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Overview
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.
BSA-Au Nanoparticles
- Add 1mL of the (~2.5mM -note the exact concentration) gold (HAuCl4) solution to a 10mL volumetric flask
- Add an appropriate amount of BSA solution so that the final concentration of gold is 90X that of BSA
- Add deionized water up to 10mL
- Transfer solution to a test tube and cap with aluminum foil
- Heat in oven at 80C for 3 hours
- Transfer solution to a plastic falcon tube (with blue cap)
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
Citrate-Au Nanoparticles
- Take 50mL of the HAuCl4 solution from the 250mL volumetric flask. Note the concentration
- Heat this solution to boiling while stirring
- Add 3mL 1.5mL of 1% (w/v) sodium citrate
- Boil solution for another 40 minutes
- Cool to room temperature and measure the volume
- Determine the final concentration of gold and citrate
Stock solutions made
- Gold solution (HAuCl4·3H2O) 0.0245g in 0.2505mL water → 0.249mM
- Sodium Citrate (Na3C6H5O7·2H2O) 0.1010g in 10.0mL → 1.01%
Data
Citrate AuNP
Peak Wavelength = 518 nm
Absorbance at Peak = 0.612
Final Concentration
A450=0.389
Abs (518)/ Abs (450)= .612/ .389= 1.57
A518/A450=1.57
Using the data found here:
1.57 = 12 d/nm and a molar absorptivity of 1*10^8.
ε450=1.09*108 M-1cm-1
Beer's Law gives an equation for the absorption of light and the properties of the solution.
- [math]\displaystyle{ \ A=\epsilon bc }[/math]
c=A450/ε450
c=3.57*10-9 mol L-1
References
Dr. Harting's AU Biomaterials Design Lab
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Project name
Main project page
