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Dec. 23, 2009

Determination of Physical Properties of a Single Peptide by AFM Experiments

By stretching a polymer in solution using single molecule techniques it is possible to infer about its physical properties. In particular, AFM stretching experiments allow for a full characterization of the elasto-mechanical properties of the sample under study, taking into account both statical and dynamical regimes [1]. In the presented work, single molecule AFM force spectroscopy experiments have been used to determine mechanical properties of a polymer obtained starting from the Exon 28 (Ex28) of the human elastin gene. more
Dec. 22, 2009

Multiple Facets of Neuronal Growth

A prerequisite for an understanding of the mechanisms of nerve regeneration and neuronal development is the understanding of the principles of force generation in growth cones - the mechanical and chemical sensor of a neuron. In our working group we try to approach this issue from a variety of different aspects, combining experimental and theoretical studies of actin networks, membrane fluctuations and focal adhesion sites. more
Dec. 21, 2009

Cell Adhesion on Micro-Nanostructured Surfaces

Many aspects of cellular adhesion to the surrounding, the extracellular matrix (ECM), are of great interest as they control and influence various fundamental cell actions such as motility, differentiation, proliferation and apoptosis and hence, even the function of an organism may depend on this complex and highly regulated process. more
Dec. 18, 2009

AFM Discriminates Between Cell Lines

We report for the first time the use of Atomic Force Microscopy (AFM) in discriminating between living normal human urothelial cells (HUC) and bladder tumour cells (MGH) on the basis of their ultrastructure and nanomechanical properties. AFM imaging revealed clear differences in the shapes and dimensions of MGH and HUC cells: MGH cells had the tendency to cluster and therefore they did not spread much compared to their normal counterparts. As a consequence, the dimensions of MGH cells were found to be smaller than those of normal HUCs. more
Dec. 18, 2009

Optical Tweezer Experiments

Optical trapping techniques have evolved to the point where quantitative force measurements on biological systems can be performed down into the femtonewton range. As resolution is constantly improving, the pinpointing and elimination of noise sources become increasingly important. Allan-variance analysis is ideally suited for this task; adjacent time series are recorded and the variations between observation intervals are calculated. more
Dec. 17, 2009

Gradient Optical Traps

The powerful results in the molecular and cellular domain that are currently obtained using optical tweezers are leading to an increasing interest in this biophysical tool. Once calibrated, laser traps can be used to accurately measure the forces and displacements involved in many different molecular processes. Unfortunately, standard force detection techniques are not suitable for experiments inside living cells. more
Dec. 17, 2009

Protrusion Force Measurements with the SFM on Motile Cells

A fundamental step in cell migration is the advancement of the cell's leading edge. It is generally accepted that this motion is driven by actin polymerization against the plasma membrane but this has not been directly measured. more
Dec. 16, 2009

The “Walking” Mechanism of Kinesin-1 in 3D

Kinesin-1 is a molecular motor essential for cellular function. It transports components such as membrane-bound organelles and molecular complexes around a cell by travelling along microtubule filaments, which make up part of the cytoskeleton, while hydrolysing ATP. This motion is processive, in one direction only and is known to involve both of kinesin's two heads. Although extensively studied by a variety of techniques over many years, the mechanism these single-molecule motors use for this efficient motion on the nanoscale is not fully understood. more
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