Objectives
- Prepare a bovine serum albumin (referred to as BSA) and gold nanoparticle (referred to as AuNP) solution for later testing.
- Prepare a sodium citrate- AuNP solution.
- Determine the concentration of the prepared sodium citrate-AuNP solution using UV/vis.
BSA-AuNP Preparation
General Protocol:
- Add 1mL 2.54mM HAuCl4 solution prepared by Dr. Hartings to an 10mL volumetric flask.
- Add 1.80mL 15.6μM BSA solution to the 10mL volumetric flask.(The concentration of gold in the solution is 90x that of the BSA)
- Add 7.2mL deionized H2O to the 10mL volumetric flask.
- Transfer the solution into a test tube. Cap the test tube with aluminum foil
- Heat in oven at 80°C for 3hrs.
- Store the solution in a blue falcon tube.
Note:Use caution when removing the test tube from oven. The test tube will be hot.
Sodium citrate-AuNP solution Preparation
General Protocol:
- Add 50mL of the prepared 0.295mM HAuCl4 solution to a clean 150mL beaker.
- Heat this solution to a boil while stirring the solution with a magnetic stir bar. Keep the beaker covered with a watch glass while the solution is heating.
- After the solution comes to a boil, add 1.5mL of 1%(w/v) sodium citrate(prepared by Dr. Harting's).
- Cover the beaker with a watch glass and allow to boil and stir for another 40 minutes.
- Remove the beaker from the hot plate and allow to cool to room temperature. Keep the watch glass on the top of the beaker until solution is cooled.
- Measure the volume of the solution.
Table 1. Prepared citrate-AuNP particle solution
UV/vis analysis
- In order to determine the concentration of the solution, the solution was diluted using a 1/10 dilution. 1mL was used for the UV/vis sample.
- To analyze the solution this reference was used.
Figure 1.
- The maximum absorbance of the citrate-AuNP was 0.405 at 518-521nm.
- This wavelength range did not correspond to the supporting reference. This may indicate that too little gold or the incorrect amount of the citrate-AuNP solution was added to the 1/10 dilution. Another dilution will be run during the next meeting in order to determine the concentration of the prepared citrate-AuNP solution and the size of the diameter of the Au particles in the solution.
Notes
- After the addition of the citrate to the HAuCl4 solution, the solution turned a light purple color. This color darkened during the 40min boiling process. Half way through the boiling process the solution turned a deep reddish purple color for approximately 5 min and then changed back to a dark purple color.
- After the BSA-AuNP solution was heated for 3 hours, the solution turned into a dark purple color.
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