ABSTRACT
We introduce a general methodology based on magnetic colloids to study the recognition kinetics of tethered biomolecules. Access to the full kinetics of the reaction is provided by an explicit measure of the time evolution of the reactant densities. Binding between a single ligand and its complementary receptor is here limited by the colloidal rotational diffusion. It occurs within a binding distance that can be extracted by a reaction-diffusion theory that properly accounts for the rotational Brownian dynamics. Our reaction geometry allows us to probe a large diversity of bioadhesive molecules and tethers, thus providing a quantitative guidance for designing more efficient reactive biomimetic surfaces, as required for diagnostic, therapeutic, and tissue engineering techniques.
Subject(s)
Colloids/chemistry , Magnetics , Receptors, Cell Surface/analysis , Biotin/chemistry , Kinetics , Serum Albumin, Bovine/chemistry , Streptavidin/chemistryABSTRACT
We develop a micropipette rheometer to study the effect of oscillatory shear flow on the spontaneous fluctuations of phospholipid bilayers. Our results on giant vesicles show that oscillatory shear flow leads to a suppression of membrane fluctuations. They also imply that the Helfrich equation is modified in the presence of the flow. This equation, a fundamental constitutive relation between the amount of area stored in the fluctuations and the membrane tension, must be supplemented under oscillatory shear by a flow excess function that we determine.