User:Monika Gasiorek/Notebook/CHEM-571 2014F/2014/08/27

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August 27, 2014 Preparation of Stock Solutions & Culture Tubes We made 50 mL of a 2.512 mM solution of HAuCl4. 0.043 g of solid HAuCl4 in 50 mL volumetric flask We then made 50 mL of a 250 μM solution of lysozyme. 0.179 g of solid lysozyme in 50 mL volumetric flask Finally, we made 50 mL of a 2.512 x 10-4 M solution of HCl. 25 μL of 0.5 M HCl was added to 49.975 mL of H2O NOTE: this needs to be re-done to match the concentration of the HAuCl4 stock, or 2.512 mM. 6 culture tubes were prepared using the stock solutions to observe colloid versus fiber formation given different ratios of [Au]:[protein]. The table below demonstrates the amounts of each stock solution and water added to 6 test tubes, each containing 5 mL of solution total. Au (mL) Lysozyme (mL) H2O (mL) [Au]:[lysozyme] 2.5 2.5 0 10:1 2.5 1.25 1.25 20:1 2.5 0.835 1.665 30:1 2.5 0.625 1.875 40:1 2.5 0.5 2 50:1 2.5 0.415 2.08 60:1 NOTE: The amount of Au in each tube was intended to be 0.5 mL, or 1/10 the volume of the final solution. Using a stock solution with a [H+] of 2.512 mM, the concentration of [H+] in the final 5 mL solution would be 2.512 x 10-4. This would give a solution of 3.6. Because we used 2.5 mL of Au in each tube, or 1/2 the volume of the final solution, our culture tubes contained a higher [H+] and therefore had a lower pH of 2.9. Each test tube was covered in foil and placed in an oven at 80°C for 3 hours. Kinetics of AuNP Formation A 150 mL beaker containing approximately 100 mL of water was heated to 80°C. 3 culture tubes were prepared each containing 0.5 mL of 2.512 mM HAuCl4, 0.167 mL of 2.512 x 10-4 M lysozyme, and 4.333 mL of H2O, giving a [Au]:[protein] of 30:1. The test tubes were covered with foil and placed in the beaker of 80°C water. 2.5 mL of one sample was placed in a plastic cuvette at time point 0 hr, pre-heating, to set a baseline UV-Vis spectrum from 800 nm to 360 nm. Another 2.5 mL aliquot of the samples was taken every 0.5 hrs and a respective UV-Vis was recorded from 800 nm to 360 nm until no more sample solution remained. Spectra were ultimately obtained at time-points 0, 0.5, 1, 1.5, 2, 2.5 hrs.