Abstract
We propose in this paper a biosensor scheme based on coupled plasmon-waveguide resonance (CPWR) excited fluorescence spectroscopy. A symmetrical structure that offers higher surface electric field strengths, longer surface propagation lengths and depths is developed to support guided waveguide modes for the efficient excitation of fluorescence. The optimal parameters for the sensor films are theoretically and experimentally investigated, leading to a detection limit of 0.1 nM (for a Cy5 solution). Multiplex analysis possible with the fluorescence detection is further advanced by employing the hyperspectral fluorescence technique to record the full spectra for every pixel on the sample plane. We demonstrate experimentally that highly overlapping fluorescence (Cy5 and Dylight680) can be distinguished and ratios of different emission sources can be determined accurately. This biosensor shows great potential for multiplex detections of fluorescence analytes.
Highlights
IntroductionDue to its high sensitivity and selectivity, fluorescence detection has undergone enormous developments in all the aspects of principles [6], instruments [7] and applications [8,9]
Fluorescence technology, since its introduction to biochemistry in the 1950s, has offered an important analytical tool for both biological research and clinical applications in biological molecules [1], DNA microarray technology [2], cell imaging [3], cancer diagnosis [4] and so on [5].Due to its high sensitivity and selectivity, fluorescence detection has undergone enormous developments in all the aspects of principles [6], instruments [7] and applications [8,9]
In our previous work [23], we proposed surface plasmon resonance (SPR)-supporting sensing structures based on symmetrical coupled plasmon-waveguide resonance (CPWR) and the experimental results showed that the sensing characteristics of this symmetrical CPWR based sensor are greatly improved over conventional SPR sensors
Summary
Due to its high sensitivity and selectivity, fluorescence detection has undergone enormous developments in all the aspects of principles [6], instruments [7] and applications [8,9] Among these achievements, fluorescence-based detection of chemical and biological applications with advanced sensitivity by using surface plasmon-enhanced fluorescence (SPEF) has been a continuous focus of scientific research and led to ever increasing important developments [10,11]. Fluorescence-based detection of chemical and biological applications with advanced sensitivity by using surface plasmon-enhanced fluorescence (SPEF) has been a continuous focus of scientific research and led to ever increasing important developments [10,11] This dark field excitation mode increases the intensity of the fluorescence signal greatly, and avoids the influence of the incident light. Theoretical results indicate that CPWR results in better performance for both detection range and enhanced electromagnetic field which is highly suitable for dark field excitation of fluorescence to maintain an appreciable sensitivity and signal-to-noise ratio [15]
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