User:Eleni N. Kalivas/Notebook/CHEM-571/2013/08/28

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Objectives

Use two different ways to synthesize gold nanoparticles. The first method requires the use of a protein called bovine serum albumin (BSA). This protein reduces the Au3+ and also encloses and stabilizes the gold nanoparticles. The second method includes using sodium citrate. The sodium citrate also reduces the Au3+ and also encloses and stabilizes the gold nanoparticles.

BSA-AuNP

Protocol:

  • Add 1mL of the 2.54mM gold (HAuCl4) solution to a 10mL volumetric flask
  • Add 1.8mL of BSA solution so that the final concentration of gold is 90X that of BSA
  • Add deionized water up to 10mL
  • Transfer solution to a test tube and cap with aluminum foil
  • Heat in oven at 80C for 3 hours
  • Transfer solution to a plastic falcon tube


RESULTS: When the product was taken out of the oven it appeared to be a relatively clear solution, when it was removed from the oven it appeared to have a purple/burgundy tint to it.

Citrate-AuNP

Protocol:

  • Take 50mL of the HAuCl4 solution from the 250mL volumetric flask, with a .249mM concentration
  • Heat this solution to boiling while stirring
  • Add 1.5mL of 1% (w/v) sodium citrate
  • Boil solution for another 40 minutes (start time 12:52pm - stop time: 1:32pm)
  • Cool to room temperature and measure the volume
  • Determine the final concentration of gold and citrate
  • A 1/10th dilution of the stock solution was used to gather a UV-vis spectra
  • Using Beer's Law the experimental concentration was also determined

Chart 1 (1).png


Observations/Results:

  • 0.01475mmol gold was added to the final volume of 9.5mL, which yields a final concentration of 1.55mM.
  • The sodium citrate was adding to the HAuCl4 while it was still boiling and stirring. Immediately after adding the sodium nitrate the solution turned a light grey then began to slowly get darker and take on a dark purple tone. Once it seemed to be reach a very deep purple it then began to lighten up and become somewhat red. After 40 minutes the solution was left to cool down to room temperature and using a graduated cylinder the final volume was measured to be 9.5mL, which resulted in a final theoretical concentration of HAuCl4 was 0.0054M and of the sodium nitrate was 0.0013 M. After analyzing the graph the peak was not within the typical range, from this it can be concluded that the 1/10th dilution of the stock solution of citrate-AuNP does not have enough gold material which is effecting the absorption peak. Therefore we have decided to make a new dilution from the stock solution and re-run the sample on the UV-Vis.