User:Mary Mendoza/Notebook/CHEM 571 Experimental Biological Chemistry I/2012/09/11

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UV-Vis scans of mole ratio ranging from 120 to 134

  • As indicated in the previous entry, the initial appearance of the Au/BSA solutions were clear and colorless [1].
  • After being given 6 days incubation period, the solutions appeared slightly purple and clear with no fibers suspended.
  • Consecutively, UV-Vis scan were taken for all mole ratios, 120, 128, 130, 132, 133, and 134, to verify the presence of nanoparticles. 150 μL was taken from each solution and transferred to the cuvette using a micropipet.
  • While running the UV-Vis scan, there were background peaks seen in the spectrum graph. To compensate for this addition of peaks, a cuvette containing 150 μL of water was run through the UV-Vis to serve as the baseline by subtracting its peaks from the mole ratio spectra.
  • Graphs are shown below for each mole ratio with the water spectra subtracted in MS Excel. In observing the graphs below, in particular graph: Comparison of peaks, this is similar to the trends from the UV-Vis scans of the first batch of Au/BSA mole ratio solutions [2].



Continuation of UV-Vis scans for pH 8

  • The solutions containing the tris buffer (pH 8) were run through UV-Vis scan for the third time. The UV-Vis scans for each run are listed on the table below.
  • For the third run, a background noise was seen on the raw data in the signal processor interface (computer). A UV-Vis scan of 150 μL of water was taken. The UV-Vis scan of water will be used to account for the background noise seen on the UV-Vis scan reading. The absorbance of water can then be subtracted from the raw spectra of the mole ratios in MS Excel.
graph of run 1, 2, and 3 graph of run 1 and 2 graph of run 3
.1 M .1 M .1 M
.01 M .01 M .01 M
.001 M .001 M .001 M
1×10-4 M 1×10-4 M 1×10-4 M
1×10-5 M 1×10-5 M 1×10-5 M
1×10-6 M 1×10-6 M 1×10-6 M
1×10-7 M 1×10-7 M 1×10-7 M

Preparation of solution with mole ratio 170

  • The previous batch of Au/BSA solutions were disposed. Hence, a new set of solutions were needed to test the effects of tris buffer pH 10.
  • Varying the mole ratio of the Au/BSA was irrelevant for this step since this factor was being held constant. The option of making the solution to mole ratio 170 was a random choice.
  • The stock solution used for the preparation of the new set of Au/BSA solution were provided by faculty, Dr. Miller.
  • The molarity of the BSA stock solution was 2.4268 M and of HAuCl4 was 2150 μM.
  • Again, using the dilution equation, M1V1 = M2V2, the following values were obtained:

VBSA = (1 μM × 6 mL) ÷ 24.226 μM = .248 mL of BSA

VAu = (1 μM × 6 mL × 170) ÷ 2150 μM = .474 mL of HAuCl4

  • After making the appropriate calculations, seven samples were made with the same concentration. Seven solutions were needed to suffice the amount of solutions needed for the serial dilution of tris buffer pH 10.
  • The set of seven solutions of Au/BSA mole ratio 170 were placed inside an oven for 4 h. at 85°C. Before placing the set inside the oven, the solutions appeared clear and colorless liquids.