title: Photonic detection and characterization of DNA using sapphire microspheres.
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 . ≈ 04) of the sapphire microspheres. The use of sapphire is especially interesting because this material is chemically resilient, biocompatible, and widely used for medical implants.
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, Belgium.
authors.forename: Mohammed Sharif
authors.initials: MS
authors.lastname: Murib
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, Belgium.
authors.forename: Weng-Siang
authors.initials: WS
authors.lastname: Yeap
authors.affiliation: Ghent University-Information Technology, Department of Information Technology, Photonics Research Group, Sint-Pietersnieuwstraat 41, B-9000 Gent, Belgium.
authors.forename: Daan
authors.initials: D
authors.lastname: Martens
authors.affiliation: Ghent University-Information Technology, Department of Information Technology, Photonics Research Group, Sint-Pietersnieuwstraat 41, B-9000 Gent, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Bienstman
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, BelgiumcInteruniversitair Microelectronica Centrum vereniging zonder winstoogmerk, Division Instituut voor Materiaalonderzoek in de Micro-Elektronica, Wetenschaps.
authors.forename: Ward
authors.initials: W
authors.lastname: De Ceuninck
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, BelgiumcInteruniversitair Microelectronica Centrum vereniging zonder winstoogmerk, Division Instituut voor Materiaalonderzoek in de Micro-Elektronica, Wetenschaps.
authors.forename: Bart
authors.initials: B
authors.lastname: van Grinsven
authors.affiliation: Aachen University of Applied Sciences, Institute of Nano- and Biotechnologies, Heinrich-Mußmann-Straße 1, D-52428 Jülich, Germany.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schöning
authors.affiliation: Hasselt University, BIOMED, Agoralaan Building C, B-3590 Diepenbeek, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Michiels
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, BelgiumcInteruniversitair Microelectronica Centrum vereniging zonder winstoogmerk, Division Instituut voor Materiaalonderzoek in de Micro-Elektronica, Wetenschaps.
authors.forename: Ken
authors.initials: K
authors.lastname: Haenen
authors.affiliation: Hasselt University, BIOMED, Agoralaan Building C, B-3590 Diepenbeek, Belgium.
authors.forename: Marcel
authors.initials: M
authors.lastname: Ameloot
authors.affiliation: Koç University, Department of Physics, Microphotonics Research Laboratory, Rumelifeneri Yolu, Sariyer, Istanbul 34450, Turkey.
authors.forename: Ali
authors.initials: A
authors.lastname: Serpengüzel
authors.affiliation: Hasselt University, Instituut voor Materiaalonderzoek, Wetenschapspark 1, B-3590 Diepenbeek, BelgiumcInteruniversitair Microelectronica Centrum vereniging zonder winstoogmerk, Division Instituut voor Materiaalonderzoek in de Micro-Elektronica, Wetenschaps.
authors.forename: Patrick
authors.initials: P
authors.lastname: Wagner
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D004247:DNA / Q000032:analysis / Q000737:chemistry*; D008027:Light; D018613:Microscopy, Confocal; D008863:Microspheres; D055095:Optics and Photonics / Q000379:methods*; D012542:Scattering, Radiation
chemical_list: D004247:DNA; D000537:Aluminum Oxide