Polyphosphate nanoparticles are retained at the platelet granulomere after release. (A-B) Three-dimensional reconstruction of fixed spread platelets on immobilized VWF, analyzed by confocal microscopy (microscopic images were acquired at a magnification of ×630). Blue, DAPI; orange, SYTOX. (C) Scanning electron microscopy of spreading platelets. Arrows indicate spherical structures.