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Biosilicifieation (formation of biosilica) has become an exciting source of inspiration for the development of novel bionic approaches.Silica is an important material in nanotechnology.Conventional procedures for the production of silica require high temperatures and extremes of pH.diatoms,sponges and higher plants are able to form their silica skeleton under ambient (low temperature and near-neutral pH.) conditions.Siliceous sponges are unique among these organisms in their ability to catalyze silica formation using a specific enzyme:silicatein.This enzyme shows both silica esterase activity and silica polymerase activity.The hydroxyl group of the serine residue and the imidazole group of the histidine residue in the catalytic center of the silicatein molecule are the crucial moieties involved in the catalytic mechanism of the enzyme.Monomeric silicatein is able to self-assemble to long filaments which are able to biosilicify.The recombinant silicatein (protected by patents; EP 1320624; US 7,169,589B2) is of great interest for a variety of medical and technical applications.First strategies towards the application of the enzyme for surface modification (coating) of biomaterials have been developed.Silicatein is not only able to catalyze the polycondensation of biosilica but also the synthesis of other metal oxides used as semiconductors or catalysts.Immobilization of His-tagged silicatein onto nanowires has been used for the fabrication of functional,spicule-like core-shell materials with alternating metal oxide layers.Biosilica-modified surfaces are bioactive and enhance osteoblast function.Such surfaces may be of interest as coatings of medical implants to promote new bone formation.The discovery of silintaphin-1 which forms the "core" of the silicatein filaments of the sponge spicules markedly extends the application range of silicatein.Silintaphin-1 has structure-directing activity:it directs the assembly of silicatein molecules or silicatein immobilized on functionalized metal oxide particles to filamentous or rigid nanostructures.The combined action of silintaphin-1 and silicatein makes biocatalytic formation of light-transmitting biomimetic optical fibres feasible.Recent advances in soft lithography demonstrate that the sponge enzymes and proteins involved in biosilica formation may also be of interest for the generation of nanopatterned layers of silica in microelectronics.