Journal
BIOSENSORS & BIOELECTRONICS
Volume 26, Issue 11, Pages 4477-4483Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2011.05.005
Keywords
Microfluidics; Immunoarray; Cancer biomarkers; Off-line protein capture; Gold nanoparticles; Paramagnetic beads
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Funding
- NIEHS/NIH [ES013557]
- Science Foundation Ireland
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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 mu m 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 similar to 90,000 antibodies and similar to 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. (C) 2011 Elsevier B.V. All rights reserved.
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