Plasmonic Nanozyme-Driven Chemiluminescence, Temperature, and RGB Multimodal Sensing for Reliable Discrimination of Enantiomers

Multimodal probes can output multidimensional signals and meet the demand for discriminating highly similar enantiomers. Their diverse signal transducing mechanisms broaden the discrimination scope of enantiomers and ensure adaptability in various application scenarios. Herein, an achiral multimodal probe termed gold-cobalt nanoparticles (AuCoNPs) was synthesized, which showed outstanding enantioselectivity, Fenton-like activity, and localized surface plasmon resonance effects. It promoted the chemiluminescent (CL) signal of the luminol system and exhibited color and temperature (TP) response characteristics. The assay platform based on a multimodal probe can discriminate 11 kinds of enantiomers, showing an enantioselectivity of 4.29 for glutamic acid (Glu). For the CL mode, the stronger binding affinity of l-Glu to AuCoNPs reduced its adsorption onto the poly(vinyl alcohol)/sodium alginate hydrogel, resulting in a weaker CL signal compared to d-Glu. For the RGB mode, the aggregation state of AuCoNPs was affected by the affinity of Glu enantiomers to the probe, creating a distinguishable color gradient. This enables rapid visual discrimination for Glu enantiomers using smartphone RGB imaging within 3 min. For the TP mode, the aggregation state affected the photothermal conversion, producing different TP changes induced by the enantiomers. Density functional theory calculations, contact angle measurements, and zeta potential measurements were used to explore the discrimination mechanism. The multimodal probe shows promising practicality for chiral discrimination due to the combinational usage of multidimensional signals.