Fluorescence microscopy is a powerful analytical tool for the identification and investigation of biological components and processes. The extinction coefficient, quantum yield and fluorescence lifetime of the molecular probes traditionally used in imaging (i.e. fluorophores) all contribute to the utility of this technique. Metal-Enhanced Fluorescence (MEF) has great potential to overcome common problems in fluorescence microscopy, such as photobleaching or low quantum efficiency, by increasing fluorophore brightness, reducing their lifetimes, and improving photostability. MEF arises from near-field nano-molecular interactions between the electronic clouds of metal nanoparticles and fluorophores that enhance brightness by increasing either the rate of fluorophore excitation or the radiative decay rate, or both. Yet, practical applications of MEF in cell biology remains limited.<br/>In this work, we aimed to develop and optimize the use of silver nanoparticles (AgNP) for fluorescence imaging of cells in culture to improve fluorophore detection. We have performed fluorescence imaging with different configurations of AgNP and fluorophores (e.g. in solution or embedded within a complex matrix, such as gelatin). Our findings showed that the presence of AgNP significantly enhances fluorophore brightness in the gelatin matrix which can reliably mimic the complex spatial organization of a cell. Using AgNP, we then examined MEF of BODIPY-labelled molecules for imaging of specific organelles in living cells. We found that indeed AgNP displays MEF of BODIPY-labelled lysosomal markers in RAW 264.7 macrophages without appreciably impacting cellular function with improved signal-to-noise.

Application of metal-enhanced fluorescence for imaging of biological systems

ACS Spring Meeting 2021

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