Fri, 08 Aug 2008 01:36:44 BST CiteULike: di dchen Kremer http://www.citeulike.org/user/dchen/author/Kremer CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/1719295 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 3. (2007)</i><br /><br />Forces between single pairs of negatively charged micrometer-sized colloids in aqueous solutions of monovalent, divalent, or trivalent counter-ions at varying concentrations have been measured by employing optical tweezers. The experimental data have been analyzed by using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and a numerical solution of the Poisson-Boltzmann (PB) equation. With monovalent counterions, the data are well described by the DLVO and PB theories, suggesting that the DLVO theory is adequate to describe the colloidal forces at these conditions. At higher counter-ion valence, the approximations within the two theories become evident. Forces between single pairs of charged colloids in aqueous salt solutions C Gutsche UF Keyser K Kegler F Kremer P Linse doi:10.1103/PhysRevE.76.031403 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 3. (2007) 2007-10-02T11:29:36-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 76 3 APS 2007 charge colloids cool opticaltweezer pre technique http://www.citeulike.org/user/dchen/article/2767397 <i>Physical Review Letters, Vol. 100, No. 11. (2008)</i><br /><br />Optical tweezers are employed to measure the forces of interaction within a single pair of DNA-grafted colloids, dependent on the molecular weight of the DNA chains, and the concentration and valence of the surrounding ionic medium. The resulting forces are short range and set in as the surface-to-surface distance between the colloidal cores reaches the value of the brush height. The measured force-distance relation is analyzed by means of a theoretical treatment that quantitatively describes the effects of compression of the chains on the surface of the opposite-lying colloid. Quantitative agreement with the experiment is obtained for all parameter combinations. Polyelectrolyte-Compression Forces between Spherical DNA Brushes Kati Kegler Martin Konieczny Gustavo Espinosa Christof Gutsche Matthias Salomo Friedrich Kremer Christos Likos doi:10.1103/PhysRevLett.100.118302 Physical Review Letters, Vol. 100, No. 11. (2008) 2008-05-07T21:14:58-00:00 2008 Physical Review Letters 100 11 APS biology colloids interaction opticaltweezer http://www.citeulike.org/user/dchen/article/2563086 <i>Physical Review Letters, Vol. 98, No. 5. (2007)</i><br /><br />Optical tweezers are employed to measure the forces of interaction between single DNA-grafted colloids. Parameters to be varied are the length of the DNA, the grafting density, and the ion concentration of the surrounding medium. From the measured force-separation dependence an interaction length at a given force is deduced. It shows in the mushroom regime a scaling with the grafting density which levels off for brushes. For the latter the transition from an osmotic to a salted brush can be traced in detail by varying the ion concentration in accordance with mean field theories. Forces of Interaction between DNA-Grafted Colloids: An Optical Tweezer Measurement K Kegler M Salomo F Kremer doi:10.1103/PhysRevLett.98.058304 Physical Review Letters, Vol. 98, No. 5. (2007) 2008-03-19T16:59:43-00:00 2007 Physical Review Letters 98 5 APS 2007 biology colloids opticaltweezer