We introduce a microfluidic approach to generating monodisperse, stable nanoparticle-shelled bubbles using air-in-oil-in-water (A/O/W) compound bubbles as templates. The oil phase of the A/O/W compound bubbles comprises a volatile organic solvent and a hydrophobic silica nanoparticle. Upon evaporation of the organic solvent, the nanoparticles in the oil layer form a stiff shell at the air-water interface, which drastically enhances the stability of the bubbles against dissolution and coarsening. On the basis of this approach, we demonstrate that it is also possible to generate functional bubbles stabilized by composite shells that are composed of mixtures of hydrophobic materials and nanoparticles with unique properties.

Drug eluting stents are associated with late stent thrombosis (LST), delayed healing and prolonged exposure of stent struts to blood flow. Using macroscale disturbed and undisturbed fluid flow waveforms, we numerically and experimentally determined the effects of microscale model strut geometries upon the generation of prothrombotic conditions that are mediated by flow perturbations. Rectangular cross-sectional stent strut geometries of varying heights and corresponding streamlined versions were studied in the presence of disturbed and undisturbed bulk fluid flow. Numerical simulations and particle flow visualization experiments demonstrated that the interaction of bulk fluid flow and stent struts regulated the generation, size and dynamics of the peristrut flow recirculation zones. In the absence of endothelial cells, deposition of thrombin-generated fibrin occurred primarily in the recirculation zones. When endothelium was present, peristrut expression of anticoagulant thrombomodulin (TM) was dependent on strut height and geometry. Thinner and streamlined strut geometries reduced peristrut flow recirculation zones decreasing prothrombotic fibrin deposition and increasing endothelial anticoagulant TM expression. The studies define physical and functional consequences of macro-and microscale variables that relate to thrombogenicity associated with the most current stent designs, and particularly to LST.