31 March 2011

Living cells in multi-D

Fluorescence microscopy is an import tool for studying biological specimen. Multi-dimensionality, thereby, can open up new interesting perspectives. In a review article, a team of scientists from Germany under the lead of Herbert Schnekenburger give an overview on fluorescence microscopy with high spatial, spectral and temporal resolution and discuss their applicability to living cells. All methods reported are adapted to low dose of illumination, which is regarded as a key parameter to maintain cell viability. Novel designs and avoidance of extrinsic fluorescent markers also play an increasing role. In addition to single cells or cell monolayers, 3-dimensional cell cultures are of increasing importance, since they are more similar to tissue morphology and function. Applications discussed include cancer diagnosis and cell tomography under different physiological conditions.

Spatial resolution is a key parameter in optical microscopy. While light diffraction commonly limits lateral as well as axial resolution, further restrictions are due to a low focal depth at high magnification. To overcome this problem, laser scanning microscopy (LSM) techniques have been developed, where information from a focal plane is selected. Conventional wide field microscopy using structured illumination is an alternative. By imaging an optical grid in various positions of a sample, an image from the focal plane can be resolved, whereas out-of-focus light is eliminated. Yet, both techniques often need high light exposure and long measuring times, thereby damaging cells. Only a few methods with lower light exposure have been reported.

In multi-dimensional microscopy spatial resolution is often combined with high spectral or temporal resolution, thus resulting in spectral imaging or fluorescence lifetime imaging microscopy (FLIM). In addition to precise localization of fluorescent probes these techniques often permit to measure intermolecular interactions with their micro-environment. Non-radiative (Förster resonance) energy transfer (FRET) from a donor to an acceptor molecule plays an important role in this context, since intermolecular distances below 10 nm can be detected reliably. Variable-angle total internal reflection fluorescence microscopy (TIRFM) permits selective measurements of cell membranes or cell-substrate topology in the nanometer scale and is also combined with spectral or time-resolved detection.

J. Biophotonics 4(3), 143-149 (2011)

http://dx.doi.org/10.1002/jbio.201000098

Round Robin Experiment

Raman spectroscopy has already proved its effectiveness in many cases for medical diagnostics such as for cancer, cardiovascular diseases and infections. However, there are no standards in the different working groups, e.g. for sample preparation, implementation of the Raman experiments, spectra pre-treatment, data evaluation, etc.In a round robin experiment, the required groundwork will take place in order to define standardised Raman measurement methods, which will be fundamental for establishing Raman spectroscopy for clinical diagnostic procedures.

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20 March 2017

Continuing the success of the previous meetings held in Sacramento, Ottawa, Jena, and Florence, the 5th conference will come to Perth, Western Australia, running over two full days, and back-to-back with the Science on the Swan medical research conference, which delegates are strongly encouraged to also attend, at discounted rates. [more]

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