Modulatory Functionalization of Gold Nanorods Using Supramolecular Assemblies

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Gold nanorods (GNRs) are versatile nanomaterials with applications in sensing, imaging, and therapy.
• Conventional methods for GNR functionalization can be limiting in terms of surface-charge tunability and robustness.
• Achieving reversible phase transfer and controlled surface modification of GNRs remains a challenge.

Purpose of the Study:

• To develop a facile and versatile method for functionalizing gold nanorods (GNRs) with tunable surface charges.
• To enable reversible phase transfer of GNRs between aqueous and organic media.
• To expand the potential applications of GNRs through enhanced fabrication techniques.

Main Methods:

• Preparation of trimethylammonium (TMA) GNRs from cetyltrimethylammonium bromide (CTAB) GNRs via ligand exchange.
• Formation of electrostatic assemblies of TMA-GNRs with oleate ions (OA-GNRs).
• Reversible disruption of assemblies using HCl for phase transfer and re-formation of TMA-GNRs.

Main Results:

• Successfully fabricated robust GNRs with tunable surface charges.
• Demonstrated facile reversible phase transfer of OA-GNRs between water and hexane.
• Showcased the ability to re-form aqueous-soluble TMA-GNRs by disrupting OA assemblies.
• Enabled the synthesis of negatively charged GNRs, such as 11-mercaptoundecanoic acid (MUA) GNRs, which are difficult to prepare directly.

Conclusions:

• The developed supramolecular-assembly-mediated functionalization offers a versatile platform for GNR modification.
• This method facilitates controlled phase transfer and surface-charge tuning of GNRs.
• The approach is expected to broaden the applications of GNRs in sensing, biomedical imaging, photothermal therapies, and drug delivery systems.