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) https://doi.org/10.1117/12.631080
Event: Optics East 2005, 2005, Boston, MA, United States
Abstract
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.
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Melikhan Tanyeri, Melikhan Tanyeri, Dosi Dosev, Dosi Dosev, Ian M. Kennedy, 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); doi: 10.1117/12.631080; https://doi.org/10.1117/12.631080
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