Synthesis and functionalization of non-toxic visible-emitting nanocrystals

We have studied phosphor doping of core / shell nanocrystals (NCs) where the impurity emitter resides in the shell. We have found that a two step synthesis can be used to create these non-toxic materials that efficiently transfer energy from the core to the doped shell. These core / shell NCs retain ample brightness when solubilized in water. We explored the functionalization of these materials in water as well to create ratiometric chemical sensing agents. First, we used a method of controlled polymerization to synthesize amphiphilic polymers to solubilize the intrinsically hydrophobic NCs into water. The polymer has a build in "chemical handle" which we use to functionalize the polymers closely bound to the NC with a fluorescent dye in aqueous solution. We have found that there exists efficient Forster resonant energy transfer from the shell doped phosphors to the surface bound dyes. Conjugation of the NC to an environmentally sensitive dye such as fluorescein has also demonstrated that non-toxic doped NCs can be used to develop ratiometric sensing / biological imaging agents. Last, we have found that the same technique can be applied to functionalize non-emissive magnetic nanocrystals as well.