User:Omar Choudary/Notebook/Omar Choudary CHEM-571 AU-2011/2012/2012/03/21

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Objective

  • Repeat Fluorescence studies from 3/20/2012 (Second Dye Reaction) to determine if results are reproducible.
  • Measure pH of the three dye solutions to better understand how pH affects absorption and emission.

Description

  • Centrifugation (5 minutes at 13200rpm) for:

1. 166 Au/BSA ratio solution with dye

2. 70 Au/BSA ratio solution with dye

3. BSA/HCl solution with dye


  • Take fluorescence spectrum


  • Measure pH of solutions:

1. 166 Au/BSA ratio solution with dye: pH = 8.13

2. 70 Au/BSA ratio solution with dye: initially pH = 7.62

3. BSA/HCl solution with dye: initially pH = 7.75


  • Add Tris buffer to 70 Au/BSA ratio and BSA/HCl dye solutions to make pH values of all 3 solutions close to 8.13 ( pH of 166 Au/BSA ratio dye solution):

1. 70 Au/BSA ratio solution with dye: added 3 drops to make final pH = 8.07

2. BSA/HCl solution with dye: added 3 drops to make final pH = 8.09


  • Centrifuge all 3 solutions: 5 minutes at 13200rpm


  • Take Fluorescence spectrum

Data

  • Fluorescence spectra before changing pH of solutions. (Second Dye Reaction)

3-21-2012-1.jpg

  • Fluorescence spectra after changing pH of solutions. (Second Dye Reaction)

3-21-2012-2.jpg

  • UV-Vis spectra after changing pH of solutions. (Second Dye Reaction)

3-21-2012-3.jpg

3-21-2012-4.jpg

Notes

  • The Fluorescence spectrum from 3/20 was reproducible.
  • The pH of the 3/20 166 Au/BSA ratio dye solution (second dye solution) had a significantly higher pH than the other two dye solutions from 3/20.
  • The dye is most sensitive at pH's in the 8 to 9 range which is why the pH of all three dye solutions was changed to be near 8.1.
  • After the pH's of the three dye solutions were changed, the Fluorescence spectra of the three dye solutions had the same decreasing trend but the 166 Au/BSA ratio dye solution had a decrease in emission while the other two dye solutions had increases in emission. It can be concluded that the reactions are indeed pH sensitive because the emission peaks were closer together after altering the pH's of the solutions.
  • Next week the pH's of the dye solutions from 2/22 will be analyzed to see if there's a possibility that differences in pH are contributing to the inconsistent results between the 2/22 (first) and 3/20 (second) dye reactions.