Plasmonic Hybrid Nanocomposites for Plasmon-Enhanced Fluorescence and Their Biomedical Applications

Abstract

Fluorescence is a powerful tool in biochemistry, biophysics, forensic science, and biotechnology. Two main principal properties for any fluorophore, brightness and photostability, are fundamentally important to achieve a high level of sensitivity for detection. Therefore, improvements in the technique are strongly encouraged and pursued, such as new developments in terms of the technique sensitivity, the range of fluorophores, their stability, and the versatility of the experimental setups that help move this particular scientific research in biosensing and molecular imaging forward. Therefore, a new avenue is based on the use of plasmonic nanostructures in the enhancement of the collective photo-physical properties including their absorption and fluorescence, known as "plasmon-enhanced fluorescence." Such plasmonic enhancement is due to the localized surface plasmon resonance at the metal surface, which leads to increasing the exciton radiative recombination rate in the fluorophore and thereby improves the signal obtained and increases sensitivity. In addition, the plasmonic enhancement might depend on several parameters such as nanoparticle size and shape, metal type, and the spectral overlap in the absorption spectra and the type and the separation distance between both plasmonic nanoparticle and the fluorophore. Throughout this chapter, previous approaches are discussed, which are devoted to tracking the influence of plasmonic nanostructures on the photoluminescence of the fluorophores especially the hybrid nanocomposites based on plasmonic/quantum dots including semiconductor and carbon-based nanoparticles. In addition, the possible applications of metal-enhanced fluorescence nanohybrids in the biological and medical applications such as imaging and biosensing techniques.