particles, the nucleic acid binding capacity and ways to determine it, and the composition of the silica particles regarding the comprised SiO$_{2 }$ and core particles are described above and it is referred to the above disclosure which also applies here. Non-limiting embodiments are again briefly described in the following. 

According to one embodiment, the silica particles are capable of binding at least 12.5 µg nucleic acid molecules per mg particles, at least 15 µg nucleic acid molecules per mg particles or at least 17 .5 µg nucleic acid molecules per mg particles. As is shown by the examples, the silica particles of the present invention are even capable of binding at least 20 µg nucleic acid molecules per mg particles. This extraordinary high nucleic acid binding capacity is an important advantage over prior art silica particles. As described above, according to one embodiment, the nucleic acid binding capacity of the particles is determined as described in example 6. 

The porous silica particles may comprise macropores. According to one embodiment, the surface of the particles additionally comprises micropores. Micro- and macropores can be determined as described by IUPAC (see above). According to one embodiment, the particles have a size of 25 µm or less, 20 µm or less, 15 µm or less, 10 µm or less, 5 µm or less or 3 µm or less. Suitable size ranges are also described above. The silica particles may have a size that lies within the range of 50 nm to 25 µm, 100 nm to 10 µm, 100 nm to 5 µm or 250 nm to 3 µm. 

According to one embodiment, the porous silica particles have a composition regarding the comprised SiO$_{2 }$ and core particles that is 20 to 50% (by weight) core particles and about 50 to 80% (by weight) SiO$_{2}$ , preferably 25 to 50% (by weight) core particles and about 50 to 75% (by weight) SiO$_{2 }$ (see also above). According to one embodiment, the silica particles have an unmodified silica surface. 

According to one embodiment, the contained core par› ticles have magnetic properties. E.g. the core particles may have superparamagnetic, paramagnetic, ferromagnetic or ferrimagnetic properties. Suitable materials were described in detail above. According to one embodiment, the particles comprise iron oxide, preferably magnetite and/or maghemite as core particles. According to one embodiment, the core particles, which preferably are magnetic, have a diameter that lies in a range selected from 8 to 150 nm, 10 to 100 nm and 10 nm to 60 nm. 

As described, the silica particles according to the second aspect are obtainable by the method according to the first aspect. Details with respect to said method according to the first aspect are described above, and it is referred to the above disclosure. The particles are due to their high nucleic acid binding capacity preferably used for isolating nucleic acids. 

Use of the Particles 

According to a third aspect, the present disclosure per› tains to the use of silica particles produced according to the method according to the first aspect or the use of silica particles according to the second aspect, for isolating biomolecules, in particular for isolating nucleic acids from various samples. 

The particles produced with the method according to the present invention as well as the particles according to the second aspect can be used basically in all fields in particular all fields of life science, including but not limited to the isolation of biomolecules, biological materials such as cells or cell organelles, analytical, forensic, diagnostic or medical applications. 

The silica particles obtained by the method according to the present invention have a high capacity to bind biomol› ecules such nucleic acids, thereby making the particles of this invention especially useful for isolating or separating biomolecules such as nucleic acid molecules from various samples and mixtures. The biomolecule to be isolated may be selected from the group consisting of nucleic acids, proteins, polypeptides, peptides, carbohydrates, lipids, and combinations thereof. In particular, the particles produced according to the present invention are suitable for isolating nucleic acids. 

Subsequently, the use of the particles produced by the method of the invention for isolating nucleic acids from samples will be described in further detail. The term "sample" in this respect is used in a broad sense and is intended to include a variety of sources that contain nucleic acids. The sample may be a biological sample but the term also includes other, e.g. artificial samples which comprise nucleic acids such as in vitro reaction mixtures that contain nucleic acids, such as polymerase chain reactions (PCR), nucleic acid sequencing reactions, restriction endonuclease or other nuclease digestion reactions, nucleic acid hybrid› ization assay mixture, in vitro transcription and/or transla- tion assay mixtures and amplification reactions. Preferably, the sample is a biological sample. Exemplary biological samples include, but are not limited to, tissues, including but not limited to, liver, spleen, kidney, lung, intestine, brain, heart, muscle, fat, pancreas, cells, cell cultures, body fluids in general; whole blood; serum; plasma; red blood cells; white blood cells; buffy coat, tumor cells, fetal cells, host and graft cells; swabs, including but not limited to buccal swabs, throat swabs, vaginal swabs, urethral swabs, cervical swabs, throat swabs, rectal swabs, lesion swabs, abscess swabs, nasopharyngeal swabs, and the like; urine; sputum; saliva; semen; lymphatic fluid; liquor; anmiotic fluid; cere› brospinal fluid; peritoneal effusions; pleural effusions; fluid from cysts; synovial fluid; vitreous humor; aqueous humor; bursa fluid; eye washes; eye aspirates; pulmonary lavage; lung aspirates; bone marrow aspirates, cells in suspension, as well as lysates, extracts, or materials obtained from any cells and microorganisms and viruses that may be present on or in a sample and the like. Materials obtained from clinical or forensic settings that contain nucleic acids are also within the intended meaning of the term biological sample. Fur› thermore, the skilled artisan will appreciate that lysates, extracts, or materials or portions thereof obtained from any of the above exemplary samples are also within the scope of the term sample. Preferably, the sample is a biological sample derived from a human, animal, plant, bacteria or fungi. It may be of prokaryotic or eukaryotic origin. In particular, the term "sample" refers to a nucleic acid con› taining sample which also comprises cells. Preferably, the sample is selected from the group consisting of cells, tissue, body fluids such as for example blood, blood products such as buffy coat, plasma and serum, urine, liquor, sputum, stool, CSF and sperm, epithelial swabs, biopsies, bone marrow samples and diverse tissue samples. The biological sample may be preserved and e.g. may be contained in preservative medium. E.g. the sample from which the nucleic acids are to be isolated may have been stored in a preservative, including but not limited to paraffin-embedded tissue samples and cellular and tissue or cell samples stored in a liquid-based cytology medium such as SUREPATHfi or PRESERV- CYTfi. Also other biomolecules such as e.g. proteins can be isolated from the samples mentioned above which comprise the respective biomolecule of interest. 

