Biomimetic Control of Size in the Polyamine‐Directed Formation of Silica Nanospheres

Sumper, Manfred; Lorenz, Sonja; Brunner, Eike

doi:10.1002/anie.200352212

Cited by 191 publications

(199 citation statements)

References 22 publications

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“…In this system neither LCPA nor any of the three T. pseudonana silaffins alone was able to induce silica formation, yet mixtures of LCPA and silaffins exhibit silicaforming activity. This is consistent with previous observations demonstrating that supramolecular assemblies of polyamines and polyvalent anions lead to rapid silica precipitation (5,16,17). Interestingly, when the silica precipitation activities were analyzed as a function of the silaffin concentration in the presence of a constant amount of LCPA, the result was markedly different for each silaffin-LCPA assembly (Fig.…”

Section: Silica Formation By Silaffin-lcpa Assembliessupporting

confidence: 92%

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Silica Morphogenesis by Alternative Processing of Silaffins in the Diatom Thalassiosira pseudonana

Poulsen

Kröger

2004

Journal of Biological Chemistry

241

364

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For almost 200 years scientists have been fascinated by the ornate cell walls of the diatoms. These structures are made of amorphous silica, exhibiting species-specific, mostly porous patterns in the nano-to micrometer range. Recently, from the diatom Cylindrotheca fusiformis unusual phosphoproteins (termed silaffins) and long chain polyamines have been identified and implicated in biosilica formation. However, analysis of the role of silaffins in morphogenesis of species-specific silica structures has so far been hampered by the difficulty of obtaining structural data from these extremely complex proteins. In the present study, the five major silaffins from the diatom Thalassiosira pseudonana (tpSil1H, -1L, -2H, -2L, and -3) have been isolated, functionally analyzed, and structurally characterized, making use of the recently available genome data from this organism. Surprisingly, the silaffins of T. pseudonana and C. fusiformis share no sequence homology but are similar regarding amino acid composition and posttranslational modifications. Silaffins tpSil1H and -2H are higher molecular mass isoforms of tpSil1L and -2L, respectively, generated in vivo by alternative processing of the same precursor polypeptides. Interestingly, only tpSil1H and -2H but not tpSil1L and -2L induce the formation of porous silica patterns in vitro, suggesting that the alternative processing event is an important step in morphogenesis of T. pseudonana biosilica.During evolution many organisms (e.g. diatoms, sponges, radiolaria) have acquired the ability to use the ubiquitous monosilicic acid Si(OH) 4 for the formation of species specifically structured, silica-based exo-or endoskeletons (1). This interesting biomineralization phenomenon is mediated by cellular organic (macro-) molecules that accelerate silicic acid polycondensation and control morphogenesis of the forming silica (2). Diatoms are an extremely large group (Ͼ10,000 species) of unicellular eukaryotic algae that play a major role in biological silica cycling. Within the last few years diatom biosilica-associated proteins (termed silaffins) and long chain polyamines (LCPA) 1 have been identified and hypothesized to represent key components of the diatom biosilica-forming machinery. Silaffins and LCPA exhibit the remarkable ability to induce rapid silica deposition in vitro and to control the nanostructure of the forming silica (3). Therefore, unraveling the correlations between chemical structures, physical properties, and silica-forming activities of silaffins and LCPA will be important for understanding the molecular mechanism of species-specific biosilica nanopatterning. So far, silaffins have only been characterized from the diatom Cylindrotheca fusiformis. They are highly modified proteins/peptides rich in hydroxyamino acids (serine, threonine, hydroxyproline) and lysine residues. Silaffins natSil1A and -1B are O-phosphorylated at numerous sites and contain polyamine-modified lysine residues, features that enable these peptides to rapidly form silica nanospheres in vitr...

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Section: Silica Formation By Silaffin-lcpa Assembliessupporting

confidence: 92%

“…phosphate) and LCPA mediate the formation of silica spheres with diameters ranging from 50 to 900 nm (7,16). This is also the case with T. pseudonana LCPA.…”

Section: Silica Formation By Silaffin-lcpa Assembliesmentioning

confidence: 77%

Silica Morphogenesis by Alternative Processing of Silaffins in the Diatom Thalassiosira pseudonana

Poulsen

Kröger

2004

Journal of Biological Chemistry

241

364

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“…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.…”

Section: Polymer : Si Ratiomentioning

confidence: 99%

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

et al. 2017

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Silicon is among the most abundant elements on the Earth. It occurs in many minerals and plays an important role in several biochemical processes. Some living organisms use silicon dioxide as a substrate for building elements of their bodies. Unicellular diatom algae build frustules from silicon dioxide. The skeleton of siliceous sponges is a silicaprotein composite. Similarly, rice hulls which protect seeds, contain silica as an important component. The living organisms assimilate silicon from the environment in the form of silicic acid. However, the biochemical mechanisms involved in the transformation of silicic acid to solid siliceous materials are still poorly understood.Evidently, condensation of silicic acid in the living organisms proceeds under control of biopolymers and it is important to know how various types of polymers influence the condensation. Bio-inspired chemistry involving the interaction between polymeric silicic acid and functional polymers results in interesting composite materials, including nanoparticles and bulk materials. This review contains a brief description of the mechanism of silicic acid condensation in aqueous medium and also includes a discussion on various precursors of silicic acid. The main focus of the review is on the influence of polymers bearing nitrogen and oxygen-containing functional groups on silicic acid condensation starting from monomer to three-dimensional polymer. Influence of molecular weight of the organic polymer on the condensation and structure of the resulting product is also elaborated. The biological importance of the obtained data and strategies for novel applications of the synthesized composite materials are described in the concluding section of the review. The biomimetic condensation processes open up new vistas for development of novel materials and applications in the biomedical and process industries.

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“…[94] Die silicatreichen Zellwände der Diatomeen werden durch spezielle Peptide in Form des Silaffins [137] und Polyamins [138] zusammengehalten. Ein genaues Verständnis der Zellwandstruktur solcher Kieselalgen könnte z.…”

Section: Membranproteineunclassified

Festkörper‐NMR‐Spektroskopie an komplexen Biomolekülen

2010

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Biomolekulare Anwendungen der NMR‐Spektroskopie werden oft mit löslichen Molekülen oder Magnetresonanztomographie in Verbindung gebracht. Seit Ende der 70er Jahre liefert darüber hinaus die Festkörper‐NMR‐Spektroskopie (FK‐NMR) auf atomarer Ebene Einblicke in komplexe biomolekulare Systeme von Lipid‐Doppelschichten bis hin zu Biomaterialien. Im letzten Jahrzehnt haben Fortschritte im Bereich der NMR‐Spektroskopie, der Biophysik und der Molekularbiologie das Repertoire der FK‐NMR‐Spektroskopie für biomolekulare Studien erheblich erweitert. Dieser Aufsatz behandelt neueste Ansätze und deren methodische Herausforderungen und diskutiert Fortschritte bei der Anwendung der FK‐NMR‐Spektroskopie im Grenzgebiet von Struktur‐ und Zellbiologie.

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Biomimetic Control of Size in the Polyamine‐Directed Formation of Silica Nanospheres

Cited by 191 publications

References 22 publications

Silica Morphogenesis by Alternative Processing of Silaffins in the Diatom Thalassiosira pseudonana

Silica Morphogenesis by Alternative Processing of Silaffins in the Diatom Thalassiosira pseudonana

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

Festkörper‐NMR‐Spektroskopie an komplexen Biomolekülen

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