In a world where energy is becoming increasing expensive, it it tempting to think of quantum dots as merely a way to get a flashlight or imaging light source with low energy drain. However, this phenomena has current applications in epigenetics and possible future physical realizations of quantum computing and theoretical condensed matter applications. Silencing certain genes and observing the consequences is one experimental method use to explore the genome. This is one way quantum dots are used.
Genes can be silenced indirectly by blocking messenger RNA. This can be done by introducing "small interfering RNA" (SiRNA). Quantum dots are a highly effect method of delivering the siRNA. Each quantum dot was surrounded by a proton sponge that carried a positive charge. Without any quantum dots attached, the siRNA's negative charge would prevent it from penetrating a cell's wall. With the quantum-dot chaperone, the more weakly charged siRNA complex crosses the cellular wall, escapes from the endosome (a fatty bubble that surrounds incoming material) and accumulates in the cellular fluid, where it can do its work disrupting protein manufacture.
The technique is described in "Proton-Sponge Coated Quantum Dots for siRNA Delivery and Intracellular Imaging" by Maksym V. Yezhelyev, Lifeng Qi, Ruth M. O’Regan, Shuming Nie, and Xiaohu Gao.