In the cases where CSSNCs are used in biological medium , the core is a quantum dot .
The shell can be an organic molecule or biological ligands , such as a DNA , that are used for biocompatibility and targeting .
In the cases where CSSNCs are used in biological medium , the core is a quantum dot and the shell can be an organic molecule or biological ligands , such as a DNA , that are used for biocompatibility and targeting .