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Blu-ray optomagnetic measurement based competitive immunoassay for Salmonella detection
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, Solid State Physics.
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, Solid State Physics.
2016 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 77, p. 32-39Article in journal (Refereed) Published
Abstract [en]

A turn-on competitive immunoassay using a low-cost Blu-ray optomagnetic setup and two differently sized magnetic particles (micron-sized particles acting as capture particles and nano-sized particles acting as detection particles) is here presented. For Salmonella detection, a limit of detection of 8 x 10(4) CFU/mL is achieved within a total assay time of 3 h. The combination of a competitive strategy and an optomagnetic setup not only enables a turn-on read-out format, but also results in a sensitivity limit about a factor of 20 times lower than of volumetric magnetic stray field detection device based immunoassays. The improvement of sensitivity is enabled by the formation of immuno-magnetic aggregates providing steric hindrance protecting the interior binding sites from interaction with the magnetic nanoparticle labels. The formation of immuno-magnetic aggregates is confirmed by fluorescence microscopy. The system exhibits no visible cross-reaction with other common pathogenic bacteria, even at concentrations as high as 10 CFU/mL. Furthermore, we present results when using the setup for a qualitative and homogeneous biplex immunoassay of Escherichia coli and Salmonella typhimurium.

Place, publisher, year, edition, pages
2016. Vol. 77, p. 32-39
Keyword [en]
Biosensors; Immunoassays; Magnetic particles; Magneto-optics
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-264720DOI: 10.1016/j.bios.2015.08.070ISI: 000366766900006OAI: oai:DiVA.org:uu-264720DiVA, id: diva2:861185
Funder
Swedish Research Council Formas, 221-2012-444
Available from: 2015-10-15 Created: 2015-10-15 Last updated: 2018-03-13Bibliographically approved
In thesis
1. Magnetic Nanoparticle Based Biosensors for Pathogen Detection and Cancer Diagnostics
Open this publication in new window or tab >>Magnetic Nanoparticle Based Biosensors for Pathogen Detection and Cancer Diagnostics
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes several magnetic nanoparticle (MNP)-based biosensing strategies which take advantage of different magnetic sensors, molecular tools and nanotechnologies. Proposed biosensors can be classified into three groups, i.e., immunoassay-based, molecular amplification-based, and nanoparticle assembly-based. The principal motivation is to develop and optimize biosensors for out-of-lab and point-of-care testing.

Immunoassay-based biosensors described in this thesis employ antibodies as the bio-recognition element for the detection of bacteria cells/fragments or proteins. Two typical immunoassay formats, i.e., direct and competitive format, are studied and compared for bacteria detection. In addition, in the protein biomarker detection, MNP chains are formed in the presence of target analytes as well as in the external rotating magnetic field. The high shape/magnetic anisotropy of the chains provides better optomagnetic performance.

Two different molecular amplification methods, i.e., rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP), are described under the topic of molecular amplification-based biosensors. In RCA-based biosensors, DNA probe modified MNPs bind to the amplicons after amplification. In LAMP-based biosensors, MNPs are either modified with primers that keep growing during the amplification, or are co-precipitated with the by-product (Mg2P2O7) of the amplification.

The design of the nanoparticle assembly-based biosensors described in this thesis is based on duplex-specific nuclease (DSN)-assisted target recycling and core-satellite magnetic superstructures. In the presence of target microRNA, DSN cuts the DNA scaffold of the core-satellite assembly, releasing MNP satellites that can be quantified by the sensor.

Different kinds of target analytes, i.e., pathogens or cancer biomarkers, are detected at the aiming for rapid, low-cost and user-friendly diagnostics.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 55
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1647
Keyword
Magnetic biosensors, magnetic nanoparticles, homogeneous assays, volumetric sensing
National Category
Other Engineering and Technologies not elsewhere specified
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-346014 (URN)978-91-513-0278-2 (ISBN)
Public defence
2018-05-04, Häggsalen, Ångströmlaboratoriet, Lägerhyddsv. 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2018-04-13 Created: 2018-03-13 Last updated: 2018-04-24

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