Colorimetric and SERS dual-mode detection of lead Ions based on Au-Ag core-shell nanospheres: featuring quick...

A novel strategy for colorimetric and surface-enhanced Raman scattering (SERS) dual-mode sensing of the lead ions (Pb²⁺) was established based on gluconate ion (Gluc) modified and 2-Naphthalenethiol (2-NT) tagged Au-Ag core-shell nanoparticles (NPs). Due to the complex formation between adsorbed Gluc and Pb²⁺, the addition of Pb²⁺ can induce the aggregation of Gluc/2-NT@Au@Ag NPs. Correspondingly, the aggregated Gluc/2-NT@Au@Ag NPs caused a significant difference in the color and SERS intensity. As a result, such Gluc/2-NT@Au@Ag NPs can achieve the sensing of Pb²⁺ using both colorimetric and SERS signals as the indicator, which features with wide response range from 10^-11 to 10^-5 M, rapid screening and high sensitivity (with a limit of detection (LOD) of 0.185 pM). Furthermore, such dual-mode sensor was demonstrated not to be responsive to other cations, and facilitate the sensing of real samples in practical environment. With rapid screening ability and outstanding sensitivity, we anticipate that this method would holding great potential for the applications in environmental monitoring.