@article{MuribYeapMartensetal.2014,
  author    = {Murib, Mohammed Sharif and Yeap, Weng-Siang and Martens, Daan and Bienstman, Peter and Ceuninck, Ward de and Grinsven, Bart van and Sch{\"o}ning, Michael Josef and Michiels, Luc and Haenen, Ken and Ameloot, Marcel and Serpeng{\"u}zel, Ali and Wagner, Patrick},
  title     = {Photonic detection and characterization of DNA using sapphire microspheres},
  series = {Journal of biomedical optics},
  volume    = {19},
  journal   = {Journal of biomedical optics},
  number    = {9},
  publisher = {SPIE},
  address   = {Bellingham},
  issn      = {1560-2281 (E-Journal); 1083-3668 (Print)},
  doi       = {10.1117/1.JBO.19.9.097006},
  pages     = {097006},
  year      = {2014},
  abstract  = {A microcavity-based deoxyribonucleic acid (DNA) optical biosensor is demonstrated for the first time using synthetic sapphire for the optical cavity. Transmitted and elastic scattering intensity at 1510 nm are analyzed from a sapphire microsphere (radius 500  μm, refractive index 1.77) on an optical fiber half coupler. The 0.43 nm angular mode spacing of the resonances correlates well with the optical size of the sapphire sphere. Probe DNA consisting of a 36-mer fragment was covalently immobilized on a sapphire microsphere and hybridized with a 29-mer target DNA. Whispering gallery modes (WGMs) were monitored before the sapphire was functionalized with DNA and after it was functionalized with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The shift in WGMs from the surface modification with DNA was measured and correlated well with the estimated thickness of the add-on DNA layer. It is shown that ssDNA is more uniformly oriented on the sapphire surface than dsDNA. In addition, it is shown that functionalization of the sapphire spherical surface with DNA does not affect the quality factor (Q≈104) of the sapphire microspheres. The use of sapphire is especially interesting because this material is chemically resilient, biocompatible, and widely used for medical implants.},
  language  = {en}
}