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.

Advanced DNA- and Protein-based Methods for the Detection and Investigation of Food Allergens

“…Likewise, a similar approach was used for the detection of the egg white allergens ovalbumin and ovomucoid with a detection limit of 1 ng/mL (Maier et al, 2008).…”

Sensitive biosensing strategy based on functional nanomaterials

“…Metal nanoparticles, such as gold and silver nanoparticles, exhibit plasmon absorbance bands in the visible spectral region that are controlled by the size of the respective particles. The unique plasmon absorbance features of Au NPs and specifically the interparticle-coupled plasmon absorbance of conjugated particles have been widely used for DNA [17] and antibody-antigen [18] analyses. By using a carboxylated dextran film to eliminate nonspecific adsorption of ODNcapped Au NPs, a signal amplification method has been designed to show a remarkable detection limit of DNA as low as 2.1×10 −20 mol, corresponding to 1.38 fM [19].…”

Detection of Food Allergens

“…The detection of allergenic material in foods by using biosensor technology has been limited to a few antibody-based applications (Mohammed et al, 2001;Lu et al, 2004;Yman et al, 2006;Hohensinner et al, 2007;Maier et al, 2008). However, it has the potential to be developed for DNA or PCR product detection.…”