title: A microfluidic, dual-purpose sensor for in vitro detection of Enterobacteriaceae and biotinylated antibodies.
abstract: In this paper, we present a versatile, dual-purpose sensor for in vitro detection of Enterobacteriaceae (e.g. Escherichia coli) and biotinylated antibodies (e.g. IgG rabbit polyclonal antibodies), based on different detection principles for each bioanalyte. These bioanalytes are tagged individually with functionalized magnetic microparticles, suspended into a static fluid and injected into a microfluidic channel. Without the need for bulk or complicated pumping systems, the functionalized microparticles are set in motion by a magnetic force exerted on them by integrated microconductors. The fundamental detection principle is the decrease in the velocity of the microparticles that are loaded with the respective bioanalyte, due to factors inhibiting their motion. The velocity of the unloaded, bare microparticles is used as a reference. We discovered a novel mechanism on which the constrained particle motion is based; in the case of E. coli, the inhibiting factor is the enhanced Stokes' drag force due to the greater volume and altered hydrodynamic shape, whereas in the case of biotinylated antibodies, it is the increased friction force at the interface between the modified microparticle and the biosensor's surface. Friction force is for the first time employed in a scheme for resolving biomolecules. Integrated magnetic microsensors are used for the velocity measurements by detecting the microparticles' stray field. Moreover, we developed a biocompatible, easy to implement and reliable surface modification that practically diminishes the problem of bioadhesion on the sensor's surface.
authors.affiliation: Institute of Sensors and Actuators Systems, Vienna University of Technology, Gusshausstrasse 27-29, 1040 Vienna, Austria. georgios.kokkinis@tuwien.ac.at.
authors.forename: G
authors.initials: G
authors.lastname: Kokkinis
authors.affiliation: Institute of Applied Physics, Biophysics Group, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Plochberger
authors.affiliation: INESC Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Cardoso
authors.affiliation: Institute of Sensors and Actuators Systems, Vienna University of Technology, Gusshausstrasse 27-29, 1040 Vienna, Austria. georgios.kokkinis@tuwien.ac.at.
authors.forename: F
authors.initials: F
authors.lastname: Keplinger
authors.affiliation: Institute of Sensors and Actuators Systems, Vienna University of Technology, Gusshausstrasse 27-29, 1040 Vienna, Austria. georgios.kokkinis@tuwien.ac.at and Institute for Biophysics, Department of Nanobiotechnology, BOKU - University of Natural Resources and Life Sciences, Muthgasse 11/II, 1190 Vienna, Austria.
authors.forename: I
authors.initials: I
authors.lastname: Giouroudi
mesh_terms: D000906:Antibodies / Q000032:analysis* / Q000737:chemistry*; D019921:Biotinylation; D004926:Escherichia coli / Q000737:chemistry* / Q000302:isolation & purification*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
chemical_list: D000906:Antibodies; D058185:Magnetite Nanoparticles