Metal-Enhanced Fluorescence: A paradigm shift in how we think and use Fluorescence Spectroscopy today
Dr. Chris D. Geddes
Institute of Fluorescence, University of Maryland Baltimore County, Columbus Center
In recent years the IoF has described the favorable interactions and outcomes of both plasmon supporting particles (Ag, Au, Cu, Zn, Ni, Cr) and substrates with electronically excited states. These favorable effects have included significantly enhanced fluorescence emission from singlet states, S1 and S21, as well as enhanced phosphorescence yields from triplet, T1, states (MEP) 2. In addition, we have observed and described plasmon enhanced chemiluminescence intensities (MEC), as well as highly directional emission. As a result of enhanced triplet yields, we have also observed both enhanced singlet oxygen and superoxide anion yields3.
These favorable influences on the photophysical properties of close proximity excited states to plasmon supporting substrates / particles has led to wealth of biochemical applications, such as the high sensitivity and ultra fast detection of proteins4, DNA5, RNA and ultra bright and photostable metal-enhanced fluorescence based particles for downstream cellular imaging applications. In addition, there are a lot downstream applications of MEP such as in photodynamic therapy by surface plasmon controlled single oxygen generation. Current thinking, describes Metal-Enhanced Fluorescence as the near-field coupling of electronic excited states to surface plasmons (a surface mirror dipole), the particle subsequently radiating the photophysical characteristics of the coupled excited state in the far-field, remarkably, even vibronic structure. In this presentation, we communicate our recent findings for metal-fluorophore interactions and our current thinking and progress towards developing a unified metal-fluorophore description.