Optimisation of Cadmium Selenide Quantum Dot Biosynthesis in Saccharomyces Cerevisiae and the Role of Glutathione
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The biosynthesis of quantum dots has been explored as an alternative to traditional physicochemical methods; however, relatively few studies have determined optimal synthesis parameters. Saccharomyces cerevisiae sequentially treated with sodium selenite and cadmium chloride synthesized CdSe quantum dots in the cytoplasm. These nanoparticles displayed a prominent yellow fluorescence, with an emission maximum of approximately 540 nm. Investigations into the optimisation of the biosynthetic method revealed that quantum dots were produced more efficiently when stationary phase cultures were treated directly with 1 mM sodium selenite for 6 hours, followed by incubation with 3 mM cadmium chloride in fresh growth medium. Synthesis of quantum dots reached a maximum after approximately 84 hours of reaction time. The influence of glutathione to the biosynthetic mechanism was explored through the use of 1-chloro-2,4-dinitrobenzene and buthionine sulfoximine to deplete intracellular glutathione content. The synthesis of CdSe quantum dots was significantly inhibited in most cases by 1-chloro-2,4-dinitrobenzene and buthionine sulfoximine treatment, suggesting that glutathione plays an important role in the biosynthetic process, particularly following the addition of cadmium. The possible mechanism for CdSe quantum dot formation is discussed.