From 2011.igem.org

Abstract

We are using synthetic biology to build an eco-friendly system for making biologically produced quantum dots (QDs). While QDs can be manufactured through chemical processes, these processes are toxic, energy intensive, and yield dots that are challenging to use for promising biological applications. Furthermore, QDs created in this way are also thought to be more compatible with biological systems and require less energy to produce (Mi et. al.). The addition of QD manufacturing to the toolbox of synthetic biology can expand the horizons of existing isolated systems; for example, motility control and light responsiveness ( might couple with dot production to generate self assembling circuits.

In order to achieve this, our team’s primary goal was to engineer E. coli bacteria to express several different peptides which bind to and nucleate salts of heavy metals, thereby crystallizing them into QDs.

In addition, we have designed a novel sensor/feedback device in order to enable the production of QDs with more uniform emission wavelengths. Since the size of QDs is directly related to their light emission spectrum, the goal is to have E. coli produced QDs, while growing in the presence of long wave UV light, activate a light-sensitive promoter that is sensitive to the the emission spectrum of the required QD size. This promoter is coupled to the expression of an antibiotic resistance cassette. As an initial proof-of-principal, our device uses a gene encoding for chloramphenicol antibiotic resistance, placed under the control of a blue light sensitive promoter, which had been previously characterized by the 2009 iGEM team of K.U. Leuven. (https://2009.igem.org/Team:KULeuven/Design/Blue_Light_Receptor). Thus, blue QD producing E. coli would stimulate the blue light promoter resulting in antibiotic resistance, allowing the survival of only the cells producing the desired wavelength of light.