Chemical and biological sensing through optical resonances in pendant droplets

Melikhan Tanyeri, Dosi Dosev, Ian M. Kennedy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


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 r 0 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.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsM.S. Islam, A.K. Dutta
StatePublished - 2005
EventNanosensing: Materials and Devices II - Boston, MA, United States
Duration: Oct 23 2005Oct 26 2005


OtherNanosensing: Materials and Devices II
Country/TerritoryUnited States
CityBoston, MA


  • Fluorescence
  • FRET
  • MDRs
  • Microcavity

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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