No abstract

Enantiomerically enriched organic compounds that have been used as chiral catalysts and ligands in asymmetric synthesis possess a heteroatom(s) such as oxygen, nitrogen, sulfur, and phosphorus in addition to carbon and hydrogen atom(s). [1] To the best of our knowledge, no chiral hydrocarbon has ever been used successfully as a chiral ligand or catalyst in asymmetric synthesis. On the other hand, [6]-and compounds, cells resumed migration and proliferated to give a confluent layer, indicating the drugs were not cytotoxic over the time course of this assay.This example establishes that the dynamic substrates are compatible with experiments to modulate cell behavior in situ and in real time. Our results suggest that this method will be broadly useful in assays for screening libraries of drug candidates that have antimigratory effects, and that can block metastasis in cancer. [16] These substrates also offer immediate opportunities for mechanistic studies of cell migration including investigations of the dependence of cell migration on the density and affinity of immobilized ligands. Finally, these active surfaces can be combined with microelectrode arrays to modulate the presentation of ligands on select regions of the substrate and to even immobilize multiple ligands on the substrate.The most important feature of this method is that these substrates are defined at the molecular scale and therefore provide complete control over ligand ± receptor interactions between cell and substrate. The use of physical organic and synthetic chemistry was critical to the design and preparation of this dynamic substrate. This molecular approach is significant because it can be applied to the design of dynamic substrates having other functions, including those that selectively release immobilized ligands and that reversibly modulate the activities of ligands. [17] Most importantly, the chemical approach described here provides unprecedented control in developing tailored substrates for modulating cell behavior, and will have an impact on programs in bioorganic chemistry, cell biology, and materials science.