Semiconductor nanocrystals, known as quantum dots, have received significant attention as novel fluorescent dyes in biological field due to their unique optical characteristics. Cadmium chalcogenide quantum dots such as CdS, CdSe or CdTe are widely used for biolabelling. The major route to produce high quality quantum dots is organometallic synthesis using hydrophobic stabilizing ligand, trioctyl phosphine oxide (TOPO), at high temperature. However, since quantum dots should be water-soluble and biocompatible for biological applications, an additional reaction for ligand exchange with hydrophilic ligands like thiols is accompanied. Another way to obtain water-soluble quantum dots is to directly synthesize using hydrophilic ligands in aqueous solution. Although monothiols such as cysteine or glutathione are one of the most popular stabilizing agents, they often fail to stabilize quantum dots. Enhanced stability has been achieved by using other dithiol ligands, dihydrolipoic acid, suggesting that phytochelatins, multithiol peptides, can be a better stabilizer. Our strategy for making semiconductor nanocrystals is to construct a metabolically engineered E. coli synthesizing the cysteine-rich peptides, phytochelatins. In-vitro synthesis using cell extract will be explored for phytochelatin-directed synthesis of cadmium chalcogenide quantum dots.