Dynamically Tunable Plasmonic Band for Reversible Colorimetric Sensors and Surface-Enhanced Raman Scattering Effect...

Area of Science:

• Nanotechnology
• Materials Science
• Analytical Chemistry

Background:

• Plasmonic nanoparticle (NP)-based colorimetric sensors offer convenient detection but suffer from poor reproducibility and adjustability due to random NP arrangements.
• Developing controllable and reversible sensing platforms is crucial for advancing colorimetric and SERS applications.

Purpose of the Study:

• To create a reproducible and adjustable colorimetric sensor with tunable plasmonic properties.
• To develop a high-quality, dynamic surface-enhanced Raman scattering (SERS) substrate using ordered nanoparticle arrays.

Main Methods:

• Fabrication of a composite material by embedding two-dimensional (2D) gold nanoparticle (Au NP) arrays onto a polyacrylamide hydrogel film.
• Utilizing the swelling-shrinking behavior of the hydrogel to dynamically tune the interspacing distance between Au NPs.
• Characterization of the optical properties (diffraction and plasmonic coupling peaks) and color changes in response to varying water content.

Main Results:

• The composite exhibited reversible color changes (iridescence ↔ violet ↔ golden yellow ↔ red) correlated with water content due to tunable inter-NP spacing.
• The ordered 2D Au NP array structure ensured good reproducibility of the sensor's performance.
• The material demonstrated high sensitivity and reproducibility as a SERS substrate, detecting analytes down to 10^-10 M with <20% relative standard deviation.

Conclusions:

• The 2D Au NP arrays on a hydrogel composite offer a promising strategy for developing high-quality, reproducible colorimetric sensors.
• This platform serves as an effective dynamic SERS substrate with tunable plasmonic properties for enhanced signal detection.