Plasmonic core-shell luminescent nanoparticles: A self-supporting sensing platform

金属纳米颗粒内电磁场的限制是被称为局部表面等离子体共振（LSPR）的光学现象的起源。这种限制与局部场强的大幅增强有关，这反过来又导致靠近金属表面放置的荧光物质的量子产率和辐射率显着增加。此外，人们可以利用LSPR频率对金属纳米颗粒的组成、几何形状、尺寸和介电环境的依赖性来设计能够在从UV到近红外（NIR）的光谱范围内增强荧光团的发射强度的最佳纳米结构。* 自猝灭（即相邻荧光团之间发生的信号损失）的显著减少和检测灵敏度和光稳定性的增强可以用由多层二氧化硅涂覆的纳米尺寸的银核组成的核-壳纳米颗粒获得。通过仔细控制核心和同心层中排列的荧光团之间的间距，这些纳米结构可用于增强福斯特共振能量转移（FRET）效率和位于这些多层复合纳米颗粒上的供体-受体对之间的范围。我们最近展示了这些纳米探针作为弱荧光分析物的等离子体增强剂的用途，用于痕量水平的特定基因的定量检测以及细胞膜附近生理离子的光稳定成像。这些多层核-壳纳米颗粒具有理想的自支撑传感平台所需的许多特征：它们提供高光学检测灵敏度，优异的化学和物理稳定性，在水中的高分散性，以及容易的表面功能化。此外，它们的流动性是探测生物传感应用中扩展样品体积的内容物或功能性细胞成像工作的资产。在本研究计划中，我们将设计新型多层核壳荧光纳米结构，最大限度地提高发光和FRET的等离子体增强，研究其物理特性，并将其发展为分子传感纳米结构，用于痕量基因，生物标志物，毒素，病原体，肿瘤细胞等的灵敏检测以及分析化学，材料科学，等离子体，光子学和生物技术 **

The confinement of electromagnetic fields within metallic nanoparticles is at the origin of the optical phenomenon known as localized surface plasmon resonance (LSPR). This confinement is associated with large enhancements in local field intensity, which lead in turn to significant increases in the quantum yield and radiative rates of fluorescent species placed close to the metal surface. Furthermore, one can take advantage of the LSPR frequency's dependence on the composition, geometry, size and dielectric environment of metallic nanoparticles to design optimal nanostructures able to enhance the emission intensity of fluorophores across the spectrum from UV to the near infrared (NIR). ***A significant reduction of self-quenching (i.e. signal losses occurring between neighboring fluorophores) and an  enhancement of detection sensitivity and photostability can be obtained with core-shell nanoparticles composed of a nanometer-size silver core coated by multiple layers of silica. By careful control of the spacing between the core and fluorophores arranged in concentric layers, these nanostructures can be used to enhance Förster resonant energy transfer (FRET) efficiency and range between donor-acceptor pairs localized on these multilayer composite NPs. We recently demonstrated the use of these nanoprobes as plasmonic enhancers for weakly fluorescent analytes, for the quantitative detection of specific genes at the trace level and for photostable imaging of physiological ions near cellular membranes.****These multilayer core-shell nanoparticles present many of the features required of an ideal self-supported sensing platform: they offer high optical detection sensitivity, excellent chemical and photophysical stability, high dispersability in water, and facile surface functionalization. Furthermore, their mobility is an asset for probing the contents of extended sample volumes in biosensing applications or for functional cell imaging work. In this research program, we will design novel multilayer core-shell fluorescent nanoarchitectures that maximize plasmonic enhancement of luminescence and FRET, investigate their photophysical characteristics, and develop them into molecular sensing nanostructures for the sensitive detection of trace amounts of genes, biomarkers, toxins, pathogens, tumor cells, etc. and other applications in the fields of analytical chemistry, materials science, plasmonics, photonics and biotechnology.**