(458c) Diffusing Probes of Ca2+ Dependent Homophilic Cadherin Interactions within Microfluidic Colloidal Crystals

We report video miscopy measurements and inverse simulation analyses of specific Ca2+ dependent N-cadherins interactions between supported lipid bilayer coated silica colloids in colloidal crystalline configurations. Our results include characterization of the bilayer formation and fluidity as well as the attachment and orientation of active extracellular cadherin fragments on bilayers. Direct measurements of interaction potentials show non-specific macromolecular repulsion between cadherin fragments in the absence of Ca2+ and irreversible fusion of bilayers via cadherin mediated interactions at >1mM Ca2+. Analysis of Ca2+ dependent N-cadherin bond formation in quasi-2D colloidal crystals using inverse Monte Carlo and Brownian Dynamic simulations show significant attraction at Ca2+ concentrations significantly below previously reported values.