Surface Plasmon-Enhanced Fluorescence Spectroscopy on Silver Based SPR Substrates

Abstract

For sensitive surface plasmon resonance (SPR) sensing the choice of the metal film and the strategy to bind the receptors to the SPR chip is critical. We have shown recently (Touahir, L.; Niedziolka-Jonsson, J.; Galpin, E.; Boukherroub, R.; Gouget-Laemmel, A. C.; Solomon, I.; Petukhov, M.; Chazalviel, J.-N.; Ozanam, F.; Szunerits, S. Langmuir 2010, 26, 6058) that a 5 nm thick layer of an amorphous silicon−carbon alloy (a-Si1−x C x :H) deposited on a silver-based SPR interface can significantly enhance the sensitivity. In addition, the capping of a surface-plasmon active silver layer with a thin film of hydrogenated amorphous silicon−carbon alloy provides a practical solution for obtaining chemically stable SPR interfaces usable in conditions typical of bioassays with the additional advantage of benefiting from well-controlled processes for a robust covalent immobilization of biological probes to the interface. In this paper we demonstrate that the developed architecture in conjugation with an optimized surface functionalization scheme allows for a highly sensitive analysis of interfacial DNA−DNA binding interactions using surface plasmon-enhanced fluorescence (SPFS) as detection principle. The influence of the density of surface linked DNA probes on the recognition of 50 nM cDNA strands is presented. On an optimized surface (15% of acid-anchoring groups) DNA complementary probes with concentrations of 500 fM could be detected making this approach interesting compared to classical SPR experiments where nanomolar (nM) detection limits are conventionally reached.

A Novel Approach of Synthesizing and Evaluating the Anticancer Potential of Silver Oxide Nanoparticles in vitro

“…This increment of fluorescence intensity was found to increase in a temporal manner. Various reports have disclosed that silver NPs exhibit surface plasmon resonance, so we assume that the underlying cause of the marked fluorescence patterns under FL1 and FL2 filters by AgONPs is due to this phenomenon of surface plasmon resonance [21,22,23]. …”

Reflectivity optimization of the SPR graphene sensor

“…When compared with gold, the plasmon coupling in the silver has a sharper angular resonance peak [12], but it presents a drawback that it can be easily oxidized and the poor chemical stability thus affecting the performance of SPR-sensors [11,12]. Many of methods were designed in an attempt to overcome this problem, for example the use of bimetallic silver-gold layers [13,14], a thin oxide fi lms TiO 2 or SnO 2 [15][16][17], In addition to thin fi lms of carbon such as the amorphous carbon [18], amorphous carbonated silicon (a-Si 0.63 C 0.37 ) [19][20][21] and the newer one is, graphene [13].…”

Selectable Surface and Bulk Fluorescence Imaging with Plasmon-Coupled Waveguides

“…Surface plasmon-enhanced fluorescence (SPEF) uses the enhanced field for increased excitation intensities near the metal surface, but only the free-space emission is detected. 22, 23 Surface plasmon-coupled emission (SPCE) uses both the enhanced surface-plasmon field and near-field coupling of fluorescence to the metal film. 24, 25 In SPCE the observed signal is selective for the surface-coupled emission, but does not provide a separate measurement of the bulk emission.…”