Although silica nanoparticles are believed to be non-toxic, the unique physicochemical properties of nanosilica (also known as nanoparticulate silicon dioxide) that have made them attractive for the industry may bring potential hazards to human health. Nanosilica is rapidly becoming a part of our daily life and is produced on an industrial scale as additives to cosmetics, drugs, printer toners and foods. Functionalized nanoparticulate silicon dioxide is being applied in biotechnology and biomedicine in drug delivery systems, in cancer therapy, for enzyme immobilization and for DNA transfection. Their specific surface characteristics, porosity and capacity for functionalization make them good tools for biomolecule detection and separation, providing solid media for drug delivery systems and acting as contrast agent protectors. In coatings applications they provide improved scratch and abrasion resistance, corrosion-resistance and super-hydrophobic and easy-clean properties.
COSMETICS: Silica nanoparticles are used in a variety of cosmetics, including hair, skin, lip, nail and face products. They are utilized in emulsion systems to facilitate the delivery of active ingredients. Silica nanoparticles contribute to the stability of active ingredients within formulations and control and improve the delivery mechanism.
MEDICINE: Nanosized mesoporous silica particles with high colloidal stability are being developed as drug delivery systems for targeted cancer treatment and as bioimaging devices. They are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Silica nanoparticles feature a well-defined and tunable porosity at the nanometre scale, high loading capacity, and multiple functionality for targeting and entering different types of cells. The structure, morphology, size, and surface properties of the nanoparticles are tunable for the purposes of drug loading, controlled drug release and delivery that deliver therapeutic agents to the target site in a controlled manner. Leonardo Biosystems utlizies nanosilica in a multistage drug delivery platform (MSV™) focused on the treatment of metastatic cancers.1 The first stage consists of a silicon nanoparticle that is rationally designed to circumvent the multiple biological barriers in the bloodstream, and concentrate near cancer cells.
COATINGS: Silica nanoparticles are applied in a variety of industrial coating applications and high performance exterior paints. Depositing hydrophilic silicon dioxide nanolayers on various substrates (e.g. steel, aluminum, plastics, glass) give the surface functional characteristics such as easy-clean, anti-dirt, anti-fog and anti-drip. The coating are completely transparent and has no impact on the visual appearance of the substrate. Silica nanoparticles can provide improved scratch and abrasion resistance in coatings. Micro hardness, storage modulus and temperature resistance are increased by these coatings and they also offer transparency. They have been applied in automotive finishes. Evonik Degussa supplies a number of nanoparticle silica coatings products.2 Altana is also prominent in this sector.3
FOOD: Synthetic amorphous silica (SAS) has been widely applied in food products as a food additive (E551) for several decades. In food it is food used as an anti-caking agent or carrier of flavours. SAS is a nanostructured material composed of aggregates of primary particles in the lower nanometer size range. Silicon dioxide nanoparticles are also used in used in food contact surfaces and food packaging applications
COMPOSITES: Surface-modified silica nanoparticles have been utlized as concentrates in epoxy resins to improve many different properties, including strength, modulus, toughness, and fatigue performance for application in automotive composites and machine parts. They have also been incorporated into cement products for reduced porosity and improved stability.
2. Silica-Nanocomposites, www.tego.de/sites/dc/Downloadcenter/Evonik/Product/Tego/en/Technical-Background/technical-background-nanocomposites.pdf