| 摘要 |
The invention relates to magnetic particles coated with silica (Si02), whereby the silicate layer is closed and tight and is characterized by having an extremely small thickness on the scale of a few nanometers—hereafter also referred to as a silica nanolayer. This invention also relates to an improved method for producing these silicate-containing magnetic particles that, in comparison to the prior art, lead to a product having a closed silicate layer and thus entail a highly improved purity. In addition, the novel method prevents an uncontrolled formation of aggregates and clusters of silicates on the magnetite surface, thereby having a positive influence on the properties and biological applications cited below. The novel method also enables the depletion of nanoparticulate solid substance particles on the basis of a fractionated centrifugation. The inventive magnetic particles exhibit an optimized magnetization and suspension behavior as well as a very advantageous run-off behavior from plastic surfaces. These highly pure magnetic particles coated with silicon dioxide are preferably used for isolating nucleic acids from cell and tissue samples, whereby the separating out from a sample matrix ensues by means of magnetic fields. These particles are particularly well suited for the automatic purification of nucleic acids, mostly from biological body samples for the purpose of analyzing them with different amplification methods.
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