Optimizing silver film for surface plasmon-coupled emission induced two-photon excited fluorescence imaging

Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan.
Optics Express (Impact Factor: 3.49). 03/2011; 19(6):5386-96. DOI: 10.1364/OE.19.005386
Source: PubMed


In this study, the optimal condition of a silver (Ag) film deposited on a cover slip for surface plasmon-coupled emission (SPCE) induced two-photon excited fluorescence (TPEF) based on an objective-based, total internal reflection (TIR) microscope was investigated. According to the theoretical simulations of local electric field enhancement and fluorescence coupled emission efficiency, the thickness of the Ag film should be about 40 nm in order to maximize the TPEF collection efficiency by the objective. The deposited Ag film with a germanium seed layer on a cover slip exhibits additional improvement in surface smoothness by reducing variations in surface roughness to below 1.0 nm, thereby reduces local hot spots which degrade the image uniformity. Moreover, an Ag film with a 20 nm-thick SiO2 spacer not only prevents damage caused through interaction with the aqueous solution under high laser power irradiance, but also reduces the fluorescence quenching effect by the Ag film. By optimizing the Ag film thickness, surface smoothness, and a protective dielectric spacer, efficient TIR TPEF imaging can be achieved through SPCE.

8 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Surface plasmon-coupled emission (SPCE) arose from the integration of fluorescence and plasmonics, two rapidly expanding research fields. SPCE is revealing novel phenomena and has potential applications in bioanalysis, medical diagnostics, drug discovery, and genomics. In SPCE, excited fluorophores couple with surface plasmons on a continuous thin metal film; plasmophores radiate into a higher-refractive index medium with a narrow angular distribution. Because of the directional emission, the sensitivity of this technique can be greatly improved with high collection efficiency. This review describes the unique features of SPCE. In particular, we focus on recent advances in SPCE-based analytical platforms and their applications in DNA sensing and the detection of other biomolecules and chemicals.
    Annual Review of Analytical Chemistry (2008) 04/2012; 5(1):317-36. DOI:10.1146/annurev-anchem-062011-143208 · 8.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate that pulse shaping of a broadband Ti:sapphire laser can result in almost an order of magnitude increase in the sensitivity and signal to background ratio (SBR) of multiphoton total internal reflection fluorescence (TIRF) microscopy. We produced transform-limited pulses of 15 fs duration at the sample, and observed a 8-fold enhancement in the fluorescence of CdSe/ZnS quantum dots via two-photon objective-type TIRF excitation. There was a concomitant 6-fold increase of the SBR upon compression of the pulse duration. Enhancement of non-linear evanescent imaging has recently been demonstrated using surface-plasmons [Opt. Express 17, 5987 (2009)] and structured substrates [Opt. Express 18, 23218 (2010)]. Our approach of ultrafast pulse shaping could be used alone or combined with these new methods to offer significant gains in image quality.
    Optics Express 11/2012; 20(23):25948-59. DOI:10.1364/OE.20.025948 · 3.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: AbstractA prism‐based surface plasmon coupled emission (SPCE) imaging apparatus with a reverse Kretschmann (RK) configuration was developed and applied to dye‐doped polymer films. Highly polarized, directional and enhanced fluorescence images were obtained. The angular distribution of the SPCE images was in accordance with the validated theoretical calculation performed using Fresnel equation. Prism‐based SPCE imaging combined with microarray technology appears to be a promising platform for rapid and high‐throughput analysis, especially for high‐density arrays. We believe that prism‐based SPCE imaging has potential applications in biochemical research.
    ChemPhysChem 12/2012; 13(17). DOI:10.1002/cphc.201200569 · 3.42 Impact Factor
Show more