User:Puja Mody/Notebook/Chem 571: Gold Nanoparticles/2012/09/05

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Day 3


  • Remake certain AuNP/BSA solutions at specific concentrations to retest using UV-Vis to check/clarify discrepancies because there seemed to be a very low absorbance as compared to the other concentration samples.
  • Centrifuge the gold solutions in order to separate the fibers and then combine the fibers with the Tris buffer at various concentrations in order to test how long it takes for the fibers to (if it does) re-suspend in the solution.


  • The AuNP stock solution from yesterday was combined with a new stock solution of BSA. The concentrations that were retested were: 120, 128, 130, 132, 133, 134. These samples were then placed in the oven for four hours in order to allow for the BSA to unfold and to be wrapped around the AuNP. These solutions were made by Dr. Miller on Friday. See her notebook for mass, volume and concentration values.
  • The AuNP solutions that has been used previously were meanwhile transferred from glass test tubes to plastic ones in order to prepare them for centrifuging. The centrifuging was necessary in order to separate out the fibers as best as possible from the solution.
  • The AuNP fibers were centrifuged for five minutes at a speed of 3000 rpm at a temperature of 10°C. * After centrifuging, the AuNP fibers were separated from solution by pipetting out as much of the supernatant as possible prior to adding the tris buffer. 7 test tubes which had centrifuged out the most of the AuNP fibers were used for the next step. Because it was the amount of Tris buffer that was being varied, the specific 7 test tues were not recorded.
  • A serial dilation was used in order to place various concentrations of the tris buffer and water into the test tubes. The concentrations ranged from .1M to 1×10−2 to 1×10-7. We made 100mL of tris buffer at a concentration of .1M. We made the solutions by serial dilution directly in the test tubes with the fibers but were careful to not pipette out any of the fibers as we were doing the dilution.
  • After these new solutions were made, they were placed in UV-Vis two times. each time to test if the fibers had been dissolved into the tris buffer solution. The first time point was immediately after the buffer and fibers were combined and the second run was 1 hours later.


  • Retested concentrations:
    1. Solutions were made with the mole ratios of

(HAuCl4/BSA) 120, 128, 130, 132, 133, and 134. Volume of HAuCl4 stock solution was calculated for each tube and inserted. The water needed for each tube was calculated by subtracting the volume of HAuCl4 stock solution and BSA stock solution from 6mL.

      1. m1v1=m2v2
      2. 15μM*(volume BSA stock

solution) = (1.5*6)

        1. 0.6mL BSA stock

solution in each tube

      1. 7520μM*x mL=6mL*(1.5*120μM)
        1. 0.143mL HAuCl4

stock solution

        1. 5.257mL H2O
      1. 7520μM*x mL=6mL*(1.5*128μM)
        1. 0.153mL HAuCl4

stock solution

        1. 5.247mL H2O
      1. 7520μM*x mL=6mL*(1.5*130μM)
        1. .155mL HAuCl4

stock solution

        1. 5.245mL H2O
      1. 7520μM*x mL=6mL*(1.5*132μM)
        1. 0.157mL HAuCl4

stock solution

        1. 5.243mL H2O
      1. 7520μM*x mL=6mL*(1.5*133μM)
        1. 0.159mL HAuCl4

stock solution

        1. 5.241mL H2O
      1. 7520μM*x mL=6mL*(1.5*134μM)
        1. 0.160mL HAuCl4

stock solution

        1. 5.240mL H2O


Test Tube Tris Buffer (mL) Water (mL) Concentration of solution M
1 10 0 .1 M
1 1 9 1 x 10^-2 M
1 1 9 1 x 10^-3 M
1 1 9 1 x 10^-4 M
1 1 9 1 x10^-5 M
1 1 9 1 x 10 ^-6 M
1 1 9 1 x 10^-7 M

New concentrations of remixed AuNP/ BSA samples for UV-Vis

Concentration mL of AuNP mL of BSA mL of H2O
120 0.144 0.6 5.256
128 0.156 0.6 5.247
130 0.155 0.6 5.245
132 0.158 0.6 5.242
133 0.159 0.6 5.241
134 0.16 0.6 5.24


  • The tris buffer solutions were placed in a UV-Vis a total of three times. The first two tests were 1 hours apart. The Final trial was done on September 11.
  • Graphs for runs 1 and two of the Tris buffer solutions with the fibers. The excel spreadsheets can be found in the next entry

runs 1 and 2