title: Optimal design of microarray immunoassays to compensate for kinetic limitations: theory and experiment.
abstract: In this report we examine the limitations of existing microarray immunoassays and investigate how best to optimize them using theoretical and experimental approaches. Derived from DNA technology, microarray immunoassays present a major technological challenge with much greater physicochemical complexity. A key physicochemical limitation of the current generation of microarray immunoassays is a strong dependence of antibody microspot kinetics on the mass flux to the spot as was reported by us previously. In this report we analyze, theoretically and experimentally, the effects of microarray design parameters (incubation vessel geometry, incubation time, stirring, spot size, antibody-binding site density, etc.) on microspot reaction kinetics and sensitivity. Using a two-compartment model, the quantitative descriptors of the microspot reaction were determined for different incubation and microarray design conditions. This analysis revealed profound mass transport limitations in the observed kinetics, which may be slowed down as much as hundreds of times compared with the solution kinetics. The data obtained were considered with relevance to microspot assay diffusional and adsorptive processes, enabling us to validate some of the underlying principles of the antibody microspot reaction mechanism and provide guidelines for optimal microspot immunoassay design. For an assay optimized to maximize the reaction velocity on a spot, we demonstrate sensitivities in the am and low fm ranges for a system containing a representative sample of antigen-antibody pairs. In addition, a separate panel of low abundance cytokines in blood plasma was detected with remarkably high signal-to-noise ratios.
authors.affiliation: Division of Functional Genome Analysis, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany. w.kusnezow@dkfz.de
authors.forename: Wlad
authors.initials: W
authors.lastname: Kusnezow
authors.forename: Yana V
authors.initials: YV
authors.lastname: Syagailo
authors.forename: Sven
authors.initials: S
authors.lastname: Rüffer
authors.forename: Nina
authors.initials: N
authors.lastname: Baudenstiel
authors.forename: Christoph
authors.initials: C
authors.lastname: Gauer
authors.forename: Jörg D
authors.initials: JD
authors.lastname: Hoheisel
authors.forename: David
authors.initials: D
authors.lastname: Wild
authors.forename: Igor
authors.initials: I
authors.lastname: Goychuk
mesh_terms: D000936:Antigen-Antibody Complex; D000937:Antigen-Antibody Reactions; D000941:Antigens / Q000378:metabolism*; D001665:Binding Sites; D001666:Binding Sites, Antibody; D006433:Hemocyanins / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007118:Immunoassay; D007700:Kinetics; D008954:Models, Biological; D008962:Models, Theoretical; D040081:Protein Array Analysis / Q000379:methods*; D011485:Protein Binding; D013954:Thyroglobulin / Q000276:immunology / Q000378:metabolism
chemical_list: D000936:Antigen-Antibody Complex; D000941:Antigens; D013954:Thyroglobulin; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin