IGEM:American University/2009/Notebook/BCHM 2/2017/03/08

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Background Today, we will use Myoglobin (which gave us the best resolution so far) to analyze different procedures for producing CdS QDs. We will be trying Na2S as our sulfur source, which is what we have been using for the production of our ZnS QDs. This will be compared to our other sulfur source, potassium thioacetate. In this article: http://pubs.acs.org/doi/pdf/10.1021/cm0628799 The authors discuss three major points that are important for the best production of CdS QDs. Their reaction utilized 40 mM Ammonium acetate as well as 75 mM ammonium water. They also added the sulfur source last and very slowly, which we will try in today's experiment. (1) a high concentration of ammonium ions compared to cadmium concentration to stabilize cadmium ions as tetraamminecadmium ions; (2) slow supply of sulfide ions into the reaction solution; and (3) the addition of S source must be the final step. Another issue that we are analyzing today is whether any negatively charged amino acids in the sequences of the proteins (BSA, lysozyme, and myoglonin, all have negatively charged amino acids) will affect the formation of CdS QDs. Procedure Part 1: Final Concentrations 10 mM Potassium thioacetate 12.5 uM Myoglobin in Water 1 mM Cadmium acetate in Water 40 mM ammonium acetate Ammonia water for pH adjustment HNO3 or acetic acid? for pH adjustment Deionized Water Part 2: Final Concentrations 12.5 uM Myoglobin in Water 1 mM Cadmium acetate in Water 10 mM *Na2S* in Water 40 mM ammonium acetate Ammonia water for pH adjustment HNO3 or acetic acid? for pH adjustment Deionized Water Solutions were prepared as shown in the image below.