User:Daniel-Mario Larco/Notebook/AU Biodesign Lab - 09/03/2013/2013/08/28
|Biomaterials Design Lab||Main project page|
Synthesize two different sets of gold nanoparticles. In one set, Au3+ is reduced by a protein (bovine serum albumin, BSA) and the synthesized nanoparticle is also surrounded and stabilized by BSA. In the second set, Au3+ is reduced by citrate, and the AuNP is stabilized by citrate in solution. The BSA-AuNPs are purple in color and the citrate-AuNPs are more of a burgundy (reddish) color.
This procedure was taken from the following reference and has been used by our previous two Experimental Biological Chemistry groups.
* In this experiment the stock solution had a concentration of 2.54mM
* In this experiment the appropriate volume of BSA needed was calculated and found to be 0.001809 L (1.809mL).
* When the test tube was removed from the oven after 3 hours, it was observed that filaments had formed which is an indication that the BSA/Gold ratio was not correct. This was most likely due to an error when transferring the required volumes of both solution to the volumetric flask.
Stock solutions made Gold solution (HAuCl4·3H2O) 0.0100g in 0.0100mL water → 2.54mM BSA solution 0.0104g BSA (MW = 66776g/mol) in 0.0100mL water → 15.6μM
- 50.5mL of the 0.249 mM HAuCl4 solution
- Almost instantly after adding the sodium citrate the solution turned purple and gradually changed to a red/burgundy
color after about 4 minutes.
- After about 30 minutes of boiling, about 5mL of deionized H2O were added to the solution to replace the
H2O lost by evaporation.
- Once cooled, the volume of the solution was measured to be 25mL
- Determining the final concentration of gold and citrate required us to calculate the initial amounts of gold and
citrate in the initial solution.
Gold: 0.05L * 2.49 *10^-4 M = 1.245*10-5 moles of Au. Citrate: 0.0015L * (0.101g/0.01L) * 1mol citrate/294g = 5.15*10-5 moles of citrate
- Final Concentrations Gold: 1.245*10-5 / 0.025L = 4.98*10-4 M Citrate: 5.15*10-5 / 0.025L = 2.06*10-3 M
solution (which would carry out the reaction in a closed system). We should be able to bring the solution to a boil on the bench top.
Stock solutions made
filled with deionized water and was put in the UV-Vis before filling the same cuvette with our diluted sample in order to subtract errors from the actual data.
The data was analyzed using thisthis reference
This is a graph of the results of the UV-Vis of the sample.
The maximum recorded was of 0.158 and this occured between 522nm and 525nm.
Analyzing this maximum absorbency allowed us to
determine that the size of the gold nanoparticles was about 14nm, which allowed us to calculate the
concentration of gold nanoparticles in the solution. The concentration was found using the equation
A450 = 0.158
c= 8.98E-10 M*cm