title: Detection of unlabeled oligonucleotide targets using whispering gallery modes in single, fluorescent microspheres.
abstract: The development of an inexpensive, highly sensitive, whispering gallery mode (WGM) based biosensing system is demonstrated. The system comprises a silica microsphere functionalized with a fluorophore and a dense monolayer of single-strand oligonucleotides. The adsorption of the complementary strand causes spectral shifts in the emission spectrum of the microsphere that can be registered using a conventional optical microscope and CCD detector. The system is capable of detecting low-abundance, unlabeled-oligonucleotide targets. The spectral shifts can be used to monitor both the hybridization kinetics and the denaturation of the double-strand DNA at elevated temperatures. The hybridization appears to be completely reversible. Complementary oligonucleotide probes more than 30 bases in length are most readily detected while a complete assay takes only a few minutes.
authors.affiliation: School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Edin
authors.initials: E
authors.lastname: Nuhiji
authors.forename: Paul
authors.initials: P
authors.lastname: Mulvaney
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry* / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008863:Microspheres; D036103:Nanotechnology / Q000379:methods*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013194:Staining and Labeling
chemical_list: D004247:DNA