9/17 (Day 5)
- Following synthesis of a new Au seed, the cubic (C), octahedral (O) and rhombic dodecahedral (RD) were prepared using the same procedure described previously. However, we were advised to switch from preparing our samples in 50mL conical Falcon tubes to 125mL Erlenmeyer flasks. Since we now had to reuse glassware, each flask and beaker had to be washed with Aqua Regia (1 part concentrated nitric acid and 3 parts of concentrated HCl) for 5 minutes and then go through 3-4 rounds of washing with Acetone and Distilled Water.
- For the cubic AuNPs, synthesis occurs through the addition of 5 mL of 100 mM KBr solution, 1 mL of 10 mM HAuCl4 solution, 150 μL of 100 mM ascorbic acid solution, and 2 mL of the Au seed solution made on 9/11 into 50 mL of 100 mM CPC solution in sequence. The cubic solution is incubated under room temperature for 2.5 hours.
- For the octahedral AuNPs, synthesis occurs very similarly to that of the cubic solution without the addition of KBr. However, this solution is incubated under room temperature for 3 hours.
- For the RD AuNPs, synthesis occurs through the addition of 1 mL of 10 mM HAuCl4 solution, 2 mL of 100 mM ascorbic acid solution, and 2 mL of the Au seed solution from 9/11 into 50 mL of 10 mM CPC solution in sequence. This solution is incubated under room temperature for 3.5 hours.
- Following the respective periods of incubation, each solution is centrifuged three to five times at 3500 rpm with 5 mL of warm water. The number of times a solution is centrifuged depends on the amount of precipitate formed. Following the final round of centrifugation, the solutions are redispersed in 150 μL, due to the amount of gold precipitate present in the final solution.
The final solutions are transferred into 1.5mL microcentrifuge tubes and left in the refrigerator for incubation and further SEM analysis.
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