Non-fluorescent schemes for single-molecule detection, imaging and spectroscopy

Abstract

The detection and study of single molecules with light has for decades relied on fluorescence-based detection. The development of other optical forms of singlemolecule interrogation would, however, greatly expand the range of addressable molecules beyond those species that are highly emissive and photostable, and offer new applications beyond molecular biophysics and imaging. Here, we review the range of recent developments in optical label-free detection and imaging schemes that offer single molecule sensitivity, with an emphasis on plasmonic-enhanced and scattering approaches. We highlight the advantages and challenges facing these emerging methodologies and briefly outline their potential future applications..

Exciton Transport in Molecular Aggregates – From Natural Antennas to Synthetic Chromophore Systems

“…Although several detection schemes based on direct absorption or stimulated emission measurements were successfully demonstrated, they can still not be generally applied to a variety of systems. [103] As outlined in Section 3.1 to date the best signal-to-noise and signal-to-background ratios for the detection of single molecules is achieved by recording their (incoherent) fluorescence signal using confocal microscopy. However, fluorescence is a rather "slow" process, with typical excited-state lifetimes on the order of 1 ns for organic systems.…”

Single-Molecule Investigation of Energy Dynamics in a Coupled Plasmon-Exciton System

“…This is not the case for absorption spectroscopy [1][2][3][4] which is the primary technique to directly investigate the excitation process. Because absorbance is measured as attenuation of the incident light at a given frequency, the absorption signal competes with the huge shot-noise of the incident photons 13 .…”

Interferometric Scattering Microscopy for the Study of Molecular Motors

“…As a result, the relevant single-molecule assays are in many instances easier to implement as they require fewer labeling steps. Most importantly, however, iSCAT provides access to experimental approaches and timescales that are inaccessible to single-molecule fluorescence-based studies, either due to the underlying photophysics or due to the difficulty associated with removing fluorescence background (Arroyo & Kukura, 2016; Ortega-Arroyo & Kukura, 2012). …”