Mapping the Fluorescence Performance of a Photochromic–Fluorescent System Coupled with Gold Nanoparticles at the Single-Molecule–Single-Particle Level

Abstract

Single-molecule (SM) fluorescence microscopy was used to investigate the photochromic fluorescent system spiropyran-merocyanine (SP ↔ MC) interacting with gold nanoparticles (AuNPs). We observe a significant increase in the brightness of the emissive MC form, in the duration of its ON time, and in the total number of emitted photons. The spatial distribution of SMs with improved photophysical performance was obtained with 40 nm precision relative to the nearest AuNP. We demonstrate that even photochromic systems with poor photochemical performance for SM can become suitable for long time monitoring and high performance microscopy by interaction with metallic NP.

Super-resolution microscopy as a powerful tool to study complex synthetic materials

“…97 Profiting from this opportunity, Uji-i and coworkers imaged fluorescently tagged proteins on plasmonic nanowires 98 . Aramendía and co-workers used a similar two-laser activation strategy to convert spiropyran into its fluorescent merocyanine form on gold nanorods 99 . The optimal dye-metal distance is short enough to promote fluorescence enhancement and long enough to limit fluorescence quenching.…”

Shifting molecular localization by plasmonic coupling in a single-molecule mirage

“…Recently, several studies have applied localization based fluorescence nanoscopy near plasmonic nanostructures aiming to reveal nanometric details about optical near fields161719, nanoparticle geometry2021, surface chemistry22 and electromagnetic interactions with nearby molecules23. Interestingly, this seemingly straightforward approach does not always deliver accurate information of dye positions and electric field intensity distributions due to coupling of the emitters to localized surface plasmon resonance modes of the nanostructures.…”

Two‐Photon Excitation of a Plasmonic Nanoswitch Monitored by Single‐Molecule Fluorescence Microscopy

“…A solution of 1 a in poly(methyl methacrylate) was then spin‐coated atop the functionalized slides in order to obtain polymer films approximately 100 nm thick. The construction and the preparation of the sample ensures that molecules dispersed atop the AgNP monolayer will be in close proximity to the enhanced field produced by excitation of the localized surface plasmon of AgNP, with the gaps between the densely packed nanostructures filled by polymer . With full coverage of the slide with AgNP and a polymer film 100 nm thick, the enhanced field is expected to cover roughly 20 % of the sample .…”

“…The construction and the preparation of the sample ensures that molecules dispersed atop the AgNP monolayer will be in close proximity to the enhanced field produced by excitation of the localizeds urface plasmon of AgNP,w ith the gaps betweent he densely packed nanostructures filled by polymer. [13] With full coverage of the slide with AgNP and ap olymer film 100 nm thick, the enhanced field is expected to cover roughly2 0% of the sample. [14] This ensures that most molecules of 1a will be sufficiently close to AgNP and within the field enhancement region.Afractiono ft he small population of 1b in thermal equilibrium with 1a will experiencef ield enhancement.…”