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| Format: | Artículo científico |
| Language: | en |
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Academia Brasileira de Ciências
2007
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| Online Access: | https://www.redalyc.org/articulo.oa?id=32779103 |
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Table of Contents:
- New tools to study biophysical properties of single molecules and single cells Márcio S. Rocha Oscar N. Mesquita Multidisciplinaria (Ciencias Naturales y Exactas) macrophages cell motility water transport optical tweezers single molecules We present a review on two new tools to study biophysical properties of single molecules and single cells. A laserincident through a high numerical aperture microscope objective can trap small dielectric particles near the focus. Thisarrangement is named optical tweezers. This technique has the advantage to permit manipulation of a single individualobject. We use optical tweezers to measure the entropic elasticity of a single DNA molecule and its interaction withthe drug Psoralen. Optical tweezers are also used to hold a kidney cell MDCK away from the substrate to allow precisevolume measurements of this single cell during an osmotic shock. This procedure allows us to obtain informationabout membrane water permeability and regulatory volume increase. Defocusing microscopy is a recent techniqueinvented in our laboratory, which allows the observation of transparent objects, by simply defocusing the microscopein a controlled way. Our physical model of a defocused microscope shows that the image contrast observed in this caseis proportional to the defocus distance and to the curvature of the transparent object. Defocusing microscopy is veryuseful to study motility and mechanical properties of cells. We show here the application of defocusing microscopy tomeasurements of macrophage surface fluctuations and their influence on phagocytosis. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779103 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.1 Vol.79