title: Microfluidic electrochemical immunoarray for ultrasensitive detection of two cancer biomarker proteins in serum.
abstract: A microfluidic electrochemical immunoassay system for multiplexed detection of protein cancer biomarkers was fabricated using a molded polydimethylsiloxane channel and routine machined parts interfaced with a pump and sample injector. Using off-line capture of analytes by heavily-enzyme-labeled 1 μm superparamagnetic particle (MP)-antibody bioconjugates and capture antibodies attached to an 8-electrode measuring chip, simultaneous detection of cancer biomarker proteins prostate specific antigen (PSA) and interleukin-6 (IL-6) in serum was achieved at sub-pg mL⁻¹ levels. MPs were conjugated with ∼90,000 antibodies and ∼200,000 horseradish peroxidase (HRP) labels to provide efficient off-line capture and high sensitivity. Measuring electrodes feature a layer of 5 nm glutathione-decorated gold nanoparticles to attach antibodies that capture MP-analyte bioconjugates. Detection limits of 0.23 pg mL⁻¹ for PSA and 0.30 pg mL⁻¹ for IL-6 were obtained in diluted serum mixtures. PSA and IL-6 biomarkers were measured in serum of prostate cancer patients in total assay time 1.15 h and sensor array results gave excellent correlation with standard enzyme-linked immunosorbent assays (ELISA). These microfluidic immunosensors employing nanostructured surfaces and off-line analyte capture with heavily labeled paramagnetic particles hold great promise for accurate, sensitive multiplexed detection of diagnostic cancer biomarkers.
authors.affiliation: Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA.
authors.forename: Bhaskara V
authors.initials: BV
authors.lastname: Chikkaveeraiah
authors.forename: Vigneshwaran
authors.initials: V
authors.lastname: Mani
authors.forename: Vyomesh
authors.initials: V
authors.lastname: Patel
authors.forename: J Silvio
authors.initials: JS
authors.lastname: Gutkind
authors.forename: James F
authors.initials: JF
authors.lastname: Rusling
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D055664:Electrochemical Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D004867:Equipment Design; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D015850:Interleukin-6 / Q000097:blood; D058185:Magnetite Nanoparticles; D008297:Male; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood
chemical_list: D014408:Biomarkers, Tumor; C508600:IL6 protein, human; D015850:Interleukin-6; D058185:Magnetite Nanoparticles; D017430:Prostate-Specific Antigen