Gold Nanorods Synthesized without CTAB by Strem Chemicals

Table of Contents

Kit Catalog # 96-1549: Gold Gemini Nanorods Kit, CTAB Free (Wavelength 650-850 nm)
Procedure for Re-dispersing Surfactants
Additional Product Details

Kit Catalog # 96-1549: Gold Gemini Nanorods Kit, CTAB Free (Wavelength 650-850 nm)

Each kit contains the following:

79-7010 Gold Gemini Nanorods, CTAB Free (Wavelength 650 nm) 5 ml
79-7015 Gold Gemini Nanorods, CTAB Free (Wavelength 700 nm) 5 ml
79-7020 Gold Gemini Nanorods, CTAB Free (Wavelength 750 nm) 5 ml
79-7025 Gold Gemini Nanorods, CTAB Free (Wavelength 800 nm) 5 ml
79-7030 Gold Gemini Nanorods, CTAB Free (Wavelength 850 nm) 5 ml

Further sizes are also available upon special request.

Product Number LPSR Maximum (nm) Length (nm) Width (nm) Aspect Ratio Color & Form
79-7010 640 - 670 25 - 31 13 - 18 1.7 - 1.9 violet liq.
79-7015 685 - 715 37 - 43 13 - 18 2.4 - 2.8 blue liq.
79-7020 735 - 765 37 - 44 10 - 13 3.4 - 3.7 red-purple liq.
79-7025 785 - 815 40 - 50 10 - 13 3.8 - 4.1 red-orange liq.
79-7030 835 - 865 48 - 55 9 - 12 4.6 - 5.3 maroon - purple liq.

  • Storage Conditions: Store at 4 °C – 8 °C. Do not freeze.
  • Concentration: >30 µg/ml
  • pH: 5.5 - 7.5
  • Stabilizer: Amphiphilic Agents
  • Solvent: Stabilized with amphiphilic agents in conductivity grade water (18.0 MΩ cm-1)
  • Optical Density: 1.0 - 1.2
  • Shelf Life: 12 months

Gold Gemini Nanorods, CTAB Free (Wavelength 800 nm).
Sold in collaboration with SONA Nanotech

Procedure for Re-dispersing Surfactants

The unique surfactant technology that underpins the production of the SONA gold nanorods (GNRs) provides some considerable advantages over GNRs prepared using the cetyltrimethylammonium bromide (CTAB) synthesis technique. These surfactant technologies result in exceptionally stable gold nanorods, but in some cases, when a GNR sample is exposed to temperatures well below room temperature for a long period of time (as would be typical of their recommended storage conditions), precipitated surfactant will be observed in the solution. This however does not affect the amount of GNRs suspended in solution, and neither is it a sign of an irreversible aggregation process through which GNRs are destroyed, as is usually the case with other CTAB prepared GNRs. The following procedures are recommended to homogenize the solutions.

  1. 650, 700, and 750 nm wavelengths. Place the GNR containing vial in a warm water bath (30-35 °C) for about 15 minutes. Remove the vial from the bath and gently swirl the solution inside. Then visually examine the contents to check for any remaining precipitated surfactant, and if precipitated surfactant is still visible, the process is repeated until the solution clears.
  2. 800 and 850 nm wavelengths. Additional warming will be needed to homogenize the solution because the surfactants used to prepare the GNRs have longer nonpolar chains. In this case, the GNR containing vial is placed into a warm water bath (around 45 °C) for a period of 20 to 25 minutes. The vial is then removed from the bath and the solution is gently swirled inside (it will have the appearance of a thick gel). The contents are then visually examined for any remaining precipitated surfactant. The presence of the high rheology surfactant may demand further warming at 45 °C for about 15 minutes to clear the solution. It must be noted that during heating the solution may look clear at various times, but when the solution is swirled the surfactant will come out of solution. The solution is considered to be homogenized when the shaken solution results in the entrapment of air bubbles inside the visco elastic gel rather than surfactant precipitating out.

Additional Product Details

Gold nanorods (GNRs) are minute particles whose surface plasmon resonance frequencies can be modified as a function of aspect ratio, giving these anisotropic particles optical properties that enables them to be employed in a wide range of applications covering the electromagnetic spectrum from the visible to the near-infrared region.1,2 In addition, GNRs have been employed in several biomedical applications, such as contrast agents for optical biomedical imaging and their hyper thermal effects.

A major barrier in the application of GNR-based materials, particularly for in-vivo applications such as hyperthermal cancer treatment, is the efficient exchange and removal of cetyltrimethylammonium bromide (CTAB) — the surfactant employed exclusively in the large scale synthesis of GNRs. As a cytotoxic, cationic surfactant, CTAB has a very low critical micelle concentration3-5. Although its role in the synthesis of the gold nanorods is still a debatable topic, it is usually believed that the CTAB creates a strongly adsorbed bilayer around the surface of the growing gold particle.6-8

The CTAB concentration that is typically employed in the synthesis is 100 times its critical micelle concentration or 0.10 M, which means a considerable amount of CTAB is present in the bulk of the solution after the GNRs are prepared, thus stabilizing the GNRs (prevents them from self-aggregating in solution).6

The CTAB surfactant, which is essential for GNR synthesis, is a major barrier to in-vivo applications. Several techniques have been employed to partially exchange or “remove” the CTAB including treatments with surface active materials such as PEGylated thiols or other polymers, and frequent solvent washing.9-11

However, during surfactant exchange, CTAB-coated GNR dispersions are invariably destabilized, leading to particle aggregation and low recovery yields of GNRs. Additionally, these surface modified GNRs are often contaminated with residual CTAB.9

Find Out More About Gold Nanorods Synthesized without CTAB


  1. Murphy, C. J.; Jana, N. R. Adv Mater 2002, 14, 80-82.
  2. Murphy, C. J.; Thompson, L. B.; Chernak, D. J.; Yang, J. A.; Sivapalan, S. T.; Boulos, S. P.; Huang, J.; Alkilany, A. M.; Sisco, P. N. Current Opinion in Colloid & Interface Science 2011, 16, 128-134.
  3. Fadeel, B.; Garcia-Bennett, A. E. Adv. Drug Deliv. Rev. 2010, 62, 362-374.
  4. Alkilany, A. M.; Thompson, L. B.; Boulos, S. P.; Sisco, P. N.; Murphy, C. J. Adv. Drug Deliv. Rev. 2012, 64, 190-199.
  5. Dharaiya, N.; Chavda, S.; Singh, K.; Marangoni, D. G.; Bahadur, P. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2012, 93, 306-312.
  6. Nikoobakht, B.; El-Sayed, M. Langmuir 2001, 17, 6368-6374.
  7. Nikoobakht, B.; El-Sayed, M. Chemistry of Materials 2003, 15, 1957-1962.
  8. Johnson, C. J.; Dujardin, E.; Davis, S. A.; Murphy, C. J.; Mann, S. Journal of Materials Chemistry 2002, 12, 1765-1770.
  9. Hauck, T. S.; Ghazani, A. A.; Chan, W. C. W. Small 2008, 4, 153-159.
  10. Kinnear, C.; Dietsch, H.; Clift, M. J. D.; Endes, C.; Rothen-Rutishauser, B.; Petri-Fink, A. Angewandte Chemie 2013, 125, 1988-1992.
  11. Kinnear, C.; Burnand, D.; Clift, M. J. D.; Kilbinger, A. F. M.; Rothen-Rutishauser, B.; Petri-Fink, A. Angewandte Chemie International Edition 2014, 53, 12613-12617.
  12. Vigderman, L.; Manna, P.; Zubarev, E.R. Agnew. Chem. Int. Ed. 2012, 51, 636-641.

This information has been sourced, reviewed and adapted from materials provided by Strem Chemicals.

For more information on this source, please visit Strem Chemicals.

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