title: Detection of ochratoxin A in beer samples with a label-free monolithically integrated optoelectronic biosensor.
abstract: An optical biosensor for label-free detection of ochratoxin A (OTA) in beer samples is presented. The biosensor consists of an array of ten Mach-Zehnder interferometers (MZIs) monolithically integrated along with their respective broad-band silicon light sources on the same Si chip (37mm2). The chip was transformed to biosensor by functionalizing the MZIs sensing arms with an OTA-ovalbumin conjugate. OTA determination was performed by pumping over the chip mixtures of calibrators or samples with anti-OTA antibody following a competitive immunoassay format. An external miniaturized spectrometer was employed to continuously record the transmission spectra of each interferometer. Spectral shifts obtained due to immunoreaction were transformed to phase shifts through Discrete Fourier Transform. The assay had a detection limit of 2.0ng/ml and a dynamic range 4.0-100ng/ml in beer samples, recoveries ranging from 90.6 to 116%, and intra- and inter-assay coefficients of variation of 9% and 14%, respectively. The results obtained with the sensor using OTA-spiked beer samples spiked were in good agreement with those obtained by an ELISA developed using the same antibody. The good analytical performance of the biosensor and the small size of the proposed chip provide for the development of a portable instrument for point-of-need determinations.
authors.affiliation: Immunoassays-Immunosensors Lab, INRaSTES, NCSR "Demokritos", Aghia Paraskevi 15310, Greece; Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Varvara
authors.initials: V
authors.lastname: Pagkali
authors.affiliation: Immunoassays-Immunosensors Lab, INRaSTES, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Panagiota S
authors.initials: PS
authors.lastname: Petrou
authors.affiliation: Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Salapatas
authors.affiliation: Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Makarona
authors.affiliation: RIKILT Wageningen UR, Akkermaalsbos 2, 6708 WB, Wageningen, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Peters
authors.affiliation: RIKILT Wageningen UR, Akkermaalsbos 2, 6708 WB, Wageningen, The Netherlands.
authors.forename: Willem
authors.initials: W
authors.lastname: Haasnoot
authors.affiliation: Jobst Technologies GmbH, Freiburg, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Jobst
authors.affiliation: Analytical Chemistry Lab, Department of Chemistry, University of Athens, Panepistimiopolis Zografou, 15771, Greece.
authors.forename: Anastasios
authors.initials: A
authors.lastname: Economou
authors.affiliation: Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Misiakos
authors.affiliation: Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Aghia Paraskevi 15310, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Raptis
authors.affiliation: Immunoassays-Immunosensors Lab, INRaSTES, NCSR "Demokritos", Aghia Paraskevi 15310, Greece. Electronic address: skakab@rrp.demokritos.gr.
authors.forename: Sotirios E
authors.initials: SE
authors.lastname: Kakabakos
mesh_terms: D001515:Beer / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D007118:Immunoassay; D007368:Interferometry / Q000295:instrumentation / Q000379:methods; D057230:Limit of Detection; D009793:Ochratoxins / Q000032:analysis*; D055620:Optical Phenomena; D012825:Silicon / Q000737:chemistry*
chemical_list: D009793:Ochratoxins; C025589:ochratoxin A; D012825:Silicon
keywords: Beer; Label-free detection; Monolithically integrated Mach-Zehnder interferometers; Ochratoxin A