User:Keyun Wang/Notebook/Experimental Biological Chemistry I/2012/11/28

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  • Au/ADA samples made on 2012/11/27 were ran on UV-vis spectrophotometer and Atomic Absorption Spectrometer, results were analyzed.
  • Au/ADA samples were resuspended in a range of Tris buffers to test resuspension based on concentration of buffer and pH.

Procedure for Running Au/ADA samples on UV-vis Spectrophotometer

  • 3mL of Au/ADA samples with the following mole ratios were analyzed using UV-vis spectrophotometer.
  • 3mL of distilled water was run on UV-vis under spectrum method followed by test samples with above mole ratios. The absorbance obtained from wavelength range 200nm to 800nm were used as base line correction for the Au/ADA samples.
  • Both reference and test samples were loaded into quartz cuvette with 10.0mm pathlength.

Results for Running Au/ADA samples on UV-vis Spectrophotometer

  • The Au/ADA samples made with dialyzed ADA proteins all appeared purple with purple fiber formation at the bottom of tubes. A picture of the samples after 4 hours of heating is shown in picture below:

[Insert Picture]

  • The result indicated that the lack of salt in samples might have an affect on nanoparticle aggregation formation. The lack of salt in solution might lead to ADA proteins to wrap around gold in solution at a lower temperature. The formed gold nanoparticles might have different isoelectric points that engages protein aggregations.
  • While the fiber formation can be due to lack of salt in solution that encouraged nanoparticle aggregation, the fiber formation might also be affected by the usage of plastic falcon tubes during the reaction.
  • The absorbance obtained from UV-vis spectrophotometer were plotted on a graph for all Au/ADA samples. The graph was plotted with absorbance versus wavelength scanning from 200nm to 800nm shown below:

  • From the graph above, it can be shown that there the trend for all Au/ADA samples appeared similar, and that there were no significant difference in gold concentration between each Au/ADA samples solutions. This might indicate that the ratio between Au and dialyzed ADA in solution does not determine gold nanoparticle formation.
  • Comparing the all samples, including water, at a specific wavelength:525nm, it can be seen that there were no significant difference between water and all Au/ADA samples. A data table showing the samples run and absorbance at 525nm is shown below:
Au/ADA samples Absorbance at 525nm
Standard Deviation:0.001566699
  • A graph is made with absorbance of each sample at wavelength 525nm versus water and all Au/ADA samples:

  • From the graph above, it can be concluded that there was no significant differences between the absorbance between water samples and each Au/ADA samples due to low standard deviation. This indicates that there is no relationship between the mole ratios of Au/ADA in solution and the gold nanoparticle formation in solution.
  • The data can be compared against the Au/ADA solution made on 2012/11/27. While the Au/ADA before dialysis appeared to have influence between the mole ratio of gold to ADA and concentration of gold nanoparticles in solution, the Au/ADA samples after dialysis does not. This can be explained by the presence of salt in solution that encouraged gold nanoparticle formation but can stabilize the protein nanoparticles to prevent nanoparticles from aggregating.
  • Furthermore, the solutions for Au/ADA samples before dialysis did not appear purple, while solutions for Au/ADA samples after dialysis formed purple solutions and purple fibers. This can also be explained by the presence of salt in solution. The presence of salt might interact with gold nanoparticles in a way that encouraged gold nanoparticle configuration that does not absorbce at 525nm. The absence of salt in solution might allow gold nanoparticle to adapt another confirmation that does absorb at 525nm.

Procedure for Running Au/ADA samples on Atomic Absorption Spectrometer

  • The same sample of Au/ADA were run on Atomic Absorption Spectrometer.
  • Atomic Absorption Spectrometer was calibrated by running HCl with gold at the following parts per million:
  • HCl was ran to for blank, and water was ran to set base line.
  • Au/ADA samples were run, and the sample tubing was raised with distilled water after each sample.

Results for Running Au/ADA samples on Atomic Absorption Spectrometer

  • The HCl with gold for calibration made up a calibration curve for establishing the concentration of Au/ADA samples. The absorbance measured for HCl with gold were listed in the following table:

Procedure for Au/ADA Resuspension in Tris Buffer

Results for Au/ADA Resuspension in Tris Buffer

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