title: Allergen immobilisation and signal amplification by quantum dots for use in a biosensor assay of IgE in serum.
abstract: The production of biosensors for point of care diagnostics usually requires the immobilisation and storage of protein (for example, antigen or antibody) on a sensor surface, in a manner that retains a high degree of activity and low levels of non-specific binding. These characteristics have been assessed for polymer immobilised antigens (allergens) using an IgG binding assay and demonstrated further by assay with serum containing reactive IgEs. The activity of allergens immobilised on sensor chips using copoly(DMA-NAS-MAPS) and a spotting technique, as well as the specificity of their binding interactions with cognate immunoglobulins was assessed using Dual Polarisation Interferometry (DPI). The data obtained indicate that the allergens studied remain stable over long periods of time (at least 114 days). This performance compared favourably with other immobilisation methods. Allergen coated chips were tested in an anti-casein IgE assay using human serum from allergic and non-allergic donors. Detection of both total Ig and specific IgE was demonstrated using a secondary anti-IgE antibody. Furthermore, optical signal enhancement with streptavidin conjugated quantum dots was shown to yield responses for samples below 0.84 ng/mL (0.35 KU/L) of IgE, which overlap with the industrial quasi-standard ImmunoCAP(®) and is the clinically relevant threshold used to classify serum samples from allergic individuals.
authors.affiliation: Farfield Group Ltd., 3000 Manchester Business Park, Aviator Way, Manchester M22 5GT, UK.
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Platt
authors.forename: Francesco
authors.initials: F
authors.lastname: Damin
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Swann
authors.forename: Isabelle
authors.initials: I
authors.lastname: Metton
authors.forename: Gilbert
authors.initials: G
authors.lastname: Skorski
authors.forename: Marina
authors.initials: M
authors.lastname: Cretich
authors.forename: Marcella
authors.initials: M
authors.lastname: Chiari
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000888:Antibodies, Anti-Idiotypic / Q000737:chemistry / Q000276:immunology; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D015374:Biosensing Techniques; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood / Q000302:isolation & purification; D011108:Polymers / Q000737:chemistry; D015800:Protozoan Proteins / Q000737:chemistry / Q000276:immunology*; D045663:Quantum Dots
chemical_list: D000485:Allergens; D000888:Antibodies, Anti-Idiotypic; D000953:Antigens, Protozoan; D011108:Polymers; D015800:Protozoan Proteins; C026408:anti-IgE antibodies; C043323:immobilization antigens; D007073:Immunoglobulin E
keywords: Allergen; Biosensor; Interferometry; Polymer coating; Quantum dots