User:Melissa Novy/Notebook/CHEM-571/2012/09/04

Objectives

• Analyze AuNP/BSA solutions with UV-vis spectroscopy. Data will be posted next week.
• Make Tris buffer solutions at pH values of 8 and 10.
• Refer to Dhea Patel's entry for AuNP/BSA solution ratios, calculations, and images.

Tris Buffer Solutions

• 100 mL of 0.1 M Tris buffer solution requires:

  MW Tris: 121.14 g/mol
  (0.1 mol Tris/1 L) × (121.14 g Tris/1 mol Tris) = 12.114 g Tris/L
  (12.114 g Tris/1 L) × 0.1 L = 1.2114 g Tris/0.1 L
  Theoretical mass of Tris: 1.2114 g

• 1.2114 g of Tris buffer was added to 100 mL of H₂O to make a 0.1 M Tris buffer solution.
• While stirring to ensure even distribution of particles, the pH of the solution was adjusted to 8.0 with drops of 1 M HCl. The total volume of HCl used was about 7 mL.
• Another 100 mL of 0.1 M Tris buffer solution was made and its pH was adjusted to 10.0 with drops of 1 M HCl. The total volume of HCl used was about 1 mL.

Absorbance Data

• Absorbance of AuNP/BSA solutions at concentrations ranging from 60 μM to 170 μM to determine the formation of AuNPs.
• A peak at around 530 nm for the 80 μM solution indicates the presence of AuNPs in solution. A visual confirmation was that the solution was also transparent purple in color.
• No peaks occurred for the other solutions, because no AuNPs formed. These solutions contained yellow-brown precipitate instead. The gold likely did not react with the BSA in the manner intended.

Notes

• The original AuNP solutions did not form nanoparticles, as the HAuCl₄ reacted with the metal spatula. They were yellow in color and the higher ratio solutions contained brown precipitate.
• Visual analysis indicated that all but the 60 and 80 Au/BSA solutions of the second set of AuNP+BSA solutions contained fibers.
• Please refer to Keyun Wang's entry for more observations about the solutions.