Metal Enhanced Fluorescence: Effect of surface coating

摘要

Metal Enhanced Fluorescence (MEF), a phenomenon arising when a fluorophore is in closed proximity to a metallic structure such as metallic films or nanostructures, is seen as a way to increase the amount of reactive oxygen species produced by the irradiation of the protoporphyrin Ⅸ (PpⅨ), a photosensitizer commonly used in photodynamic therapy. Here, we show a study of the distance-dependent of MEF by applying multiple layers of polyelectrolyte (PE) on silver nanoparticles (AgNPs) to progressively increase the distance between AgNPs and PpⅨ, covalently bond to the last polyelectrolyte layer as well as exploring the use of AgNPs of different sizes ranging from 40 to 100 nm. Up to four fold increase of PpⅨ fluorescence was observed when this photosensitizing agent is bounded onto 100 nm sized Ag NPs. The effective corresponding distance between AgNPs and PpⅨ is three layers of PE.