User:Alexander Cvitan/Notebook/Experimental Biological Chemistry Lab/2013/08/28

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Contents

Objective

To prepare gold nanoparticles using two separate methods. Procedure taken from Dr. Matt Hartings, found here.

Procedure

BSA-AuNP

Stock Solutions
  • Concentration of Gold Solution (HAuCl4*3H2O) = 2.54mM
  • Concentration of BSA = 15.6μM
Amount of Stock Solution Used
  • 1ml of gold solution is used to prepare the gold nano particles, thus .00254 milli moles of Gold are present.

In order to have 90 times less BSA than gold we need 2.82*10^5 milli moles of BSA.

  • As a result, 1.809 ml of BSA is needed.

Citrate-AuNP

Stock Solutions
  • Concentration of Gold Solution (HAuCl4*3H2O) = .245mM
  • Concentration of Sodium Citrate (Na3C6H5O7*2H2O) = 1.01%
Amount of Stock Solution Used
  • Note, 1.5ml of sodium citrate was used instead of 3ml.

Procedure was followed as written to completion.

After Synthesis of Gold Nanoparticles
  • Final Amount of Solution = 25.6ml

UV-Vis Measurements were taken with a sample of solution that was a 10X dilution. This was done due to the linear relationship that forms with absorbances under the value of 1. As a result, final concentration found must be augmented to fit this change.

Data

Image:AuNP's_Citrate_08-28-13.png

  • Wavelength at Peak = 518.5nm
  • Absorbance at Peak = 0.143 AU (Note this value accounts for the signal due to water)

In order to analyze the data the following reference was utilized, 'Determination of Size and Concentration of Gold Nanoparticles from UV/vis Spectra'
In order to find the concentration of the solution the Absorbance at 450nm needs to be known.

  • Absorbance at 450 nm = .091 AU
  • Using the reference above the particle diameter is 12 nm and the molar absorptivity is 1.09*10^8 1/Mcm
  • Using Beers Law and the reference above the calculated concentration of the diluted sample is 0.834nM
  • Taking into account the dilution the final concentration of the Gold AuNP's prepared using Citrate is 8.34nM
  • Using the initial concentration of gold and the final volume, the concentration of just gold is .00957M

Matt Hartings By your measurements (final volume of your solution), what concentration of gold (not AuNPs just gold) do you expect these samples to have?

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