To test the powder we had acquired, we first ran a thin-layer chromatography test on the powder using 20% methanol and 80% DCM. The results showed that the powder we had acquired was mostly indigo, but also had a little bit of impurities in it. Then, we ran an IR test and Proton NMR test on the powder. From the results, we are sure that we have indigo, but it contained some impurities. Then, we created our indigo with biosynthetic methods
Biosynthesis of tryptophan using E.coli involves three major steps. First, glucose in the bacteria is condensed to phosphoenolpyruvate (PEP) in the central metabolism pathway. Then, PEP undergoes the common aromatic pathway, where it is converted to 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) then to chorismate (CHA). At this point, the genes prephenate dehydrogenase (tyrA) and prephenate dehydrase (pheA) were blocked to prevent the CHA from being converted to tyrosine, and, with the help of tryptophanase BA (trpBA), we were able to convert the CHA into our desired tryptophan. Finally, after another enzyme called tryptophanase-A (tnaA) will convert all of our synthesized tryptophan to indole.
Meanwhile, pTacFd911 will produce an enzyme called Flavin-containing Monooxygenase, abbreviated as FMO, that spontaneously converted indole to indoxyl, or 3-hydroxyindole, over the course of 14 hours.
Finally, we got our indigo by mixing appropriate dilutions of whole fermentation broth (i.e., cells and medium ) with dimethylsulfoxide (DMSO) to solubilize the indigo, which has been converted from indoxyl by oxidation when in contact with air. Then, we proportionally mixed the indigo and silver nanoparticles. If we were to create a dye solution that contained 100 ppm of silver nanoparticles and, we would add 0.1g of AgNP to 9.9 g of indigo and add the entire mixture to 100 mL of water.
After we had dyed our cloth, we used computer models to estimate and help visualize the effectiveness of the mask against viruses and bacteria. We tested the effectiveness using some concentrations of indigo and silver, then gave the data to our modeling and CS team for processing. Here is the model they have made.
Another comes in when we have the results from our survey on the suitable price for our masks, and the relationship between concentrations and effectiveness. Using this model, we can find a balance between the price and performance, and also the amount of the two ingredients we would have to use for one mask.