Chiral recognition plays a vital role in chemical, biological, and pharmaceutical studies. However, differentiating enantiomers is still challenging. This study presents a new approach to enhance the distinction between enantiomers in surface-enhanced Raman scattering (SERS) by leveraging the coupling effect of propagating surface plasmon (PSP) and localized surface plasmons (LSP). We construct a SERS substrate that integrates laser-induced periodic surface structures with chiral plasmonic nanoparticle 432 helicoid III, creating a PSP-LSP coupling mechanism. The results demonstrate that the composite substrate not only enhances the SERS signal but also effectively amplifies the disparity between enantiomers. This advancement paves a new way in chiral SERS substrate design and the research of enantiomeric disparity amplification.
Surface-enhanced Raman scattering (SERS) has been widely investigated in recent years. The subtle design and synthesis of SERS substrates, including the semiconductor–metal composites, are the key but difficult points. To date, only the short-lived semiconductors are involved, and no research has been conducted concerning the long-lived ones although the persistent luminescence semiconductors have great potential of charge transfer in relatively long durations. Herein, we present a concept of afterglow-assistant SERS (AASERS) on the long-lived gold shell-capped Cr3+-doped ZnGa2O4 (CZGO@Au) substrate. The normal SERS, AASERS acquired immediately after 2 min illuminating of a 633 nm laser, AA-1 min SERS acquired 1 min after 2 min illuminating of a 633 nm of the typical analytes on CZGO@Au, ZnGa2O4@Au (ZGO@Au), and gold nanostars (GNSs) with the same UV–vis absorption wavelength are systematically compared. The CZGO@Au owns the SERS signals that are 1.8 times of ZGO@Au and 3.4 times of GNSs. A higher AASERS than the corresponding SERS (1.65 times) is only observed on CZGO@Au, and the AASERS on CZGO@Au is 2.8 times of that on ZGO@Au and 5.2 times of that on GNSs. Because of the afterglow decay of CZGO@Au, the AA-1 min SERS on CZGO@Au returns to its SERS. These data demonstrate that the AASERS on long-lived substrates is a promising way for further enhancing SERS signals just by laser illuminating the substrates, and thus affords alternatives for reducing the difficulties in the complicated synthesis of the exquisite substrates. The AASERS mechanism and the application of CZGO@Au in SERS imaging of living U87MG cells are also discussed.
Fluorescent gold (Au) nanostructures have emerged as burgeoning materials to fabricate nanomaterial assemblies which play a vital role in improving the detection sensitivity and specificity for various biomolecules. In this work, a fluorescence labelled (Rhodamine-B-Isothiocyanate) silica shell with Au metal core (AuNPs@PVP@RITC@SiO2) and a graphene–Au nanostar nanocomposite (rGO–AuNS) are presented as a metal enhanced fluorescence (MEF) material and Raman signal enhancer, respectively. Their composite (AuNPs@PVP@RITC@SiO2NPs/rGO–AuNS) was employed as a dual-mode fluorescence (FL) and surface-enhanced Raman scattering (SERS) nanoprobe for selective and sensitive detection of T-2 toxin. To comprehend the dual-modality, a core–shell nanostructure, AuNPs@PVP@RITC@SiO2, was functionalized with an aptamer (donor) and adsorbed on the surface of rGO–AuNS through electrostatic forces and π–π stacking which act as a FL quencher and SERS signal enhancer. When exposed to T-2 toxin, the apt-AuNPs@PVP@RITC@SiO2NPs move away from the surface of rGO–AuNS, resulting in the restoration of FL and reduction of the SERS signal. There was distinct linearity between the T-2 toxin concentration and the dual FL and SERS signals with lower limits of detection (LOD) of 85 pM and 12 pM, as compared to the previous methods, respectively. The developed FL and SERS aptasensor presented excellent recovery ratio and RSD in wheat and maize, respectively, as compared with the standard ELISA method. The complementary performances of the developed stratagem revealed a high correlation between the FL and SERS sensing modes with exquisite detection properties.
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