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

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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.


HAuCl4/BSA ratio volume of Au (mL) volume of BSA (mL) H2O (mL)
120 .144 0.6 5.256
128 .153 0.6 5.247
130 .155 0.6 5.245
132 .158 0.6 5.242
133 .159 0.6 5.241
134 .160 0.6 5.240


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.
Test Tube volume of tris buffer pH 8 (mL) volume of water (mL) concentration of tris buffer (M)
1 10 0 .1
2 1 9 1x10-2
3 .1 9.9 1x10-3
4 .01 9.99 1x10-4
5 .001 9.999 1x10-5
6 .0001 9.9999 1x10-6
7 .00001 9.99999 1x10-7


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