Plasmonic Modulation of Gold Nanoplates on Multiwavelength Emission

Plasmonic regulation introduced by metallic nanoparticles is a useful method to improve the detection performance of plasmon-based systems. Herein, we observed a unique enhancement of surface plasmon-coupled emission (SPCE) using plate-shaped plasmonic nanostructures. By assembling Au nanoplates (Au NPLs) via electrostatic adsorption between the Au nanofilm and the quantum dot (QD) layer (630 nm), the fluorescence signal of SPCE was enhanced 90 times more than that of normal SPCE after the conditions were optimized. This enhancement was mainly induced by the intense localized electromagnetic field at the tip of Au NPLs and a novel plasmonic distribution around the "hot-spot" structure between the nanoparticle and Au nanofilm. These effectively mitigated the inherent signal quenching of SPCE and enhanced the emission signal of ultrathin samples on the surface of the NPL-modified Au nanofilm structure. This strategy can be used to improve the detection sensitivity and information integrity of SPCE-based biosensing and bioimaging systems containing ultrathin luminous layers. The different enhancement efficiencies for multiwavelengths were successfully obtained through various emission angles in light of the wavelength resolution of SPCE, thus verifying the existence and importance of energy-matching coupling, and the emission for the fluorophore with low excitation efficiency could also be detected. Benefiting from this, the Au NPL-modulated SPCE system could be a candidate for simultaneous multiwavelength enhancement and high-throughput detection in multicomponent analysis.