User:Dhea Patel/Notebook/Experimental Biological Chemistry Notebook/2012/09/11

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  • to reanalyze AuNP/BSA + Tris buffer solutions with UV-vis spectroscopy
  • to remake AuNP/BSA solutions.


  • Reanalyzing AuNP/BSA + Tris buffer Solutions
    • Please refer to Kay's entry to find that UV-vis was run on the samples containing Tris buffer from last week by centrifuging some of the samples and then running UV-vis on the from 700nm to 200nm.
      • Centrifuging the samples before running UV-vis ensured that the sample run in the UV-vis was solely the supernatant (Au/BSA solution) and not the pallet (protein fibers).
      • The data obtained from the UV-vis shows that only 2 peaks occurred at ~530nm. This may be a consequence of centrifuging the samples before running UV-vis, as the prior week's UV-vis of the samples all had an absorption peak at ~530nm (see graphs under "Data and Calculations").
  • Remaking AuNP/BSA solutions
  1. Please refer to Dr. Miller's Notebook for creating stock solutions of BSA and HAuCl4.
  2. From these stock solutions, 2 test ratios of gold to BSA were made:
    1. 120 Au/BSA: 165μL BSA, 64.5μL HAuCl4, 3.771mL H2O.
    2. 160 Au/BSA: 165μL BSA, 85.9μL HAuCl4, 3.749mL H2O.
  3. These two samples were placed in the oven at 85°C for 1.5 hours to ensure a reaction occurs before making the rest of the concentration ratios.

Data and Calculations

  • Remaking AuNP/BSA solutions
' BSA HAuCl4
Actual Mass (g)0.04030.0073
Formula Mass (g/mol)66430339.79
Volume H2O Added [L]0.0250.01
molarity [M]2.42661E-050.002148386
Stock Solution Concentrations BSA HAuCl4
Theoretical15 uM10 mM
Actual [uM]24.266144812148.385768
Vol [μL]40004000
μM Ratio [Au/BSA] ' '
160BSA [μL]HAuCl4 [μL]H2O [mL]
945.8268342Total μL
  • Absorbance of Various Tris Buffer Concenrations at pH 10 and 8, 1 Week After the Initial Reaction


  • Absorbance of various Tris Buffer Concenrations, ranging from 10μM to 1mM at pHs 10 and 8, 1 week after the initial reaction with the Au/BSP fibers to compare to the absorbance from september 5 (the initial reaction).
  • The mixtures were centrifuged prior to UV-vis. This explains why there are fewer peaks at 540nm this week as opposed to September 5th's data (see below for initial graph).


  • Image of Solutions made today


  • Au/BSA solutions made September 11th, ranging from 60μM to 170μM.
  • These solutions follow the predicted spectrum of homogenous and fibrous solutions.


  • An error occurred when making the stock solution for the HAuCl4 such that the stock was less concentrated than expected. Because of this, the solutions, though made based off an incorrect concentration of HAuCl4, followed the predicted scheme of homogenous solutions from 60 Au/BSA to 134 Au/BSA and fibrous solutions from 135 Au/BSA to 170 Au/BSA. The only unusual result was that the 133 Au/BSA ratio had fibers while the 134 Au/BSA was a homogenous solution.
  • The predicted concentrations of the solutions made today are shown below. These calculations are assuming that all of the HAuCl4 was added to the 5mL water. However, this was not the case, so the concentration of the Gold stock was less than the calculated concentration.

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