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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
FRET and Translocation in Cell-based Imaging
Dec. 14, 2009

FRET and Translocation in Cell-based Imaging

Microscopy in combination with fluorescence labeling techniques has enabled us to look at diverse biological processes. By tagging a protein of interest, we learn about its intracellular localization and dynamics. Fluorescence resonance energy transfer (FRET) sensors, which carry two fluorescent tags instead of one, a donor and an acceptor, are generated to obtain information about protein function. While the use of multiple labels is straightforward and common in high content imaging and screening, the use of multiple FRET sensors is more difficult. more
Dec. 14, 2009

Holographic Optical Tweezers

The actin cortex, a quasi two-dimensional network of actin, plays an important role in cell stability, motility and viscoelasticity. In vivo, its characteristic properties are controlled by various actinbinding proteins (ABPs), such as crosslinkers or ions. To investigate the influence of specific crosslinkers on the network's behaviour exclusively, we create and probe biomimetic models of the actin cortex. This is realized using microbeads trapped by holographic optical tweezers (HOTs) as scaffold for the actin filaments. more
Bioactive Surfaces Based on PEG Brushes
Dec. 07, 2009

Bioactive Surfaces Based on PEG Brushes

The control over cell-surface interactions is a highly important issue for biomedical and biotechnology applications. Novel thermoresponsive PEG (Poly(ethylene glycol) surface coatings allow convenient control over the cell adhesion and do not interfere with membrane proteins. Here we benchmark the ability of the surfaces to control cell adhesion and quantify the interfacial interactions via colloidal probe atomic force microscopy (AFM). more
Making Light Sound
Nov. 30, 2009

Making Light Sound

Optical interrogation of biological tissues offers great variety of intrinsic probing mechanisms as well as highly specific contrast approaches based on tissue-specific expression of fluorescent proteins and extrinsically administered molecular biomarkers. Yet, most of the important living organisms and tissues remain inaccessible by the current optical imaging techniques due to complications arising from intense light scattering in tissues. more
Open your Eyes: Mites Spin a Line
Nov. 16, 2009

Open your Eyes: Mites Spin a Line

Tetranychus urticae is a phytophagous mite living in group. Every individual produces silk strands and constructs a common web for the colony. In spite of the silk value for T. urticae survival, silk remains poorly studied. We developed a technique to dye the silk on both inert and living substrates. Fluorescent brightener 28 was used to visualize the silk. This technique will help to carry out future studies about the web architecture of T. urticae and other silk-spinning arthropods. Introduction more
Quantitative Electrical Nanometrology
Nov. 09, 2009

Quantitative Electrical Nanometrology

In this paper state of the art electrical nanometrology techniques are reviewed with the focus on semiconducting materials. The basics of scanning capacitance microscopy, scanning spreading resistance microscopy, scanning microwave microscopy, and Kelvin probe force microscopy, and their applicability on various material systems are discussed. Quantitative Kelvin probe force microscopy measurements on semiconductors, namely on a conventional dynamic random-access memory cell and on a cross-sectionally prepared Si epilayer structure, are presented. more
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