Robust multilayer thin films containing cationic thiol-functionalized gold nanorods for tunable plasmonic properties

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Gold nanorods possess unique physical properties driving diverse applications.
• Layer-by-layer (LbL) assembly is a versatile technique for fabricating thin films.
• Surface plasmon resonance (SPR) phenomena in nanomaterials are crucial for optical applications.

Purpose of the Study:

• To demonstrate the LbL assembly of thin films with positively charged gold nanorods.
• To investigate the collective SPR coupling and surface-enhanced Raman scattering (SERS) capabilities of these films.
• To explore the fabrication of freestanding nanoscale thin films with tunable properties.

Main Methods:

• Covalent functionalization of gold nanorods with cationic thiol molecules.
• Layer-by-layer assembly of nanocomposite thin films.
• UV-visible spectroscopy for studying SPR coupling.
• Surface-enhanced Raman scattering for molecular detection.
• Characterization of surface morphology, optical, and mechanical properties.

Main Results:

• Uniform distribution of cationic gold nanorods in ultrathin LbL films.
• Observation of collective SPR coupling in the LbL films.
• Successful application in SERS detection of rhodamine 6G.
• Fabrication of freestanding nanoscale films (<50 nm thickness).
• Identification of polycationic gold nanorods' role in film property manipulation.

Conclusions:

• Cationic gold nanorods are effective building blocks for functional LbL films.
• The developed LbL films exhibit tunable plasmonic behavior.
• The films demonstrate robust mechanical properties suitable for various applications.
• This work advances the development of nanomaterials for optical and sensing technologies.