User:Michael F. Nagle/Notebook/Chem 571/2012/09/04

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Objective

  • Using UV/Vis, find optimal mole ratio of HAuCl4 to BSA for nucleation of gold nanoparticles in solution.
  • Prepare .1M Tris buffer at pH's of 8 and 10 to be added, at a wide range of concentrations, to solutions with Au/BSA fibers

Procedure

  • UV/Vis
    • .1mL of each Au/BSA solution was inserted into a quartz cuvette, which went into a Shimadzu UV-2550 Spectrophotometer.
      • These are not the same solutions prepared 8/29, as the HAuCl4 did not react, perhaps due to contamination from using a metal spatula that was not wrapped in parafilm. The solutions used here were prepared by Dr. Miller
    • Cuvette was cleaned between each spectra and the same cuvette was used each time
  • Tris buffer serial dilution
    • After being analyzed via UV/Vis, all HAuCl4 and BSA solutions were centrifuged. The fibers became stuck along the side of the tubes and fluid was dumped.
    • .1M solution of Tris was prepared at pH's of 8 and 10 by Puja Mody
    • 9mL H2O was added to each tube. A serial dilution was completed using Tris buffer at pH of 8.
    • 1mL Tris stock was added to the first tube. 1mL from this tube was moved to the next tube, and so on for the 12 remaining tubes with fibers.

Data

Data for mole ratios from 130-140 was lost. This is because all spectra were saved as data print tables once trials were complete, and the spectra from 130-140 were not double clicked on before "Save" was clicked, and so other spectra were saved in their place. They could not be retrieved since the .spc files were not backed up. Image:AuBSA1.png

Discussion

  • A significant drop in absorbance is seen between mole ratios 120 and 128. This indicates that this may be the point where gold nanoparticles stop going into solution and are only in fibers. However, research by Bakshi, et. al.1, indicates that the optimal mole ratio is from 132-134. More trials are needed to determine where the optimal range is.
  • Dissolution of fibers in Tris should be tested at pH's 8 and 10 because Tris's optimal range is 7-9. We will also replicate previous experiments that used a pH of 10.

References

Bakshi, M.S.; Kaur, H.; Khullar, P.; Banipal, T. S.l; Kaur, G.; Singh, N. Protein Films of Bovine Serum Albumen Conjugated Gold Nanoparticles: A Synthetic Route from Bioconjugated Nanoparticles to Biodegradable Protein Films. J. Phys. Chem. C, 2011, 115 (7), pp 2982–2992


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