Biomagnetism at UU and MdH

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Biomagnetism at UU and MdH
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The Group
Dept. Engineering Sciences, UU Professor Peter
Svedlind Ph D Klas Gunnarsson PhD student
Stojanka Bijovic Dept. Surface Biotechnology, UU
and MdH Professor Sven Oscarsson PhD student
LarsErik Johansson
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Biomagnetism

• Controlled motion of magnetic beads on patterned
  surfaces

• J. Appl. Phys. 96, 2901-2908 (2004)
• J. Magn. Magn. Mater. 280, 202-207 (2004)
• Advanced Materials, submitted 2004
• Work by others
• Microelectromagnetic matrix with Au wires
• Westervelt et al., Harvard University
• Assembling of beads using magnetic elements
• microwells
• Yellen and Friedman, Drexel University

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Motion of single magnetic beads
Magnetic elements defined by electron lithography
MFM
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Experimental setup
Bead size 2.8 mm, element size 2 x 6 mm
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Transportation lines
Happ

Optical images
Always jumps from a demagnetized side to a
magnetized tip of an ellipse
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Junctions

• Junctions can be added to transport lines
• Programmable motion
• Separation of particles
• Real-time analysis

fast
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Something about beads
Microspheres contain 10-60 magnetite A
ferrofluid (magnetite)/ styrene/divinylbenzene
mixture is dispersed in water and
suspension- polymerized to trap the magnetite in
the polymer matrix. The magnetite is dispersed
throughout the beads. Derivatization by
pH- control.
Polystyrene beads http//www.dynal.no/
Encapsulated beads - these have a magnetite-rich
core polymer shell, with COOH and NH2
functional groups.
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Dynabeads MyOne 1 micron beads
Smaller beads accelerate process speed in
e.g. Immunoassay applications
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Different types of beads I

• Polystyrene beads
• hydrophobic adsorption of
  biomolecules
• uniform in size
• spherical in shape
• 10-60 iron oxide
• Polysaccharide beads, made by coating aggregates
  of iron oxide with a polysaccharide like dextran
  (nanomag -D http//www.micromod.de/)
• hydrophilic covalent bonding of
  biomolecules possible
• smaller size possible, 0.05 0.5 mm
• 75-80 iron oxide
• not as monodisperse as polystyrene beads
• not as spherical as polystyrene beads

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Different types of beads II

• Silica beads, magnetite nanoparticles in SiO2
  matrix, homogeneous distribution (sicastar -M
  http//www.micromod.de/)
• monodisperse 1.5 mm beads
• hydrophilic surface
• Polystyrene beads coated with CrO2 film,
  ferromagnetic beads
• (http//www.spherotech.com/)
• average size in range 2-10 mm
• not so monodisperse
• carboxyl or amino functional groups

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Magnetic nanoparticles http//www.nanomat.com/
Co nanoparticles
Fe nanoparticles 8 nm, 96m2/g
Fe-Co nanoparticles, high Ms 120 nm, 6 m2/g
g-Fe2O3 nanoparticles
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Why ferromagnetic (stable magnetic moment) beads?
Nano-switch for biochemical processes
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Some near future studies

• Basic scientific studies on magnetic
  microstructure
• Hemispherical derivatization of magnetic beads
  by
• photolytic de-protection of photo-cleavable
  groups
• (NVOC, nitroveratryloxycarbonyl) immobilised via
• amino-groups on beads
• Transportation of magnetic beads in different
• environments, e.g. blood serum
• Derivatization of beads with antibodies (iGE)
• and antigenes used in diagnostic tests of
  allergic
• reactions
• Biosensor-principle based on ac susceptibility
  studies