Mw. S. (Sabina) Rebe Raz: “On-Chip Food Safety Monitoring: Multi-analyte Screening with Imaging Surface Plasmon Resonance-based Biosensor”

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13 sep 2010 13:30
Onderdeel: Wageningen University
Locatie: Aula, gebouw 362, Gen. Foulkesweg 1, Wageningen
Organisatie: Wageningen University
Promotor: prof.dr.ir. W. Norde (Bionanotechnologie)
Co-Promotor: Dr.ir. M.G.E.G. Bremer

 This thesis describes on-chip detection of health-threatening compounds in food, using imaging Surface Plasmon Resonance (iSPR) biosensor. iSPR biosensor combines spatial modification of the sensor chip surface with SPR-based detection, enabling label free and multiplexed analysis in a single measurement. Within the scope of this thesis the iSPR biosensor was evaluated for sensitivity, robustness and potential applicability to measurements in food samples. Simultaneous detection of seven antibiotic residues was achieved by combining an antibiotics-microarrayed chip with seven immunoassays in a competitive format. The developed on-chip antibiotic residues detection method showed ppb sensitivities for the multiplexed measurements in milk. Further on, an allergen chip was developed for food allergen detection in cookies and dark chocolates. Here, the chip was microarrayed with specific anti-allergen antibodies and the allergen proteins were detected in the food sample directly. With this chip, 12 major allergens were simultaneously detected with ppm sensitivity in several cookies and dark chocolate samples from different manufacturers. Both methods developed here displayed sufficient sensitivity for food monitoring and short measurements times (below 10 minutes per sample). This thesis also describes a novel approach to tackle the most common drawback of using SPR biosensors for measurements in complex biological matrices - the nonspecific binding to the sensor chip surface. By using a perforated membrane supported by a polymeric gel structure that exceeds the evanescent wave penetration depth, a nano-filter was created. This nano-filter prevented the diffusion of large particles and/or aggregates that bound non-specifically and interfered with the specific analyte detection. On the whole, it was demonstrated that by using iSPR-based biosensors, one can obtain robust and quantitative information on multiple analytes concentration, benefiting from high multiplexing capabilities and short measurement times together with no need for complex and time consuming sample preparation steps.
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