The utilization of metallic nanostructures is a promising means of improving the efficiency of photochemical and photophysical processes of organic fluorophores. For instance, near-field interactions between chromophores and the electron clouds present in metal colloids can augment the photophysical processes responsible for far-field emission through Metal-Enhanced Fluorescence (MEF). Indeed, metal nanoparticle surfaces can respond to the oscillating dipole of radiating fluorophores by effectively modifying the rates of excitation and emission, ultimately improving brightness. From an application perspective, MEF offers a versatile means of engineering increased fluorescence intensity and facilitating fluorescence activation for patterning, fluorescence imaging and single molecule bioassays. This contribution will discuss the use of single molecule fluorescence microscopy to examine the MEF mechanism in a system of triangular silver nanoparticles (AgNPs) and a fluorogenic boron dipyrromethene (BODIPY) that can be activated by UVA light in the presence of an appropriate photoacid generator. Though indistinguishable at the ensemble level, distinct mechanistic components of MEF become apparent in the single molecule regime, leading to actionable insights into the nano-molecular interactions responsible AgNP-induced enhancement of fluorescence intensity and activation. This work also expands the utility of MEF by providing experimental evidence that MEF can be accessed through indirect plasmonic excitation by excited-state fluorophores. Linking single molecule behaviour with bench-scale observations affords the opportunity to better understand, and ultimately improve, the exploitation of photophysical and photochemical phenomena associated with nano-molecular interactions.

Mechanistic insights into metal-enhanced fluorescence by triangular silver nanoparticles at the single molecule level

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.