User:Khyra A. Neal/Notebook/Experimental Biological Chemistry II Notebook/2015/03/17

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March 17, 2015

Objective

  1. Prepare Stock Solutions
  2. Prepare New Citrate Gold Nanoparticles
  3. Determine Concentration of Citrate Nanoparticles
  4. Setup New Reaction

Description

  1. Stock Solutions
    1. 38 mM Sodium citrate
      • 0.11728 g Sodium Citrate in 10 mL H2O
    2. 1% wt HAuCl4
    3. 0.075% wt. NaBH4
      • 0.00358 g NaBH4 in 5 mL 38.8 mM Sodium Citrate solution
  2. Citrate Nanoparticles
    • 90 mL H2O to 100 mL volumetric flask
    • Add 1 mL 1% wt HAuCl4 and stir for 1 minute
    • Add 2 mL 38.8 mM Sodium Citrate and stir for 1 minute
    • Add 1 mL 0.075% wt. NaBH4 and stir for 5 minutes
    • The solution turned a deep burgundy/purple after the addition of 1 mL 0/075% NaBH4
  3. Concentration
    • The concentration was determined using a method as described by Wolfgang Haiss
    1. The absorbance was measured and the surface plasma resonance peak (Aspr) was found to be 539 nm. The ratio of the absorbance at the A529 and A450 was used to determine the diameter of the nanoparticles. The diameter is then used to determine the molar absorptivity (ε450) to calculate the concentration.
      • The diameter was found to be ≈ 6 nm. c= A450 / ε450 = 20.8 nM
  4. New Reaction
    • A new reaction was set up and described on February 10, 2015
    • 2 mmol 30% H2O2 was added instead of 1 mmol and 20 mol % Citrate AuNPs was added
      • 0.1201 g HAuCl4 / (339.785 g/mol) =0.353 mol in 10 mL HAuCl4
      • 0.353 mol / 10 = 0.0353 mmol in 1 mL HAuCl4
      • 0.0353 mmol / 3 mL = 0.2 mmol/ x
      • x= 17 mL AuNPs to add
    • The reaction was removed from heat and was stirred continuously for 2 hours after excess water was added.


Data

Citrate AuNPS.jpg


NOTE

A white solid did not form after water was added to the reaction vessel like expected. Based on the solid not forming, it can be concluded that the reaction did not completely finish. A new reaction will be setup and the reactant amounts are to be adjusted.