Monodisperse Silica Microspheres from microParticles GmbH up to 25 µm
Silica particles in the nanometer as well as micrometer diameter range find an increasing use in medical diagnostics, in the pharmaceutical industry, in biotechnology and molecular biology, sensor technique, materials sciences, colloid research, and others. Sol-gel processes that were established already at the end of the 1960s by Stöber and coworkers allow for the rather convenient preparation of monodisperse silica particles in the size range from 100 nm to 3µm. So far, attempts that were made to utilize these processes for the manufacture of silica microspheres in the micrometer diameter range above 3 µm failed. This was mainly due to the barely controllable balance between nucleation and growth on one hand and reduced colloidal stability on the other. As a consequence, often dumbbells, irregularly-shaped particles, and heavily broadened particle size distribution are yielded. In the market, monodisperse silica particles in the micrometer diameter range above 3 µm are either rarely found or the offered materials show broad size distribution with CV values of about 20-30 %. Recently, we have successfully developed a modified sol-gel strategy for the preparation of monodisperse silica microspheres in the diameter range up to 8 µm. By further developments of this process, a considerably extended range of high-quality silica particles above 8 µm up to 25 µm could be achieved. The manufactured particles possess the following properties:
- Narrow particle size distributions (CV < 5 %).
- Spherical shape.
- Smooth surface.
- High optical tranparency.
- High mechanical and thermal stability.
- Hydrophilic surface properties.
- Density: 1,85 g/cm3.
- Refractive index: 1,42.
- Available in a wide diameter range up to 25 µm
The Silica-microspheres come as 5 wt.-% aqueous dispersions or in dry powder form. They can be used in a number of applications, such as isolation of nucleic acids, purification of biomolecules, preparation of hollow capsules, or in particle-based immunoassays.