In colloidal silica the particles are very finely divided and are distributed uniformly in a solid, liquid, or gas. An alternative termi is silica sol.
A number of different approaches and suggestions could be used in answering the question which materials can be classified as nanomaterials. A very basic definition is that nanotechnology is concerned with structures and objects of size between 1 nm and 100 nm in at least one dimension.However, many institutions, researchers, and authorities specify different sizes, and no single uniform and universally applicable definition currently exists.
Nanostructured materials are those with a nanoscale structure within the material or at its surface.
Nanotechnology is a collective term for a large number of innovations and developments whose common denominator is the investigation, production, and application of very small structures.
When a substance is resorbed this means that it enters the blood circulation.
Silica is the common name for silicon dioxide (SiO2). In German, it is often called “Kieselsäure” (silicic acid). SiO2 is very common in nature, for example, as quartz in rocks or as grains of sand. This mineral is also useful for plants and animals, as it gives horsetail grass its stability, for example. Evonik produces only synthetic amorphous silica, or SAS. The various types of silica produced by Evonik differ in terms of their characteristic features, such as particle size or surface treatment. This creates different properties for many different applications.
Silica types with crystalline and amorphous structure are found in nature and are also produced synthetically.
Quartz e.g. is a crystalline silica, whereas the silica which is incorporated in plants is amorphous. The structure of this incorporated silica can look very similar to the structure of Synthetic Amorphous Silica (SAS). While crystalline silica has an orderly lattice structure, amorphous silica is unstructured. Consequently, it differs from crystalline SiO2 not only in physical terms but also as regards its toxicological properties. There are no hazards associated with amorphous silica.