title: Optical resonance-enhanced absorption-based near-field immunochip biosensor for allergen detection.
abstract: An optical immunochip biosensor has been developed as a rapid method for allergen detection in complex food matrixes, and its application evaluated for the detection of the egg white allergens, ovalbumin and ovomucoid. The optical near-field phenomenon underlying the basic principle of the sensor design is called resonance-enhanced absorption (REA), which utilizes gold nanoparticles (Au NPs) as signal transducers in a highly sensitive interferometric setup. Using this approach, a novel, simple, and rapid colorimetric solid-phase immunoassay on a planar chip substrate was realized in direct and sandwich assay formats, with a detection system that does not require any instrumentation for readout. Semiquantitative immunochemical responses are directly visible to the naked eye of the analyst. The biosensor shows concentration-dependent color development by capturing antibody-functionalized Au NPs on allergen-coated chips and has a detection limit of 1 ng/mL. To establish a rapid method, we took advantage of the physicochemical microenvironment of the Au NP-antibody bioconjugate to be bound directly over an interacting poly(styrene-methyl methacrylate) interlayer by an immobilized antigen. In the direct assay format, a coating time with allergen of only 5 min under "soft" nondenaturing conditions was sufficient for accurate reproducibility and sensitivity. In conclusion, the REA-based immunochip sensor is easy to fabricate, is reproducible and selective in its performance, has minimal technical requirements, and will enable high-throughput screening of affinity binding interactions in technological and medical applications.
authors: Max F. Perutz Laboratories, Department of Biochemistry, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria. irene.maier@univie.ac.at
authors: Irene
authors: I
authors: Maier
authors: Michael R A
authors: MR
authors: Morgan
authors: Wolfgang
authors: W
authors: Lindner
authors: Fritz
authors: F
authors: Pittner
mesh_terms: D000042:Absorption; D000485:Allergens / Q000032:analysis*; D015374:Biosensing Techniques / Q000379:methods*; D005504:Food Analysis / Q000379:methods; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010047:Ovalbumin / Q000032:analysis*; D010059:Ovomucin / Q000032:analysis*; D040081:Protein Array Analysis / Q000379:methods; D020349:Surface Plasmon Resonance / Q000379:methods
chemical_list: D000485:Allergens; D010059:Ovomucin; D006046:Gold; D010047:Ovalbumin