"Hyper-bright" near-infrared emitting fluorescent organic nanoparticles for single particle tracking.

or non luminescent [ 2 ] nano-objects and can allow single particle tracking (SPT) the motion of biomolecules both for in vivo and in vitro applications. Ideally, optical probes should be bright, stable in physiological and cellular environments, have large photostability with low toxicity and good biocompatibility (i.e., do not disturb or destroy healthy cells). Small aromatic organic fl uorophores [ 3 ] and autofl uorescent proteins have been the earliest single molecule fl uorescent probes used in living cells. [ 4 ]