Kathleen T. Krist and William G. Noid Department of Chemistry, Pennsylvania State University
MRSEC researchers have developed a theory for molecular chemotaxis, active motion up or down a gradient in chemical concentration, driven by specific non-covalent interactions between molecules. The free energy released due to binding between a probe P and a ligand L generates a force that drives the two species towards each other. The magnitude of the chemotactic shift μP depends on the binding strength and the diffusivity of the probe-ligand complex. Insights from this theory can guide development of chemotaxis-based devices that sort and separate fluids components actively and against diffusional gradients.