Macromolecule mediated bioinspired silica synthesis using a diol-modified silane precursor

Abstract

Silicon isotope geochemistry is a relatively new branch of environmental change research. Here we review the recent developments in the preparation of materials, analytical methods and applications of stable silicon isotope geochemistry in the most common types of biogenic silica currently being analysed. These materials are: diatom, radiolarian and siliceous sponges in lake and ocean sediments and plant phytoliths which are preserved in soils. Despite analyses of Si isotopes being carried out on rocks and minerals since the 1950's and the increasingly widespread use of Si isotopes since the 1990's, to date only a relatively small number of studies have applied Si isotope ratios to environmental change. In lake and ocean sediments the analysis of Si isotope ratios from biogenic materials has the potential to provide an important source of palaeoenvironmental information, especially where carbonates are not preserved. In plants and soils few studies have used Si isotopes, but important advances have recently been made in the understanding within plant fractionations. These may be useful in the application of Si isotopes in phytoliths to archaeological and palaeoenvironmental contexts

Silicic acid condensation under the influence of water-soluble polymers: from biology to new materials

“…24,61,62,[65][66][67][68][69][70][71][75][76][77]98,99,[106][107][108]111,112,114,117,121,124,134,135,137,139,143,149,153,155,157 These variants exist in the case of relatively low silicon content in the system, when all PSA nanoparticles can nd chains of organic polymer. Further increase in the silicic acid content results in formation of insoluble non-uniform products 64,83 because of cross-linking by means of silicic acid which was condensed independent of the polymer control.…”

Influence of polymeric additives on biomimetic silica deposition on patterned microstructures

“…For example poly-(L-lysine) [25][26][27][28], poly-(L-arginine) [29,30], R5 peptide [31,32], amino group-containing dendrimers [33], linear oligo- [34] and poly(ethylene imine) [35,36], poly(propylene imine) [35,37], poly(allylamine) [29,[38][39][40][41][42][43][44][45], poly-(acrylic acid) [29,37,39], and poly(ethylene glycol) [2,36] have been applied. Upon addition of these polymers, usually spherical silica particles in different dimensions in the range from a few nanometers up to micrometers are formed in silica condensation experiments.…”

Regioselectively Ordered Silica Nanotubes by Molecular Templating

“…[12][13][14] Furthermore, proteins from sponges (silicatein [15] ) and diatoms (silaffins [16,17] ) were successfully applied for the in vitro polymerization of silicic acid to form biosilica analogues. [12,18] The proposed mechanism involves N-methylpropylamino groups, which are responsible for the steric fixation and catalyzed condensation of silica precursors.…”

“…2a). Because these oligopropylcellulose derivatives are soluble in water, the silica formation can be performed under mild conditions with water-soluble silica precursors, such as tetrakis(2-hydroxyethyl) orthosilicate (THEOS), [14] or by applying conventional sol-gel routes using tetraethyl orthosilicate (TEOS). Two nitrogen atoms separated by a propylene ((-CH 2 ) 3 -) group were selected as the catalytically active site for silica formation on the cellulose chain, mimicking the controlled silica deposition found in natural systems.…”

“…The organosilicon precursor (TEOS, THEOS) covering the polysaccharide chain will subsequently polycondensate to form a silica coating. Previous investigations [14] on the catalytic role of macromolecules, such as poly-(allylamine) or poly(L-lysine) hydrochloride, showed that these polymers are cationically charged in aqueous systems at neutral pH. They catalyzed the formation of spherical silica particles in the range of 200-400 nm and hexagons from 400-1000 nm from TEOS as silica precursor.…”