title: Electrochemical detection of the toxic dinoflagellate Alexandrium ostenfeldii with a DNA-biosensor.
abstract: The steady rise of observations of harmful or toxic algal blooms throughout the world in the past decades constitute a menace for coastal ecosystems and human interests. As a consequence, a number of programs have been launched to monitor the occurrence of harmful and toxic algae. However, the identification is currently done by microscopic examination, which requires a broad taxonomic knowledge, expensive equipment and is very time consuming. In order to facilitate the identification of toxic algae, an inexpensive and easy-to-handle DNA-biosensor has been adapted for the electrochemical detection of the toxic dinoflagellate Alexandrium ostenfeldii. The detection of the toxic algae is based on a sandwich hybridisation, which is carried out on a disposable sensor chip. A set of two probes for the species-specific identification of A. ostenfeldii was developed. The specificity of the probes could be shown in dot-blot hybridisations and with the DNA-biosensor. The sensitivity of the DNA-biosensor was optimised with respect to hybridisation temperature and NaCl-concentration and a significant increase of the sensitivity of the DNA-biosensor could be obtained by a fragmentation of the rRNA prior to the hybridisation and by adding a helper oligonucleotide, which binds in close proximity to the probes to the hybridisation.
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany. kmetfies@awi-bremerhaven.de
authors.forename: Katja
authors.initials: K
authors.lastname: Metfies
authors.forename: Susanne
authors.initials: S
authors.lastname: Huljic
authors.forename: Martin
authors.initials: M
authors.lastname: Lange
authors.forename: Linda K
authors.initials: LK
authors.lastname: Medlin
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D004247:DNA; D004141:Dinoflagellida / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D015335:Molecular Probes; D012335:RNA, Ribosomal
chemical_list: D015335:Molecular Probes; D012335:RNA, Ribosomal; D004247:DNA