User:Mary Mendoza/Notebook/CHEM 571 Experimental Biological Chemistry I/2012/09/05

Preparation of specific Au/BSA mole ratio solutions

• Evaluating the peaks from the graph of the initial UV-Vis scan of Au/BSA solutions[[1]], it is evident that there are significant peaks ranging from mole ratios, 120, 128, 130, 132, 133, and 134. Hence, it was decided to prepare a set of new solution of the mentioned mole ratios to verify whether the drop between peaks are significant.
• Using the prepared Au and BSA stock solutions from the previous lab, volumes needed for Au/BSA solutions were calculated.
• The volume for BSA was held constant to 0.6 mL so as the total volume of the Au/BSA solution to 6 mL.
• The same calculations were used for determining the volume needed for Au and water. [[2]]
• After combining the three substances, Au, BSA, and water, into solution, the solutions were wrapped in foil and placed in the oven for 4h. at 85°C.
• The initial appearance of the solutions were clear and colorless liquids.

Testing the effect of Tris Buffer pH 8

• The Au/BSA solution made from August 29 was transferred to plastic centrifuge tubes.
• The plastic centrifuge tubes which now contains the Au/BSA solutions were placed balanced inside the centrifuge chamber. The conditions were set to 3000 rpm at 10°C for 5 min.
• When the centrifuge was over, the supernatant from the Au/BSA solutions were removed by pipet.
• The tris buffer (pH 8) was added by serial dilution using micropipet. The ratio of the volume of tris buffer an water are listed on the table below.
• The solutions were allowed to mix by venting. Three runs of UV-Vis scans were done for all solutions. The runs were scheduled in 1 h. intervals. 150 μL of the solution was taken using a micropipet. A single cork black cuvette was used for all runs.
• The first run was scheduled at 2:30 PM followed by the second run at 3:30 PM.
• The third run was scheduled for next meeting on September 11, 2012.