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Optical Tweezers - SINGLE
MOLECULE BIOSENSOR & MANIPULATION
Contact: Dr. Andy Sischka |
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Micron-sized objects like beads, colloids
or cells can be trapped, steered and manipulated by light and
allow force experiments on a single molecule level at a sensitivity
level of 0.1 pN. We set up two high stability single-beam optical
tweezers (OT) system on an inverted light microscope which allows
quantitative and analytical experiments with single molecules
or cells in an experimental force range of 0.1-900 pN. |
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Images: OT scheme, single molecule biosensor,
single cell probing with functionalized bead |
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Project 1 |
Mechanical Single Molecule Biosensor |
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Based on our optical tweezer setup we established
a single DNA biosensor, where a single lambda-DNA molecule is
manipulated between two polystyrene beads and allows real-time
monitoring of intramolecular forces in very fast one-shot experiments.
Upon (specific and unspecific ) binding of small ligands to
DNA (major groove binding, minor groove binding, intercalation,
…) the elastic force response of the probed DNA molecule
immediately changes and allows real-time biosensoric monitoring
and an identification of the corresponding binding motif (force
fingerprint). This biosensor instrument is currently evaluated
for rapid (physicochemical) screening of possible anti-cancer
therapeutics. |
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Publications: [see section "Publications"] |
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Collaborations: N. Sewald, Dept. of Bioorganic
Chemistry, Bielefeld University; H. Ihmels, Dept. of Org. Chemistry,
Siegen University |
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Project 2 |
Single Cell Receptor Probing |
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Detection and quantification of single, specific
interaction forces between a membrane bound receptor on a living
B-cell (BCR) with OT was achieved. Specific anti BCR antibodies
immobilized on a micron-sized polystyrene bead which was steered
in our optical trap proved that functional probing of individual
membrane proteins on single living cells is possible and opens
new, fascinating possibilities for future single cell experiments
like the investigation of dynamic aggregation of membrane receptor
to functional multimers. |
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Publications: [see section "Publications"] |
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Collaboration: J. Wienands, Dept. of Biochemistry,
Göttingen University |
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Project 3 |
Nanoscreening of Topoisomerase Inhibition
by Lamellarin D |
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We applied single molecule techniques like
atomic force microscopy (AFM) and optical tweezers (OT) in order
to identify and investigate the biophysical mechanisms that
might help to develop a topoisomerase inhibition nanoscreening.
From the active anti-cancer chemotherapy research lines, topoisomerases
stand in a high relevant topic of interest due to the specificity
properties of the Topo-DNA complex. DNA handling enzymes such
as topoisomerases represent a promising and direct effector
against tumour proliferation, and a selective weapon against
uncontrolled cellular growth. Topoisomerases, as several biologically
important macromolecules, undergo mechanical motions that are
essential to their function. Therefore, robust, powerfull and
highly sensitive biophysical applications are needed for micromanipulation
techniques with high resolution at the single-molecule level.
Understanding the mechanism of action of the enzyme in the presence
of its inhibitors is a major requirement for future clinical
development of important therapeutic agents. |
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Publications: [see section "Publications"] |
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Collaborations: D. Pla, M. Alvarez, F. Albericio,
and X. Fernandez-Busquets, Barcelona University |
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other ongoing projects [...] |
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We acknowledge funding from DFG within
SFB 613 (Germany) |
