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Lecture Alexander Gaiduk


16 November 2010 FWN-Building 5114.0004, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Alexander Gaiduk
Affiliation: University of Leiden, The Netherlands
Title: Single molecules bring isnight into the nanoworld
Date: Tue Nov 16, 2010
Start: 11.00
Location: FWN-Building 5114.0004
Host: A. van Oijen
Telephone: +31 50 363 9883


Since about three decades it is possible to use single-molecule optical and mechanical detection for studies on a nanometer scale. They deliver understanding of how complex system work and reveal heterogeneities not accessible in ensemble measurements. For example, simultaneous optical detection and manipulations of a single DNA molecule by means of an atomic-force microscope allows study of the attachment of fluorescent dyes to DNA as a function of mechanical conformation of macromolecule. So far, optical detection of single molecules at room temperature has relied on fluorescent properties of labels. However, only a very small fraction of all light-absorbing molecules (chromophores) are strongly fluorescent (fluorophores). Thus, monitoring optical absorption at a single-molecule level would have definite advantages. Photothermal (absorption) microscopy provides a background-free method to detect the absorption of photostable nanoabsorbers by sensing the heat they release. A molecule in the excited state can emit light or non-radiatively relax to the ground state and dissipate heat into environment. We recently demonstrated that the absorption of a single non-fluorescent molecule can be detected at room temperature by photothermal microscopy. Further interesting candidates are natural absorbers, which would be useful for label-free optical microscopy. Moreover, photothermal microscopy provides control over the local heating of photostable labels and can easily be implemented into conventional microscopy. That makes it desirable in applications where durable labels and multidimensional detection are beneficial: such as high-throughput molecular and cell sorting, biosensing, tracking and imaging in live cells.
Last modified:22 October 2012 2.30 p.m.