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Novel readout method for molecular diagnostic assays based on optical measurements of magnetic nanobead dynamics
Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech.
Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
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2015 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 87, no 3, 1622-1629 p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate detection of DNA coils formed from a Vibrio cholerae DNA target at picomolar concentrations using a novel optomagnetic approach exploiting the dynamic behavior and optical anisotropy of magnetic nanobead (MNB) assemblies. We establish that the complex second harmonic optical transmission spectra of MNB suspensions measured upon application of a weak uniaxial AC magnetic field correlate well with the rotation dynamics of the individual MNBs. Adding a target analyte to the solution leads to the formation of permanent MNB clusters, namely, to the suppression of the dynamic MNB behavior. We prove that the optical transmission spectra are highly sensitive to the formation of permanent MNB clusters and, thereby to the target analyte concentration. As a specific clinically relevant diagnostic case, we detect DNA coils formed via padlock probe recognition and isothermal rolling circle amplification and benchmark against a commercial equipment. The results demonstrate the fast optomagnetic readout of rolling circle products from bacterial DNA utilizing the dynamic properties of MNBs in a miniaturized and low-cost platform requiring only a transparent window in the chip.

Place, publisher, year, edition, pages
2015. Vol. 87, no 3, 1622-1629 p.
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-210686DOI: 10.1021/ac503191vISI: 000349059000031PubMedID: 25539065OAI: oai:DiVA.org:uu-210686DiVA: diva2:664027
Funder
Swedish Research Council Formas, 221-2012-444Swedish Research Council Formas, BioBridgesSwedish Research CouncilSwedish Foundation for Strategic Research Knut and Alice Wallenberg Foundation
Available from: 2013-11-13 Created: 2013-11-13 Last updated: 2017-12-06
In thesis
1. Biomolecular Recognition Based on Field Induced Magnetic Bead Dynamics
Open this publication in new window or tab >>Biomolecular Recognition Based on Field Induced Magnetic Bead Dynamics
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, three different read-out techniques for biomolecular recognition have been studied. All three techniques rely on the change in dynamic behaviour of probe functionalised magnetic beads after binding to a biomolecular target complementary to the probe.

In the first technique presented, the sample is exposed to an AC magnetic field while the response to this field is probed using a laser source and a photodetector positioned at opposite sides of the sample. Beads bound to the target entity will experience an increase in their hydrodynamic volume, and will not be able to respond as rapidly to an alternating field as free beads. Here, the target entity is either DNA coils formed by rolling circle amplification or biotinylated bovine serum albumin (bBSA). The change in dynamic behaviour is measured as a frequency dependent modulation of transmitted light. Limit of detections (LODs) of 5 pM DNA coils originating from a V. cholerae target and 100 pM of bBSA have been achieved.

In the second technique presented, the beads are magnetically transported across a probe functionalised detection area on a microchip. Beads bound to a target will be blocked from interaction with the detection area probes, whereas in the absence of a target, beads will be immobilised on the detection area. The LOD of biotin for this system proved to be in the range of 20 to 50 ng/ml.

In the third technique presented, the sample is microfluidically transported to a detection area on a microchip. The read-out is performed using a planar Hall effect bridge sensor. A sinusoidal current is applied to the bridge in one direction and the sensor output voltage is measured across the sensor in the perpendicular direction. The AC current induced bead magnetisation contributing to the sensor output will appear different for free beads compared to beads bound to a target. LODs of 500 B. globigii spores and 2 pM of V. cholerae DNA coils were achieved.

From a lab-on-a-chip point of view, all three techniques considered in this thesis show promising results with regards to sensitivity and integrability.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 94 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1193
Keyword
Magnetic biosensor, magnetic nanoparticle, DNA detection
National Category
Nano Technology Biochemistry and Molecular Biology Condensed Matter Physics
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-234302 (URN)978-91-554-9077-5 (ISBN)
Public defence
2014-12-12, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Available from: 2014-11-21 Created: 2014-10-15 Last updated: 2015-02-03

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Stjernberg Bejhed, RebeccaZardán Gómez de la Torre, TeresaStrömberg, MattiasStrömme, MariaSvedlindh, Peter

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