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

点击翻译按钮获取中文摘要

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.**