title: Electrochemical biosensor for quantitation of anti-DNA autoantibodies in human serum.
abstract: Measurement of serum autoantibody is a critical tool in the diagnosis and management of autoimmune diseases. However, rapid and convenient methods at the point-of care have not been achieved in large part because any one antibody species is a heterogeneous and miniscule fraction of the total serum immunoglobulin displaying identical properties other than its antigen-binding specificity. The present system addresses these challenges by vacuum-mediated transport of diluted serum through an antigen-coated porous membrane. To measure anti-DNA autoantibodies, native DNA was immobilized into a poly(vinylidene fluoride) membrane pre-coated with a synthetic phenylalanine/lysine co-polymer. Flow-through of primary and peroxidase-conjugated secondary antibodies over the course of 3 min enhanced productive antibody-antigen interactions by bringing the reactants into close mutual proximity. Signal was quantified electrochemically during the enzymatic conversion of the tetramethylbenzidine substrate to a charge-transfer complex. The electrochemical signals generated by sera from patients with systemic lupus erythematosus using this device showed good quantitative correlation with a standard enzyme-linked immunosorbent assay and displayed similar detection limits. Inter- and intra-assay variability and electrode uniformity were favorable as was a two-month test of the stability of the DNA-coated membrane. While refining the fluidics requirements of this biosensor will be needed, its capacity to quantify over the course of 30 min anti-DNA antibodies in fresh human serum without background reactivity of normal serum makes this a promising technology as a point-of care device of clinical utility.
authors: Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA. Electronic address: rlrubin@salud.unm.edu.
authors: Robert L
authors: RL
authors: Rubin
authors: David
authors: D
authors: Wall
authors: Konstantin N
authors: KN
authors: Konstantinov
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation; D055664:Electrochemical Techniques / Q000191:economics / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000191:economics / Q000295:instrumentation; D057230:Limit of Detection; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000175:diagnosis; D013997:Time Factors
chemical_list: D000974:Antibodies, Antinuclear
keywords: Anti-DNA autoantibody; Electrochemical flow-through biosensor; Human serum