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17 November 2005 Chemical and biological sensing through optical resonances in pendant droplets
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Proceedings Volume 6008, Nanosensing: Materials and Devices II; 60080Q (2005)
Event: Optics East 2005, 2005, Boston, MA, United States
A microdroplet can act as a high quality factor optical cavity that supports Morphology Dependent Resonances(MDRs). Enhanced radiative energy transfer through these optical resonances can also be utilized as a transduction mechanism for chemical and biological sensing. Enhancement in radiative energy transfer is observed when a donor/acceptor pair is present in the resonant medium of a microcavity. Here, we demonstrate avidin-biotin binding and its detection through a FRET pair as a potential application for ultra-sensitive detection for fluoroimmunoassays. The binding interaction between the biotinylated donor molecules and streptavidin-acceptor conjugate was used to observe the energy transfer between the dye pairs. The radial modes of MDRs extend to approximately 0.6 r0 inside the droplet. As a result, the fluorescent emission around the center is not coupled to the optical resonances losing sensitivity. To address this problem, we prepared water-in-oil emulsions of avidin and biotin containing solutions. The water phase contains the streptavidin-Alexa Fluor 610 and the oil phase contains biotinylated fluorescent bead. Streptavidin-biotin binding reaction occurs at the water-oil interface. The water phase accumulates at the droplet air interface due to higher specific density enhancing the resonance coupling. Water and oil phase are index-matched to avoid scattering problems. As a result, a large portion of the avidin-biotin complex was localized at the pendant droplet and air interface. Strong coupling of acceptor emission into optical resonances shows that the energy transfer is efficiently mediated through these resonances.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Melikhan Tanyeri, Dosi Dosev, and Ian M. Kennedy "Chemical and biological sensing through optical resonances in pendant droplets", Proc. SPIE 6008, Nanosensing: Materials and Devices II, 60080Q (17 November 2005);

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