# User:Floriane Briere/Notebook/CHEM-496/2011/09/28

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## Objective

We used the same protocol as on the 27th of September, except that we used water as a bufer instead of Tris (whose pH was equal to 7.5). According to our previous experiments, we have already observed that the Gold NPs was more efficient in water, compare to Tris or acetate buffer. So, we should observ better results than the one we had on the 27th of September.

## Description

• Gold NPs synthesis:
1. Add 0.97ml of BSA (15.4µM) + 0.58ml HAuCl4 (4.3mM) + 8.45 water
2. We obtain a 10ml solution ([BSA] = 1.5µM ; [HAuCl4] = 0.25mM)
3. Take a spectrum at T0
4. Place the solution in the oven at 80°C during 2 hours
5. Take spectrum every 30 minutes

## Results

• Curve of the Absorbance as a function of the wavelength:

• Curve of the Absorbance as a function of the wavelength (zoomed in the 550nm area):

• Curve of the Absorbance at 550nm as a function of time:

• Conclusion:

At the end of the experiment, we obtained a purple solution.

Compare to the results we obtained on the 27th of september, we can say that by using water as a buffer, we observe a significant increase of the Absorbance at 550nm during the experiment. So, we can say that some Gold NPs have been synthetized during the experiment. According to all the Gold NPs synthesis we performed in August and September, we can conclude that the Gold NPs is the most efficient when we use water as a buffer and when the temperature is stable during the whole experiment.