title: Homogeneous Protein Analysis by Magnetic Core-Shell Nanorod Probes.
abstract: Studying protein interactions is of vital importance both to fundamental biology research and to medical applications. Here, we report on the experimental proof of a universally applicable label-free homogeneous platform for rapid protein analysis. It is based on optically detecting changes in the rotational dynamics of magnetically agitated core-shell nanorods upon their specific interaction with proteins. By adjusting the excitation frequency, we are able to optimize the measurement signal for each analyte protein size. In addition, due to the locking of the optical signal to the magnetic excitation frequency, background signals are suppressed, thus allowing exclusive studies of processes at the nanoprobe surface only. We study target proteins (soluble domain of the human epidermal growth factor receptor 2 - sHER2) specifically binding to antibodies (trastuzumab) immobilized on the surface of our nanoprobes and demonstrate direct deduction of their respective sizes. Additionally, we examine the dependence of our measurement signal on the concentration of the analyte protein, and deduce a minimally detectable sHER2 concentration of 440 pM. For our homogeneous measurement platform, good dispersion stability of the applied nanoprobes under physiological conditions is of vital importance. To that end, we support our measurement data by theoretical modeling of the total particle-particle interaction energies. The successful implementation of our platform offers scope for applications in biomarker-based diagnostics as well as for answering basic biology questions.
authors.affiliation: Molecular Diagnostics, AIT Austrian Institute of Technology , Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schrittwieser
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg , Marburg, Germany.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Pelaz
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg , Marburg, Germany.|CIC Biomagune , San Sebastian, Spain.
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
authors.affiliation: Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse; INSA, UPS, CNRS , Toulouse, France.
authors.forename: Sergio
authors.initials: S
authors.lastname: Lentijo-Mozo
authors.affiliation: Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse; INSA, UPS, CNRS , Toulouse, France.
authors.forename: Katerina
authors.initials: K
authors.lastname: Soulantica
authors.affiliation: Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig , Braunschweig, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Dieckhoff
authors.affiliation: Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig , Braunschweig, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Ludwig
authors.affiliation: Electron Microscopy for Materials Research (EMAT), University of Antwerp , Antwerp, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Altantzis
authors.affiliation: Electron Microscopy for Materials Research (EMAT), University of Antwerp , Antwerp, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: Bals
authors.affiliation: Molecular Diagnostics, AIT Austrian Institute of Technology , Vienna, Austria.
authors.forename: Joerg
authors.initials: J
authors.lastname: Schotter
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008280:Magnetics; D008958:Models, Molecular; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D011485:Protein Binding; D060066:Protein Interaction Maps / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D000068878:Trastuzumab / Q000737:chemistry* / Q000627:therapeutic use
chemical_list: D055910:Antibodies, Immobilized; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human
keywords: anisotropic polarizability; core−shell nanorod; dispersion stability; homogeneous measurement; magnetic nanoparticle; protein analysis; surface functionalization