Millisecond curing time of a molecular adhesive causes velocity-dependent cargo-loading of molecular shuttles

It has been recently discovered that biological systems exploit complex intermolecular bonds, such as the "catch bond" between FimH proteins and mannose, to regulate dynamic assembly processes. Here we show that the assembly of hybrid nanostructures also has to account for and ideally exploit the subtleties of the utilized intermolecular interactions. We focus on the biotin-streptavidin bond, which gains its ultimate strength on a time scale of milliseconds, due to existence of metastable binding states. As a consequence of the gluelike character of this widely used intermolecular bond, the velocity of molecular shuttles, active nanoscale transport systems based on biomolecular motors and their associated filaments, has to be optimized to permit efficient attachment of cargo via biotin-streptavidin linkages. The attachment process can only be understood by combining rigorous mechanical engineering analysis with detailed physicochemical models.