Quantum Dots

Quantum dots are semiconducting nanoscale crystals with unique optical properties. They are usually made of cadmium and selenium (CdSe). They absorb a wide spectra of electromagnetic radiation and can emit visible photons of a narrow frequency range corresponding to the size of the crystal. Smaller particles appear bluer, and larger ones appear redder. Quantum dots are also bright, stable, and resistant to photobleaching. Because of these properties, quantum dots have many interesting applications, including medical imaging and labeling, enhanced LEDs, novel solar cells, and solid state quantum computation.

Our Project

Biological synthesis of quantum dots offers dramatic opportunities for directed assembly, detoxification, and fast integration into living systems. By BioBricking quantum dots, they can be directly incorporated into biological systems. The biological production pathway also allows QDs to be manufactured in places that do not have the ability to do high-temperature chemical synthesis, and in a more environmentally-friendly manner.

We aim to create engineered E. coli bacteria capable of nucleating quantum dots by expressing specific peptide sequences. Various metal-binding peptides have been reported to form quantum dots when expressed in E. coli. Our project will be to use the RFC23 registry assembly standard to BioBrick several metal binding peptides, express them in E. coli, and characterize their ability to nucleate quantum dots in vivo using cadmium. In addition, since cadmium metals are dangerous to the environment, we will attempt to create quantum dots with other metals such as zinc. We will characterize and compare quantum dots made both chemically and biologically.

We hope to use the biologically synthesized dots in several applications, including as a feedback mechanism and solid-state laser. It is our hope that the contribution and characterization of quantum dot-forming peptides to the BioBrick library will add an exciting tool to the synthetic biology arsenal.