title: Lab-on-a-disc agglutination assay for protein detection by optomagnetic readout and optical imaging using nano- and micro-sized magnetic beads.
abstract: We present a biosensing platform for the detection of proteins based on agglutination of aptamer coated magnetic nano- or microbeads. The assay, from sample to answer, is integrated on an automated, low-cost microfluidic disc platform. This ensures fast and reliable results due to a minimum of manual steps involved. The detection of the target protein was achieved in two ways: (1) optomagnetic readout using magnetic nanobeads (MNBs); (2) optical imaging using magnetic microbeads (MMBs). The optomagnetic readout of agglutination is based on optical measurement of the dynamics of MNB aggregates whereas the imaging method is based on direct visualization and quantification of the average size of MMB aggregates. By enhancing magnetic particle agglutination via application of strong magnetic field pulses, we obtained identical limits of detection of 25pM with the same sample-to-answer time (15min 30s) using the two differently sized beads for the two detection methods. In both cases a sample volume of only 10µl is required. The demonstrated automation, low sample-to-answer time and portability of both detection instruments as well as integration of the assay on a low-cost disc are important steps for the implementation of these as portable tools in an out-of-lab setting.
authors.affiliation: Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby, Denmark. Electronic address: rokud@nanotech.dtu.dk.
authors.forename: Rokon
authors.initials: R
authors.lastname: Uddin
authors.affiliation: BluSense Diagnostics, Fruebjergvej 3, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Robert
authors.initials: R
authors.lastname: Burger
authors.affiliation: BluSense Diagnostics, Fruebjergvej 3, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Marco
authors.initials: M
authors.lastname: Donolato
authors.affiliation: Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Jeppe
authors.initials: J
authors.lastname: Fock
authors.affiliation: BluSense Diagnostics, Fruebjergvej 3, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Creagh
authors.affiliation: Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Mikkel Fougt
authors.initials: MF
authors.lastname: Hansen
authors.affiliation: Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Anja
authors.initials: A
authors.lastname: Boisen
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D056656:Lab-On-A-Chip Devices / Q000191:economics; D060526:Magnetic Fields; D008280:Magnetics; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D061848:Optical Imaging / Q000191:economics / Q000295:instrumentation*; D013917:Thrombin / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D058185:Magnetite Nanoparticles; C081676:thrombin aptamer; D013917:Thrombin
keywords: Agglutination assay; Magnetic bead; Microfluidic disc; Optical imaging method; Optomagnetic readout method; Thrombin