A solution study of silica sondensation and speciation with relevance to in vitro investigations of biosilicification

David J. Belton, Olivier Deschaume, Siddharth V. Patwardhan, Carole C. Perry

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Requiring mild synthesis conditions and possessing a high level of organization and functionality, biosilicas constitute a source of wonder and inspiration for both materials scientists and biologists. In order to understand how such biomaterials are formed and to apply this knowledge to the generation of novel bioinspired materials, a detailed study of the materials, as formed under biologically relevant conditions, is required. In this contribution, data from a detailed study of silica speciation and condensation using a model bioinspired silica precursor (silicon catechol complex, SCC) is presented The silicon complex quickly and controllably dissociates under neutral pH conditions to well-defined, metastable solutions of orthosilicic acid The formation of silicomolybdous (blue) complexes was used to monitor and study different stages of silicic acid condensation In parallel, the rates of silicomolybdic (yellow) complex formation, with mathematical modeling of the species present, was used to follow the solution speciation of polysilicic acids. The results obtained from the two assays correlate well. Monomeric Oleic acid, trimeric silicic acids, and different classes of oligomenc polysilicic acids and silica nuclei can be identified and their periods of stability during the early stages of silica condensation measured For experiments performed at a range of temperatures (273-323 K), an activation energy of 77 kJ.mol(-1) was obtained for the formation of trimers. The activation energies for the forward and reverse condensation reactions for addition of monomers to polysilicic acids (273-293 +/- 1 K) were 55.0 and 58.6 kJ.mol(-1), respectively. For temperatures above 293 K, these energies were reduced to 6 1 and 7.3 kJ.mol(-1), indicating a probable change in the prevailing condensation mechanism The impact of pH on the rates of condensation were measured There was a direct correlation between the apparent third-order rate constant for trimer formation and pH (4.7-6.9 +/- 0.1) while values for the reversible first-order rates reached a plateau at circumneutral pH. These different behaviors are discussed with reference to the generally accepted mechanism for silica condensation in which anionic silicate solution species are central to the condensation process. The results presented in this paper support the use of precursors such as silicon catecholate complexes in the study of biosilicification in vitro Further detailed experimentation is needed to increase our understanding of specific biomolecule silica interactions that ultimately generate the complex, finely detailed siliceous structures we observe in the world around us.

LanguageEnglish
Pages9947-9955
Number of pages9
JournalJournal of Physical Chemistry B
Volume114
Issue number31
DOIs
Publication statusPublished - 12 Aug 2010

Fingerprint

Silicon Dioxide
Condensation
condensation
Silica
silicon dioxide
Acids
acids
Silicon
Silicic Acid
trimers
Activation energy
silicon
Silicates
activation energy
Condensation reactions
Oleic acid
inspiration
Biocompatible Materials
Biomolecules
Oleic Acid

Keywords

  • dilute aqeous solution
  • colloidal silica
  • spectrophotometric determination
  • acid polymerization
  • amorphous silica
  • biogenic silica
  • sodium-silicate
  • amino acids
  • neutral ph
  • degrees c

Cite this

Belton, David J. ; Deschaume, Olivier ; Patwardhan, Siddharth V. ; Perry, Carole C. / A solution study of silica sondensation and speciation with relevance to in vitro investigations of biosilicification. In: Journal of Physical Chemistry B. 2010 ; Vol. 114, No. 31. pp. 9947-9955.
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A solution study of silica sondensation and speciation with relevance to in vitro investigations of biosilicification. / Belton, David J.; Deschaume, Olivier; Patwardhan, Siddharth V.; Perry, Carole C.

In: Journal of Physical Chemistry B, Vol. 114, No. 31, 12.08.2010, p. 9947-9955.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A solution study of silica sondensation and speciation with relevance to in vitro investigations of biosilicification

AU - Belton, David J.

AU - Deschaume, Olivier

AU - Patwardhan, Siddharth V.

AU - Perry, Carole C.

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AB - Requiring mild synthesis conditions and possessing a high level of organization and functionality, biosilicas constitute a source of wonder and inspiration for both materials scientists and biologists. In order to understand how such biomaterials are formed and to apply this knowledge to the generation of novel bioinspired materials, a detailed study of the materials, as formed under biologically relevant conditions, is required. In this contribution, data from a detailed study of silica speciation and condensation using a model bioinspired silica precursor (silicon catechol complex, SCC) is presented The silicon complex quickly and controllably dissociates under neutral pH conditions to well-defined, metastable solutions of orthosilicic acid The formation of silicomolybdous (blue) complexes was used to monitor and study different stages of silicic acid condensation In parallel, the rates of silicomolybdic (yellow) complex formation, with mathematical modeling of the species present, was used to follow the solution speciation of polysilicic acids. The results obtained from the two assays correlate well. Monomeric Oleic acid, trimeric silicic acids, and different classes of oligomenc polysilicic acids and silica nuclei can be identified and their periods of stability during the early stages of silica condensation measured For experiments performed at a range of temperatures (273-323 K), an activation energy of 77 kJ.mol(-1) was obtained for the formation of trimers. The activation energies for the forward and reverse condensation reactions for addition of monomers to polysilicic acids (273-293 +/- 1 K) were 55.0 and 58.6 kJ.mol(-1), respectively. For temperatures above 293 K, these energies were reduced to 6 1 and 7.3 kJ.mol(-1), indicating a probable change in the prevailing condensation mechanism The impact of pH on the rates of condensation were measured There was a direct correlation between the apparent third-order rate constant for trimer formation and pH (4.7-6.9 +/- 0.1) while values for the reversible first-order rates reached a plateau at circumneutral pH. These different behaviors are discussed with reference to the generally accepted mechanism for silica condensation in which anionic silicate solution species are central to the condensation process. The results presented in this paper support the use of precursors such as silicon catecholate complexes in the study of biosilicification in vitro Further detailed experimentation is needed to increase our understanding of specific biomolecule silica interactions that ultimately generate the complex, finely detailed siliceous structures we observe in the world around us.

KW - dilute aqeous solution

KW - colloidal silica

KW - spectrophotometric determination

KW - acid polymerization

KW - amorphous silica

KW - biogenic silica

KW - sodium-silicate

KW - amino acids

KW - neutral ph

KW - degrees c

U2 - 10.1021/jp101347q

DO - 10.1021/jp101347q

M3 - Article

VL - 114

SP - 9947

EP - 9955

JO - Journal of Physical Chemistry B

T2 - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

IS - 31

ER -