Dresden 2014 – scientific programme

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MA: Fachverband Magnetismus

MA 19: Poster I

MA 19.11: Poster

Tuesday, April 1, 2014, 13:00–15:30, P1

Rapid thermoreversible formation of ordered monolayers of superparamagnetic beads interconnected by DNA bridges — •Marianne Bartke, Bernhard Eickenberg, Frank Wittbracht, and Andreas Hütten — Department of Physics, Thin Film and Physics of Nanostructures, University of Bielefeld, D-33615 Bielefeld, Germany

Superparamagnetic beads have numerous applications within microfluidic systems, where they can be used to serve as mobile substrates, bind, transport and separate analytes or as magnetic labels. Recently, the use of beads as self-assembling matter has attracted attention. Under the influence of a rotating homogeneous magnetic field, beads rapidly form ordered monolayers. In the absence of a magnetic field, the cluster structures rapidly disassemble. In this work, a method to prevent the decay of the monolayers in the absence of a magnetic field has been found. The decay is prevented by DNA double strand *bridges* that connect adjacent particles. If the bead surface has been prepared with a streptavidin coating, DNA can be linked to the beads with biotin. The beads are then covered with a layer of DNA strands. These strands are complementary to a linker-DNA. When the linker is added DNA single strands turn (hybridize) into DNA double strands. The hybridization between the linker strands and the oligonucleotides on the surface of the beads leads to a solidification of the monolayer, which originally has been produced and stabilized by the external rotating magnetic field. The DNA bridges can be broken and assembled through controlled temperature change.