Project inspiration: Quantum Dots
What shines the world?
Quantum dots (QDs) are tiny semiconductor particles. Commercially, QDs have a wide variety of applications, such as bioimaging and heavy metal detection.
However, the process of chemical synthesis of QDs will produce extremely toxic waste water, which will harm the environment. In order to synthesize in a more environmentally friendly way, we’re trying to improve the biosynthesis of QDs.
And let’s welcome the bacteria team, Biosquad!
Simple Understanding: Quantum dots nowadays
Quantum dots (QDs) are tiny semiconductor particles a few nanometers in size. There are many kinds of QDs. Among these, CdS quantum dots have the widest applications and can be fast synthesized. QDs have the properties of controllable photoluminescence due to the effect of dimensional quantization . Therefore, when light shine on them, they will present different colors according to their size[Figure 1].
The multicolor property of QDs offer opportunities for detecting multiple targets simultaneously. Applications of quantum dots for in vitro and in vivo bioimaging, targeting, and drug delivery have been widely discussed recent years. Due to the unique surface chemistry and binding affinity, QDs have facilitated the development of sensitive sensors over the past decade. One of the most important QDs sensing application is heavy metal detection in environment. On top of these, QDs are important industrial material from TV displays to nanocomposites. Actually, quantum dots are now indispensable in technology and our daily life[Figure 2].
Defining the problem: Toxic Chemical Synthesis
The preparation of CdS quantum dots includes: sol-gel Method, photochemical method, and solvothermal method. All the methods above require enormous solvents and need to be prepared in the high pressure and high-temperature environment and with only nitrogen. Temperature can rise up to 200°C and solvent such as thioacetamide and polyvinylpyrrolidone are toxic or potential cancer causing agents[5-12]. These factors are crucial for the exchange of ligands however result in a serious waste of energy and pollution. Especially photochemical preparation of quantum dots needing Co60 as resources that can not only cause radiation contamination but also end up endangering people’s health.
Our solution: BioSquad-Biothesis of CdS via E. Coli
Since ancient times, there’s been some microbial lived in the environment with heavy metals, such as cadmium. In response to these toxic metals, microbials have evolved some resistance mechanisms. These responses include the production of cysteine-rich peptides to trap intracellular metals and direct growth of Glutathione-metal complexes. CdS is one of the example which has QDs properties. These inspire us to pursuit biological approaches to quantum dots synthesis.
Therefore, 2020 NTHU Taiwan dedicate to improve the efficiency of E.coli biosynthesis of quantum dots to replace chemical synthesis methods. We study QDs synthesis pathway in E.coli. After that, we clone genes in E.coli which will improve the synthesis process. We also perform modeling to look into the mechanisms of E.coli synthesizing QDs. In order to monitor formation of QDs during our experiments, we construct a bioreactor which can provide useful real time information. To enhance public awareness of potential pollution around us, we visit schools from elementary, high school to college. We believe education is important for reducing the pollution and promote the future of biosynthesis quantum dots.
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