CdSe/ZnS quantum dot-Cytochrome c bioconjugates for selective intracellular O2˙⁻ sensing.

We demonstrate that the coupling system of negatively capped CdSe/ZnS QDs with an oxidized Cytochrome c (Cyt c) is capable of the fluorescent imaging of a superoxide radical (O(2)˙⁻) with high sensitivity and specificity in living cells, without interference from other Reactive Oxygen Species (ROS) or relevant intracellular components.