News  2008/2009/2010
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October 2010

Particle size distribution of inorganic-organic nanohybrid particles as determined by Differential Sedimentation (CPS disc centrifuge).
Blue: SiO2-COOH-AR250, 51 nm, CV = 4,3 %;
green: SiO2-COOH-AR224, 95 nm, CV  = 3,7 %;
red: SiO2-COOH-AR234, 138 nm, CV = 4,9 %.

 

Nominal 100 nm inorganic-organic nanohybrid particles (SiO2-COOH-AR224, FE-SEM image (EMTEC Mannheim)).

Novel organically modified nanoporous silica particles in the diameter range from 30 nm up to 1000 nm

Within a BMWi-sponsored R&D project, scientists at microParticles GmbH succeeded in developing monodisperse and highly functionalized nanoporous silica particles. Compared to common silica-based products, significant progress could be made with the newly developed technology since it allows to manufacture highly monodisperse nanoparticles with diameteres far below 100 nm. The new silica-based nanoparticles possess the following features:
  • Very narrow particle size distribution (CV-values < %).
  • Spherical shape.
  • Large surface, due to the nanoporous structure of the material.
  • Excellent mechanical strength.
  • Good biocompatibility.
  • Applicable in aqueous or organic media.
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The newly developed silica-based nanoparticles can be delivered with a variety of modifications. So, the incorporation of fluorescent dyes as well as the functionalization of the particle surfaces with COOH-groups have been accomplished. Moreover, the coupling of proteins, such as streptavidin and DNA (e.g. 21-mer (dT)), is possible. From now on, these products can be delivered on request.
Potential applications of the new silica-based particles are:
  • Calibration standards in aqueous and non-aqueous media for sizing instruments and particle counters,
  • cell labeling techniques,
  • bioimaging,
  • drug delivery and release,
  • protein immobilization,
  • isolation of biotinylated molecules, and/or
  • ion exchange.

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April 2010


Optical fluorescence miroscopy of PS-MAG-Fluorescence-S2392 with green and red fluororescent label, resp.

Superparamagnetic fluorescent polystyrene particles

Intensive R&D at microParticles GmbH now led to the manufacture of monodisperse superparamagnetic polymer particles which are labeled with a number of fluorophores. Currently, particle batch PS-MAG-Fluorescence-S2392 (diameter 11.21 ±  0,41 µm, CV: 3,7 %) can be offered. Other diameters are under preparation. The particles are of spherical shape. They have a narrow size distribution, strong paramagnetism, and high fluorescence intensities. From now on, these beads can be delivered in aqueous suspensions.

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October 2009

Optical microscopy of MP-MAG-S2211 (375 µm)

New large superparamagnetic polymer beads

With our technology to manufacture iron oxide-laden polymer particles, we recently succeeded in entering the diameter range beyond 200 µm with superparamagnetic beads. Currently, one batch of superparamagnetic polymer particles is available: MP-MAG-S2211 (375 µm, C.V. 2,0 %).
The polymer beads possess strong superparamagnetic properties. They show a narrow size distribution and are of spherical shape. With immediate effect, these new polymer particles are available as aqueous suspensions or in dry powder form.

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October 2008


Particle size distribution of PS-MAG-S1702 (400 nm, CV ≤5 %) as determined by Differential Sedimentation (CPS disc centrifuge).

New nanometer scale superparamagnetic polymer particles

Within a BMWi-sponsored R&D project, microParticles GmbH now succeeded in developing monodisperse superparamagnetic polystyrene particles (PS-MAG) with 400 and 600 nm in diameter. The particles are of spherical shape and have C.V. values ≤5 %. Thus, they distinctively differ from competing products currently available in the market. Due to their high iron oxide contents of approx. 50 wt.-%, the particles show an excellent superparamagnetic behavior.
Our magnetic beads are available as plain, non-functionalized species as well as with COOH-modified surfaces. The COOH-surface functionalities are suitable for the coupling of proteins or other NH2-containing molecules. Hence, also streptavidin-modified particles (PS-MAG-SA) do belong to our product portfolio. The binding capacity with this type of beads is in the range of 3000 - 4000 pmol FITC-biotin per mg.
In the near future microParticles GmbH will be able to offer its customers also monodisperse nominal 200 nm and 300 nm superparamagnetic PS particles.

March 2008


Nominal 1µm superparamagnetic silica particles (Scanning Electron Microscopy image, by courtesy of Dr. M. Wagener, Carl Zeiss NTS GmbH.)

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.
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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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