Gold Nanorods are one of the most interesting kind of nanoparticles as they are characterized by unique optical properties.

Despite a huge interest in this kind of nanostructures, the actual synthetic protocol are difficult to follow for someone not skilled in the field. Labion developed a synthetic route that is more efficient compared to the previous one present in the scientific literature. To make this protocol more accessible and easier to repeat we published a video articles on the Journal of Visualized Experiments.

The video shows step by step how to prepare gold nanorods using hydroquinone as reducing age. Besides, the video exlain how to tune the aspect ratio of the nanorods in order to obtaine the desidered particles.

You can freely look at the video on this page:

A brief resume of the protocol :

Preparation of the gold seeds

1. Prepare 5 ml of hexadecyltrimethylammonium bromide (CTAB) solution (200 mM). To allow the complete dissolution of CTAB warm the suspension at 40°C under ultrasonication until becomes clear and let the solution cool down to room temperature.

2. Prepare 5 ml of tetrachloroauric acid (HAuCl4) solution (0.5 mM).

3. Mix HAuCl4 solution to the CTAB solution under vigorous magnetic stirring. (temperature must be kept constant at 27 °C)

4. Add to the previous mixture 600 μl of sodium borohydride (NaBH4) solution (10 mM) just prepared with water cooled at 4 °C.

5. Solution must change color immediately

6. Stir for 20 min before use.

2. Preparation of gold nanorods.

1. Prepare 5 ml of hexadecyltrimethylammonium bromide (CTAB) solution (100 mM) and Hydroquinone (40 mM). To allow the complete dissolution of CTAB warm the suspension at 40°C under ultrasonication until becomes clear and let the solution cool down to room temperature.

2. Prepare 200 μl of silver nitrate (AgNO3) solution (4 mM).

3. Prepare 5 ml of tetrachloroauric acid (HAuCl4) solution (1 mM).

4. Add the silver nitrate solution (1) and HAuCl4 solution (2) to the solution of CTAB and hydroquinone under magnetic stirring

5. Immediately after add 12 μl of the seeds suspension

6. leave the suspension under stirring for 60 – 90 minutes

3. References:

If you prepare gold nanorods according to this method please cite:

Morasso, C., Picciolini, S., Schiumarini, D., Mehn, D., Ojea-Jiménez, I., Zanchetta, G., Vanna, R., Bedoni, M., Prosperi, D., Gramatica, F., Control of size and aspect ratio in hydroquinone-based synthesis of gold nanorods. J Nanopart Res (2015) 17: 330. doi:10.1007/s11051-015-3136-9

and

Picciolini, S., Mehn, D., Ojea-Jiménez, I., Gramatica, F., Morasso, C. Hydroquinone Based Synthesis of Gold Nanorods. J. Vis. Exp. (114), e54319, doi:10.3791/54319 (2016).