Dynamically Metasurface-Modulated Electrochemiluminescence Polarization Coupling Angle Strategy for miR-142-3p Detection

Aggregation-induced ECL strategy based on CuAg nanoclusters/Curdlan-g-PGTMAC for gastric cancer detection

In this work, a novel biosensor based on aggregation-induced luminescence (AIE) of copper-silver alloy nanoclusters (CuAg NCs) has been developed for the detection of gastric cancer marker miRNA-142-3p. The alloy nanoclusters were synthesized by doping Ag ions into Cu NCs as nano-emitters. On the one hand, the doped Ag ions induced Ag-Cu metallophilic interactions, which promoted the relaxation of excited electrons through the radiative pathway. On the other hand, the doped Ag ions can reduce the band gap between the HOMO-LUMO orbitals of the nanoclusters, which decreased the energy consumed for electronic excitation. Therefore, the luminescent signal and stability of CuAg NCs were significantly enhanced. Furthermore, the modification of the permanently positively charged polysaccharide quaternary ammonium salt (Curdlan-g-PGTMAC) on CuAg NCs induced the aggregation-induced electrochemiluminescence (AIECL) effect. The introduction of Curdlan-g-PGTMAC also accelerated the reduction of the co-interaction reagent (S2O82-), which significantly improved the ECL generation efficiency. The ECL response of the CuAg NC-based AIECL biosensor showed a good linear correlation with the concentration of miRNA-142-3p over a wide range from 1 fM to 100 nM with a detection limit as low as 8.8 fM. The ECL biosensor with high sensitivity and wide dynamic range was used for the clinical application of miRNA-142-3p in gastric cancer successfully.

Magnetoplasmonic Metasurface-Modulated Electrochemiluminescence Strategy for Extracellular Vesicle Detection

Due to the ideal optical manipulation ability, the metasurface has broad prospects in the development of novel optical research. In particular, an active metasurface can control optical response through external stimulus, which has attracted great research interest. However, achieving effective modulation of the optical response is a significant challenge. In this work, we have developed a novel electrochemiluminescence (ECL) signal modulation strategy by an active magnetoplasmonic metasurface under an external magnetic field. The magnetoplasmonic metasurface was assembled based on yolk-shell Fe3O4@Au nanoparticles (Fe3O4@Au YS-NPs). On the one hand, the yolk-shell structure of Fe3O4@Au YS-NPs possessed the surface plasmon coupling effect and cavity-based Purcell effect, which provided high-intensity electromagnetic hot spots in the magnetoplasmonic metasurface. On the other hand, due to the strong magnetic response of the Fe3O4 core, the local magnetic field was induced by the external magnetic field, which further generated Lorentz force acting on the free electrons of Au nanoshells with strong optical anisotropy. The plasmon frequency of the metasurface can be effectively modulated by the Lorentz force effect. As a result, the ECL signal of nitrogen dots (N dots) was dynamically modulated and significantly enhanced at a specific polarization angle by the magnetoplasmonic metasurface under the variable external magnetic field. Based on the luminescence modulation ability and structure feature, the magnetoplasmonic metasurface was further established successfully as a sensing interface for gastric cancer (GC) extracellular vesicle (EV) detection. This study illustrated that the electromagnetic response of the active metasurface can effectively improve the optical modulation ability and luminescence sensing performance.