Objective
- Using UV/Vis, find which mole ratios of HAuCl4 to BSA result in the most BSA unfolding and formation of formation of protein fibers that include gold nanoparticles.
- Make Tris stock solutions and do serial dilution with HAuCl4 and BSA fibers in Tris buffer
Procedure
- UV/Vis
- On 8.29, samples were made with varying mole concentration of HAuCl4 and BSA. .1mL of each solution was inserted into a cuvette, which went into a UV/Vis Spectroscoper
- Cuvette was cleaned between each spectra, and the same cuvette was used each time
- Tris buffer serial dilution
- Solutions with varying mole ratios of HAuCl4 and BSA were centrifuged. The fibers became stuck along the side of the tubes and liquid was dumped.
- .1M solution of Tris was needed to begin serial dilutions.
- .1M Tris * .1L = .01mol
- .01mol Tris * 121.14g/1mol = 1.21g Tris
- Stock solution of Tris was made at pH 8 and 10.
- 1.21g Tris was added to each tube, with 85mL H2O
- HCl was added dropwise until the pH changed to 8 and 10 in each tube, as indicated by a pH meter. 9mL HCl was added for pH=8 and 2mL was used for ph=10.
- Sufficient water was added to leave the final volume of the solution at 100mL.
- 9mL H2O was put in the first tube to receive 1mL Tris from the stock solution.
- 1mL was taken from the tube with a pipette and moved to the next tube. 1mL from this tube was moved to the next tube, and so on until all get some amount of Tris.
Data
File:BSA AuNP Uv-Vis.xlsx
Discussion
- Concentrations of 128-134 should be retested because a significant drop in absorbancy was observed between these values and 120 and 138. Between the mole concentrations of 120 and 128, and 134-138, a significant change in peak height in seen. This indicates a difference in the amount of gold nanoparticles in solution. The range of 128-134 should be tested again because all other concentrations, higher and lower, have much higher peaks.
- Abigail E. Miller 14:11, 17 September 2012 (EDT):what hypothesis are you testing? did you centrifuge the samples? should you expect a drop in AuNP concentration with fiber formation between 128 and 134? make a graph of Au/BSA ratio versus absorbacne at 520-540 nm max. wavelength.
- Dissolution of fibers in Tris should be tested at pH's 8 and 10 because Tris's optimal range is 7-9. Previous experiments used a pH of 10, which should also be tested so these can be replicated.
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