Chiral Shape Engineering Combined with Bimetallic Nanostructures for High-Performance Plasmonic Sulfide Sensors

Abstract

Combining chiral shape engineering with the plasmonic sensor features significantly enhances sensor performance and effectively avoids potential background interference. These advantages suggest that chiral nanoparticles could provide valuable insights into addressing defects or shortcomings in traditional plasmonic sensors. Herein, to address the common drawback of performance degradation due to line width broadening in plasmonic sulfide sensors during sulfidation, we designed a distinctive intrinsically chiral bimetallic core–shell plasmonic nanoparticle. The chiral gold core provided strong chiroptical activities, enriching the spectral features, including bipolar peaks and zero-crossing points, while the silver shell was used for sulfide sensing. Remarkably, this chiral plasmonic sulfide sensor demonstrated exceptional sensitivity and clarity. Specifically, the zero-crossing point in the circular dichroism spectrum serves as an easily recognizable tracking feature, leveraging the trend of line width broadening to enhance sensor responsiveness. Particularly, at a sulfide concentration of only 5 μM, the zero-crossing point shift reached up to 170 nm, with a maximum shift limit of 208 nm, surpassing all previously reported plasmonic sulfide sensors. Finally, the well-defined structure of this chiral-core sensing-shell design offers an alternative fabrication approach for expanding the chiral plasmonic sensing platform, allowing for flexible replacement of the shell material to meet specific sensing requirements.