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Enhanced two-photon fluorescence excitation by resonant grating waveguide structures

ICFO--Insitut de Ciències Fotòniques and Universitat Politècnica de Catalunya, 08034 Barcelona, Spain.
Optics Letters (Impact Factor: 3.18). 10/2004; 29(17):1989-91. DOI: 10.1364/OL.29.001989
Source: PubMed

ABSTRACT Enhanced two-photon fluorescence (TPF) spectroscopy with novel high-finesse resonant polymeric grating waveguide structures (GWSs) is presented. Under resonant conditions the field enhancement at the surface of a GWS can be exploited for TPF spectroscopy without the need for highly focused laser excitation light. We compare the TPF obtained by placing a drop of tetramethylrhodamine (TMR) on top of a GWS with that obtained with TMR on top of a glass substrate. Our procedure and results indicate that the detection of TPF can be improved by a factor of 10 with resonant GWSs.

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    • "Currently, due to the high photon density required for TPF excitation, the efforts are focused on developing enhancement platforms in order to avoid tight focusing of ultrashort pulsed lasers [23]. Among such platforms we can find planar waveguides [20], photonic crystal fibers [24], grating waveguide structures (GWS) [21] [22] and double grating waveguide structures (DGWS) [23]. The DGWS are multilayered structures (two gratings and a thin waveguide layer) that show an abnormal reflection [25] due to the destructive interference between the diffracted and the directly transmitted wave when a guided mode is excited in the waveguide. "
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    ABSTRACT: An immunosensor approach based on non-linear two-photon fluorescence spectroscopy (TPF) coupled to a resonant double grating waveguide structure (DGWS) has been used for the detection of methylboldenone (MB), an androgenic anabolic steroid used illegally as growth promoter. This synthetic steroid is detected by the biosensor down to 0.1 μg l−1, two orders of magnitude lower than the minimum required performance limit (MRPL) required by the World Anti-Doping Agency (WADA). Nevertheless, we have focused this work on the synthesis and characterization of small fluorescent-labeled conjugates, as well as on the modification of the waveguide surfaces. Detection relies on a direct competitive format, using a boldenone–rhodamine conjugate as fluorescent competitor and a specific anti-MB antibody. The immunoreagents are immobilized onto a resonant Ta2O5 sensing chip after being activated with phosphonohexanoic acid spacers, a novel methodology for covalently surface immobilization of biomolecules, which shows better stability and homogeneity than classical silane chemistries. The developed immunosensor presents great potential as a robust device for its implementation on the detection of small illegal and toxic contaminants.
    Sensors and Actuators B Chemical 11/2012; 174:394. DOI:10.1016/j.snb.2012.08.006 · 4.29 Impact Factor
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    • "Currently, due to the high photon density required for TPF excitation, the efforts are focused on developing enhancement platforms in order to avoid tight focusing of ultrashort pulsed lasers [23]. Among such platforms we can find planar waveguides [20], photonic crystal fibers [24], grating waveguide structures (GWS) [21] [22] and double grating waveguide structures (DGWS) [23]. The DGWS are multilayered structures (two gratings and a thin waveguide layer) that show an abnormal reflection [25] due to the destructive interference between the diffracted and the directly transmitted wave when a guided mode is excited in the waveguide. "
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    ABSTRACT: Two photon fluorescent spectroscopy (TPF) Double grating waveguide structure (DGWS) Alkyl phosphates and phosphonates SAM Tantalum oxide (Ta2O5) a b s t r a c t An immunosensor approach based on non-linear two-photon fluorescence spectroscopy (TPF) coupled to a resonant double grating waveguide structure (DGWS) has been used for the detection of methyl-boldenone (MB), an androgenic anabolic steroid used illegally as growth promoter. This synthetic steroid is detected by the biosensor down to 0.1 g l −1 , two orders of magnitude lower than the minimum required performance limit (MRPL) required by the World Anti-Doping Agency (WADA). Nevertheless, we have focused this work on the synthesis and characterization of small fluorescent-labeled conju-gates, as well as on the modification of the waveguide surfaces. Detection relies on a direct competitive format, using a boldenone–rhodamine conjugate as fluorescent competitor and a specific anti-MB anti-body. The immunoreagents are immobilized onto a resonant Ta 2 O 5 sensing chip after being activated with phosphonohexanoic acid spacers, a novel methodology for covalently surface immobilization of biomolecules, which shows better stability and homogeneity than classical silane chemistries. The devel-oped immunosensor presents great potential as a robust device for its implementation on the detection of small illegal and toxic contaminants.
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