Label-free detection of ovarian cancer biomarkers using whispering gallery mode imaging

Heath A. Huckabay, Sarah M. Wildgen, Robert C. Dunn

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Small optical microresonators that support whispering gallery mode (WGM) resonances are emerging as powerful new platforms for biosensing. These resonators respond to changes in refractive index and potentially offer many advantages for label-free sensing. Recently we reported an approach for detecting WGM resonances based on fluorescence imaging and demonstrated its utility by quantifying the ovarian cancer marker CA-125 in buffer. Here we extend those measurements by reporting a simplified approach for launching WGM resonances using excitation light coupled into a Dove prism. The enhanced phase matching enables significant improvements in signal-to-noise, revealing the mode structure present in each resonator. As with all label-free biosensing techniques, non-specific interactions can be limiting. Here we show that standard blocking protocols reduce non-specific interactions sufficiently to enable CA-125 quantification in serum samples. Finally, fluorescence imaging of WGM resonances offers the potential for large scale multiplexed detection which is demonstrated here by simultaneously exciting and imaging over 120 microsphere resonators. For multiplexed applications, analyte identity can be encoded in the resonator size and/or location. By encoding analyte identity into microresonator size, we simultaneously quantify the putative ovarian cancer markers osteopontin (38. μm diameter sphere), CA-125 (53. μm diameter sphere), and prolactin (63. μm diameter sphere) in a single PBS assay. Together, these results show that fluorescence imaging of WGM resonances offers a promising new approach for the highly multiplexed detection of biomarkers in complex biological fluids.

Original languageEnglish
Pages (from-to)223-229
Number of pages7
JournalBiosensors and Bioelectronics
Volume45
Issue number1
DOIs
StatePublished - Jul 5 2013

Funding

S.M.W. gratefully acknowledges support from the Madison and Lila Self Graduate Fellowship. This work is generously supported by NSF ( CBET 1133814 ).

Keywords

  • Fluorescence imaging
  • Label-free
  • Multiplexed
  • Optical resonators
  • Ovarian cancer
  • Whispering gallery mode

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