US Patent 7498177 - Quantum dot with tiopronin capping group

http://www.freepatentsonline.com/7498177.html

This patent teaches using tiopronin to facilitate the coupling of quantum dots (aka semiconductor nanocrystals) to biological compounds. Claim 1 reads:

1. A quantum dot comprising:

a semiconductor core to which a plurality of ligands are covalently linked,

wherein the ligands comprise a tiopronin capping group linked to a targeting group,

said targeting group directing the quantum dot to a target selected from the group consisting of tissue type, a cell type and a cellular organelle,

wherein the targeting group is selected from the group consisting of a translocation signal peptide, a mitochondrial targeting sequence, a nuclear localisation signal, a perioxisomal targeting signal and a transport protein.