Ulrich Y Schaff1, Greg J Sommer. 1. Biotechnology and Bioengineering Department, Sandia National Laboratories, Livermore, CA 94550, USA.
Abstract
BACKGROUND: Centrifugal "lab on a disk" microfluidics is a promising avenue for developing portable, low-cost, automated immunoassays. However, the necessity of incorporating multiple wash steps results in complicated designs that increase the time and sample/reagent volumes needed to run assays and raises the probability of errors. We present proof of principle for a disk-based microfluidic immunoassay technique that processes blood samples without conventional wash steps. METHODS: Microfluidic disks were fabricated from layers of patterned, double-sided tape and polymer sheets. Sample was mixed on-disk with assay capture beads and labeling antibodies. Following incubation, the assay beads were physically separated from the blood cells, plasma, and unbound label by centrifugation through a density medium. A signal-laden pellet formed at the periphery of the disk was analyzed to quantify concentration of the target analyte. RESULTS: To demonstrate this technique, the inflammation biomarkers C-reactive protein and interleukin-6 were measured from spiked mouse plasma and human whole blood samples. On-disk processing (mixing, labeling, and separation) facilitated direct assays on 1-μL samples with a 15-min sample-to-answer time, <100 pmol/L limit of detection, and 10% CV. We also used a unique single-channel multiplexing technique based on the sedimentation rate of different size or density bead populations. CONCLUSIONS: This portable microfluidic system is a promising method for rapid, inexpensive, and automated detection of multiple analytes directly from a drop of blood in a point-of-care setting.
BACKGROUND: Centrifugal "lab on a disk" microfluidics is a promising avenue for developing portable, low-cost, automated immunoassays. However, the necessity of incorporating multiple wash steps results in complicated designs that increase the time and sample/reagent volumes needed to run assays and raises the probability of errors. We present proof of principle for a disk-based microfluidic immunoassay technique that processes blood samples without conventional wash steps. METHODS: Microfluidic disks were fabricated from layers of patterned, double-sided tape and polymer sheets. Sample was mixed on-disk with assay capture beads and labeling antibodies. Following incubation, the assay beads were physically separated from the blood cells, plasma, and unbound label by centrifugation through a density medium. A signal-laden pellet formed at the periphery of the disk was analyzed to quantify concentration of the target analyte. RESULTS: To demonstrate this technique, the inflammation biomarkers C-reactive protein and interleukin-6 were measured from spiked mouse plasma and human whole blood samples. On-disk processing (mixing, labeling, and separation) facilitated direct assays on 1-μL samples with a 15-min sample-to-answer time, <100 pmol/L limit of detection, and 10% CV. We also used a unique single-channel multiplexing technique based on the sedimentation rate of different size or density bead populations. CONCLUSIONS: This portable microfluidic system is a promising method for rapid, inexpensive, and automated detection of multiple analytes directly from a drop of blood in a point-of-care setting.
Authors: Christopher R Phaneuf; Betty Mangadu; Huu M Tran; Yooli K Light; Anchal Sinha; Frank W Charbonier; Tyler P Eckles; Anup K Singh; Chung-Yan Koh Journal: Biosens Bioelectron Date: 2018-08-10 Impact factor: 10.618
Authors: A Ahmad Tajudin; K Petersson; A Lenshof; A-M Swärd-Nilsson; L Aberg; G Marko-Varga; J Malm; H Lilja; T Laurell Journal: Lab Chip Date: 2013-05-07 Impact factor: 6.799
Authors: Chung-Yan Koh; Ulrich Y Schaff; Matthew E Piccini; Larry H Stanker; Luisa W Cheng; Easwaran Ravichandran; Bal-Ram Singh; Greg J Sommer; Anup K Singh Journal: Anal Chem Date: 2015-01-05 Impact factor: 6.986