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March 2008
Nominal 1µm superparamagnetic silica particles
(Scanning Electron Microscopy image, by courtesy of Dr. M. Wagener, Carl Zeiss NTS GmbH.)
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Breakthrough in the development of monodisperse superparamagnetic silica particles in the 1 micron diameter range
Magnetic microspheres have found widespread applications in biochemistry, biology, biotech-nology, and medicine. Although a number of magnetic microbeads are commercially available, only few products fulfill the requirements of high magnetizability, narrow size distribution, colloidal stability, minimized nonspecific adsorption, and high bindig capacity for bioligands.
Recently, microParticles GmbH has succeeded in fabricating monodisperse spherical magnetic silica particles in the 1µm diameter range. With the newly developed method, using a modified sol-gel process, it is possible to combine strong magnetic response with high monodispersity, high colloidal stability, and high binding of bioligands. The synthesized superparamagnetic silica microspheres possess the following features:
- Narrow particle size distribution (C.V. values <5 %)
- Spherical shape.
- High magnetizability due to iron oxide loadings up to 50 wt.-%.
- Superparamagnetic properties.
- Homogeneously dispersed iron oxide nanoparticles throughout the silica matrix.
- Rapid attraction of the suspended particles by a conventional permanent magnet.
They can be used in a variety of applications like nucleic acid isolation, biomolecule purification, and particle-based immunoassays.
As from now, these superparamagnetic silica particles are available with carboxylic groups (5 wt.-% aq. suspensions) or streptavidin-modified surfaces (1 wt.-% aq. suspensions). Currently, research is underway at microParticles GmbH to develop monodisperse magnetic silica miroparticles in the submicron-size range from 200 through 1000 nm, too.
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