Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Near-field scanning optical microscopy in liquid for high resolution single molecule detection on dendritic cells

(full pdf)

M. Koopman, A. Cambi, B.I. de Bakker, B. Joosten, C.G. Figdor, N.F. van Hulst, M.F. García-Parajó
FEBS letters (Federation of European Biochemical Societies)
vol 573 (2004) issues 1-3 p6 - p10 july 6 2004

Clustering of cell surface receptors into micro-domains in the plasma membrane is an important mechanism for regulating cellular functions. Unfortunately, these domains are often too small to be resolved with conventional optical microscopy. Near-field scanning optical microscopy (NSOM) is a relatively new technique that combines ultra high optical resolution, down to 70 nm, with single molecule detection sensitivity. As such, the technique holds great potential for direct visualisation of domains at the cell surface. Yet, NSOM operation under liquid conditions is far from trivial. In this contribution, we show that the performance of NSOM can be extended to measurements in liquid environments using a diving bell concept. For the first time, individual fluorescent molecules on the membrane of cells in solution are imaged with a spatial resolution of 90 nm. Furthermore, using this technique we have been able to directly visualise nanometric sized domains of the C-type lectin DC-SIGN on the membrane of dendritic cells, both in air and in liquid.
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