Magnetron-Sputtered Polytetrafluoroethylene-Stabilized Silver Nanoisland Surface for Surface-Enhanced Fluorescence

Abstract

Surface-enhanced fluorescence (SEF) requires the absorption/emission band of the fluorophore, the localized surface plasmon resonance (LSPR) of the nanostructure and the excitation wavelength to fall in the same (or very close) spectral range. In this paper, we monitor the SEF intensity and lifetime dependence of riboflavin (vitamin B2) adsorbed on a spacer-modified Ag substrate with respect to the thickness of the spacer. The substrates were formed by silver nanoislands deposited onto magnetron-sputtered polytetrafluoroethylene (ms-PTFE). The spacer was formed by the ms-PTFE layer with the thickness ranging from ~5 to 25 nm. The riboflavin dissolved in dimethylsulfoxide (DMSO) at a 10 µM concentration forms, at the ms-PTFE surface, a homogeneous layer of adsorbed molecules corresponding to a monomolecular layer. The microspectroscopic measurements of the adsorbed layer were performed through a sessile droplet; our study has shown the advantages and limitations of this approach. Time-resolved fluorescence enabled us to determine the enhanced fluorescence quantum yield due to the shortening of the radiative decay in the vicinity of the plasmonic surface. For the 5 nm ms-PTFE layer possessing the largest (estimated 4×) fluorescence enhancement, the quantum yield was increased 2.3×.

Evaluation of Steady-State and Time-Resolved Fluorescence Spectroscopy as a Method for Assessing the Impact of Photo-Oxidation on Refined Soybean Oils

“…This excitation/emission region (500/550 nm) can be related to riboflavins (vitamin B-derived), and carotenoids, highly oxidizable compounds naturally present in vegetable oils [48,50,51]. The red bottle used in this study offers greater protection from light in the absorption region around 500 nm compared to the others (Figure S1), which may be responsible for reducing its degradation during light exposure.…”

The proof of the pudding is in the bleaching … oder so ähnlich

“…Riboflavin zeigt bei 445 nm ein relatives Absorptionsmaximum und emittiert maximal bei ca. 550 nm [11], was im Spektrum im Übergang von gelb zu grün liegt. Wird das farbgebende π‐System unterbrochen, beispielsweise durch Angriff eines starken Reduktons, verschwindet die Farbe.…”

Dual-Mode Detection of Cysteamine Using Ag Nanoparticle-Riboflavin Composites

“…It was further successfully used to specifically detect the content of RF in human urine . Subr et al deposited silver nano islands on the surface of polytetrafluoroethylene by magnetron sputtering for surface-enhanced fluorescence of RF, and a maximum fluorescence enhancement of 4-fold was obtained . In addition, the molecular structure of Cys has a good affinity for many plasmonic nanoparticles, which leads to the aggregation of plasmonic nanoparticles and induces fluorescence restoration.…”