Aim:
Seed-mediated synthesis of Gold-Nanorods (GNR).

Safety data:

Reagent | Hazard | Precaution | 0.001 M HAuCl4 | Skin and eye irritant. Possible carcinogen. | Avoid contact. Wash with water for 15 minutes in case of skin or eye contact. | 0.20 M CTAB | Skin and eye irritant. May be combustible at high temperature. | Avoid contact. Wash with water for 15 minutes in case of skin or eye contact. | 0.15 M CTAC | Harmful if swallowed. Risk of serious damage to eyes. Irritating to skin. Very toxic to aquatic organisms. | Avoid contact or ingestion. Wash immediately with water in case of contact. Rinse mouth and drink plenty of water in case of ingestion. | 0.15 M BDAC | Causes severe skin burn and eye damage. Toxic if swallowed. Causes toxicity to aquatic life. | Avoid contact and ingestion. Do not dispose down the drain. | 0.01 M NaBH4 | Corrosive to skin and eye. | Avoid contact. | 0.004 M AgNO3 | Hazardous to skin and eye and in case of ingestion. | Avoid contact, ingestion. | 0.10 M Ascorbic acid | Mild irritant to skin and eye. Mutagen to mammalian somatic cells. | Avoid contact. |

Materials: * M HAuCl4, 0.20 M CTAB, CTAC, BDAC, 0.01 M NaBH4, 0.004 M AgNO3 and 0.10 M Ascorbic acid.

Procedure:
Seed Solution: * Add 5 mL 0.20 M CTAB solution to 5 mL 0.0005 M HAuCl4 and stir the mixture well. * Add 0.60 mL ice-cold 0.01 M NaBH4 to the stirred solution and further stir the solution vigorously for 2 minutes. * After stirring, store the solution at 25°C.
Growth Solution: * To 5 mL 0.001 M HAuCl4 add 5 mL surfactant mixture containing 0.015 M CTAB, 0.015 M BDAC and 0.015M CTAC. * Mix the solutions well and keep at 25°C. * Add 200 μL of 0.004 M AgNO3 to the solution and mix them. * Add 6 μL of 0.01 M ascorbic acid.
GNR synthesis: * Add 10 μL of the seed solution to the growth solution and store the mixture at 20°C until a distinctive color of the solution has settled.

Analysis: * Perform a UV-Vis spectroscopy on the final product. 2 distinctive peaks should signify of a successful synthesis of GNR. * Take TEM images of the product to measure the average length and width of the GNRs.
Reference:
* Sharma, V., Park, K., & Srinivasarao, M. (2009). Colloidal dispersion of gold nanorods: Historical background, optical properties, seed-mediated synthesis, shape separation and self-assembly. Materials Science and Engineering: R: Reports, 65(1), 1-38.