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On-Chip Detection of Rolling Circle Amplified DNA Molecules from Bacillus Globigii Spores and Vibrio Cholerae
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
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2014 (English)In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 10, no 14, 2877-2882 p.Article in journal (Refereed) Published
Abstract [en]

For the first time DNA coils formed by rolling circle amplification are quantified on-chip by Brownian relaxation measurements on magnetic nanobeads using a magnetoresistive sensor. No external magnetic fields are required besides the magnetic field arising from the current through the sensor, which makes the setup very compact. Limits of detection down to 500 Bacillus globigii spores and 2 pM of Vibrio cholerae are demonstrated, which are on the same order of magnitude or lower than those achieved previously using a commercial macro-scale AC susceptometer. The chip-based readout is an important step towards the realization of field tests based on rolling circle amplification molecular analyses.

Place, publisher, year, edition, pages
2014. Vol. 10, no 14, 2877-2882 p.
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Solid State Physics
URN: urn:nbn:se:uu:diva-223848DOI: 10.1002/smll.201303325ISI: 000340660900019PubMedID: 24616417OAI: oai:DiVA.org:uu-223848DiVA: diva2:714359
Available from: 2014-04-27 Created: 2014-04-27 Last updated: 2015-02-03Bibliographically approved
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.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1193
Magnetic biosensor, magnetic nanoparticle, DNA detection
National Category
Nano Technology Biochemistry and Molecular Biology Condensed Matter Physics
Research subject
Engineering Science
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)
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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Bejhed, Rebecca StjernbergStrömberg, MattiasNilsson, MatsStrömme, MariaSvedlindh, Peter
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