Interfacial Bilayer Engineering Enables Year-Long Stable Gold Nanorods with Enhanced Plasmonic Sensing

Area of Science:

• Nanotechnology
• Materials Science
• Analytical Chemistry

Background:

• Gold nanorods (GNRs) are valuable for optical sensing due to their tunable plasmonic properties.
• Conventional cetyltrimethylammonium bromide (C16TAB) coatings lead to instability and etching, limiting GNR applications.

Purpose of the Study:

• To develop an interfacial engineering strategy for enhanced GNR stability and sensing.
• To improve the long-term colloidal and optical stability of GNRs in aqueous solutions.
• To amplify plasmonic optical responses for more sensitive detection.

Main Methods:

• Reconstruction of GNR surface bilayers using octadecyltrimethylammonium bromide (C18TAB).
• Characterization of GNR adsorption, surface charge density, and colloidal/optical stability.
• Evaluation of etching kinetics and plasmonic response amplification.
• Construction and testing of sensing arrays with C18TAB-stabilized GNRs.

Main Results:

• C18TAB forms denser, more robust bilayers on GNRs, achieving over 330 days of stability.
• Enhanced adsorption and surface charge density improve stability and responsiveness.
• Accelerated etching kinetics and amplified plasmonic responses were observed.
• Sensing arrays demonstrated nanomolar antioxidant detection and high-resolution discrimination.

Conclusions:

• The C18TAB interfacial engineering strategy significantly enhances GNR stability and sensing capabilities.
• This approach offers simultaneous improvements in stability and responsiveness across various gold nanostructures and etchants.
• The findings provide a generalizable design principle for robust plasmonic sensing in complex environments.