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Surface plasmona??coupled emission imaging for biological applications
摘要： Fluorescence imaging technology has been extensively applied in chemical and biological research profiting from its high sensitivity and specificity. Much attention has been devoted to breaking the light diffraction–limited spatial resolution. However, it remains a great challenge to improve the axial resolution in a way that is accessible in general laboratories. Surface plasmon–coupled emission (SPCE), generated by the interactions between surface plasmons and excited fluorophores in close vicinity of the thin metal film, offers an opportunity for optical imaging with potential application in analysis of molecular and biological systems. Benefiting from the highly directional and distance-dependent properties, SPCE imaging (SPCEi) has displayed excellent performance in bioimaging with improved sensitivity and axial confinement. Herein, we give a brief overview of the development of SPCEi. We describe the unique optical characteristics and constructions of SPCEi systems and highlight recent advances in the use of SPCEi for biological applications. We hope this review provides readers with both the insights and future prospects of SPCEi as a new promising imaging platform for potentially widespread applications in biological research and medical diagnostics.
关键词： Fluorescence microscopy,Directional emission,Background suppression,Surface plasmon–coupled emission imaging,Biological application,Cell imaging
更新于2025-09-23 15:19:57
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Excitation-Emission Synchronization Mediated Directional Fluorescence: Insight into Plasmon Coupled Emission at the Vibrational Resolution
摘要： Light-matter interaction is always the fundamentally significant topic to attract much attentions. It is important to reveal fluorophore-plasmon interaction at the nanoscale. Although as a powerful investigative tool, fluorescence spectroscopy still suffers from the limited spectral resolution and its susceptibility to interfering substances. In this work, the excitation-emission synchronization mediated surface plasmon coupled emission (EES-SPCE) is proposed to break the bottleneck. By actively screening the energy transitions for observation, the improved spectral resolution has been achieved, which is advantageous to the investigation of the fluorophore-plasmon interactions under different coupling modes. The spectral information related to the plasmonic interactions through tuning vibrational energy levels are clearly distinguished at directional emission angles. EES-SPCE is demonstrated to selectively and efficiently extract the coupled emission with the vibrational resolution, which would open up the opportunities to improve the capability of spectral feature identification and signal collection for practical applications of plasmonic fluorescence spectroscopy.
关键词： synchronous fluorescence spectroscopy,energy difference,directional emission,surface plasmon coupled emission,spectral resolution
更新于2025-09-23 15:19:57
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Silver Soret Nanoparticles for Femtomolar Sensing of Glutathione in a Surface Plasmon-Coupled Emission Platform
摘要： Surface plasmon-coupled emission (SPCE) has emerged as an interdisciplinary, versatile sensing platform due to its highly directional, solid-state and polarized emission. Here, we report the distinct properties rendered by Ag-Soret Colloids (Ag-SCs) such as nanovoids and nanocavities to observe 104-fold enhancement in emission intensity of omnidirectionally radiating emitter dipoles. Unlike earlier reports utilizing templated Ag-nanoparticles in spacer or cavity architectures, here we employ template-free, linker-less Ag-SCs. Purcell factor (PF - maximum of 120.6) obtained using the finite-difference time-domain (FDTD) simulations for soret nanocavities are in excellent agreement with the trend in emission enhancements obtained experimentally. Thermal gradient created by adiabatic cooling of Ag nanoparticles (AgNPs) drives their thermo-diffusion resulting in monodisperse nanoparticle assemblies (Ag-SCs). In addition, we report an extended-cavity architecture with Ag-SCs, as a novel pseudo-metal-dielectric-metal (p-MDM) interface, for achieving 80-fold SPCE. This study also features the unique properties of Ag-SCs as interfacial nanomaterials in SPCE platform to achieve femtomolar detection of glutathione (GSH). The quenching of fluorescence from alizarin red S-boric acid (ARS-BA) complex upon addition of Cu2+ ions and the dequenching upon GSH addition studied with Ag-SCs as spacer layer remarkably increased the sensitivity of the analyte. The uniform and intense electromagnetic field-confinement provided by these intricate architectures and hybrid interfaces, along with its ease of fabrication and versatility for variety of analytes, is critical to achieve augmented SPCE. This is accomplished without compromising on the reliability of detection as demonstrated with the use of a cellphone camera, CIE color space and luminosity plots for the turn-on fluorescence. The emission images were acquired using an android phone camera by aligning it with its angular emission, making it amenable for point-of-care diagnostics.
关键词： Soret colloids,Surface plasmon-coupled emission,spacer engineering,smartphone-based detection,template-free approach,fluorescence enhancement,glutathione sensing
更新于2025-09-23 15:19:57
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Femtomolar Detection of Spermidine using Au Decorated SiO <sub/>2</sub> Nanohybrid on Plasmon-Coupled Extended Cavity Nanointerface: A Smartphone based Fluorescence Dequenching approach
摘要： Coupling of photons with molecular emitters in different nanocavities have resulted in transformative plasmonic applications. The rapidly expanding field of surface plasmon-coupled emission (SPCE) has synergistically employed subwavelength optical properties of localized surface plasmon resonance (LSPR) supported by nanoparticles (NPs) and propagating surface plasmon polaritons assisted by metal thin films for diagnostic and point-of-care analysis. Gold nanoparticles (AuNPs) significantly quench the molecular emission from fluorescent molecules (at close distances < 5 nm). More often, complex strategies are employed for providing a spacer layer around the AuNPs to avoid direct contact with fluorescent molecules, thereby preventing quenching. In this study we demonstrate a rapid and facile strategy with the use of Au-decorated SiO2 NPs (AuSil), a metal (Au)-dielectric (SiO2) hybrid material for dequenching the otherwise quenched fluorescence emission from radiating dipoles and to realize 88-fold enhancement using the SPCE platform. Different loading of AuNPs were studied to tailor fluorescence emission enhancements in spacer, cavity and extended (ext.) cavity nanointerfaces. We also present femtomolar detection of spermidine using this nanohybrid in a highly desirable ext. cavity interface. This interface serves as an efficient coupling configuration with dual benefits of spacer and cavity architectures that has been widely explored hitherto. The multifold hot-spots rendered by the AuSil nanohybrids assist in augmented electromagnetic (EM)-field intensity that can be captured using a smartphone based SPCE platform presenting excellent reliability and reproducibility in spermidine detection.
关键词： fluorescence enhancements,extended cavity nanointerface,Au-decorated SiO2 NPs (AuSil),dequenching,surface plasmon-coupled emission
更新于2025-09-19 17:13:59
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Enhanced modulation of magnetic field on surface plasmon coupled emission (SPCE) by magnetic nanoparticles
摘要： The obvious enhancement effect of magnetic nanoparticles (MNPs) introduced in Cr/Co/Cr/Au substrate on the pulsed magnetic field-modulated surface plasmon coupled emission (SPCE) was investigated, and the observed enhancement factor was 4 comparing with the magnetic field modulated SPCE without MNPs. This is the new observation for the magnetic field-modulated SPCE in fluorescence signal and helps to build the new SPCE based stimulus-response system.
关键词： Magnetic field modulation,Magnetic nanoparticle,Surface plasmon coupled emission (SPCE),Fluorescence enhancement,Biosensor
更新于2025-09-16 10:30:52
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Far-field radiation of three-dimensional plasmonic gold tapers near apices
摘要： Three-dimensional plasmonic gold tapers are widely used structures in nano-optics for achieving imaging at the nanometer-scale, enhanced spectroscopy, confined light sources, and ultrafast photoelectron emission. To understand their radiation properties further, especially in the proximity of the apex at the nanoscale, we employ cathodoluminescence spectroscopy with high spatial and energy resolution. The plasmon-induced radiation in the visible spectral range from three-dimensional gold tapers with opening angles of 13° and 47° is investigated under local electron excitation. We observe a much weaker radiation from the apex of the 13° taper than from that of the 47° taper. By means of finite-difference time-domain simulations we show that for small opening angles plasmon modes that are created at the apex are efficiently guided along the taper shaft. In contrast for tapers with larger opening angles, generated plasmon polaritons experience larger radiation damping. Interestingly, we find for both tapers that the most intense radiation comes from locations a few hundreds of nanometers behind the apices, instead of exactly at the apices. Our findings provide useful details for the design of plasmonic gold tapers as confined light sources or light absorbers.
关键词： plasmonics,surface plasmon coupled emission,cathodoluminescence,gold taper
更新于2025-09-12 10:27:22