User:Daniel-Mario Larco/Notebook/AU Biodesign Lab - 09/03/2013/2014/01/28

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The goal of this experiment is to synthesize citrate protected gold nano particles and determine their size using this this reference .


  1. Prepare stock solutions
    1. Dissolve 39.4mg of HAuCl4 into 10mL of de-ionized water
    2. Dissolve 250mg of the citrate sodium salt into 25mL of water
  2. In a beaker mix 50mL of water and 1.158mL of the gold stock solution
  3. Bring solution to a boil
  4. Add 0.5mL of the citrate sodium solution and reflux for 30 minutes
    1. Note color change from dark blue to red

Data Analysis

  1. Place 1/10 dilution of the nano particle solution with water in an Eppendorf tube
  2. Take UV-Vis spectra
  3. Measure the size of the nano particles using this this reference.


A first solution of nano particles was prepared rolling the volumes in the protocol but no color change occurred possibly because the amount of gold was insufficient. The same procedure was used to prepare a second solution only this time using 2mL of gold solution. Upon the addition of citrate sodium solution the color changed to dark blue then red. Changing the ratio of gold to citrate may alter the final size of the nano particles which is why a third solution was made with the same ratios but higher volumes.


0.0413 g of HAuCl4 were dissolved in 10mL of water to give a 10.48 mM solution 250mg of citrate sodium were dissolved in 25mL of water to give a solution with a 10mg/mL concentration

The first solution was made with 1.158mL of the gold solution and 0.5mL of the citrate solution. This solution did not make nano particles The second solution was made with 2mL of the gold solution and 0.5mL of the citrate solution The third solution was made with 2mL of gold and 0.864mL of citrate solution The fourth solution was made with 3mL of gold and 0.375mL of citrate solution

The second, third and fourth solutions successfully formed nano particles. The fourth solution however also formed a precipitate which suggests too much cold was added.

The resulting nano particles from the second and third solutions were between 12 and 13 nm wide which was too small for our experiment.

The most likely cause of these errors was established to have been some error in the calculations.