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| Properties of MagQu's Bio-Functionalized Magnetic Beads |
| Some important properties of bio-functionalized magnetic beads dispersed in PBS solution are described. |
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Superparamagnetism |
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 Due to magnetic Fe3O4 core, magnetic beads possess permanent magnetism. When these magnetic beads are dispersed in solvents such as PBS solution, the magnetic domain of each individual magnetic bead directs equally to all directions. Thus, no resultant magnetic moment is generated by magnetic beads under zero magnetic field. When an external magnetic field is applied, magnetic domains of magnetic beads tend to align along the external magnetic field, in turns, a non-zero magnetic moment is generated with magnetic beads. As the external magnetic field is removed, due to Brownian motion, the orientated magnetic domains of magnetic beads relax, and direct equally all direction. So that the magnetic moment of magnetic beads vanishes when the external magnetic field is removed. This is so-called superparamagnetism. A typical magnetic hytereristic curve of superparamagnetic magnetic beads dispersed in solution is shown. Clearly, the magnetic moment M is zero under zero field (H = 0).
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Stability |
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MagQu warrants the validity of Type I and Type II magnetic beads for 6 months when the magnetic beads in PBS solution are stored at 4 - 20oC.
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Toxicity |
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MagQu's magnetic fluids having magnetic-bead concentration lower than 10-5 M are non-toxic to cells or biomolecules.
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Bead size distribution |
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 By using magnetic force microscope to analyze the sizes of magnetic beads, the standard deviation for the size distribution of magnetic beads (Type I - III) is less than 5 %. For example, for a sample having a mean diameter of 29.3 nm, the standard deviation of the bead diameter is 1.4 nm.
Ref.:
"Nanomagnetic particles for SQUID -based magnetically labelled immunoassay", IEEE Trans, Supercord, 15, 668 (2005).
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