Silicification and biosilicification: part 2. Silicification at pH 7 in the presence of a cationically charged polymer in solution and immobilized on substrates

Siddharth Patwardhan, M F Durstock, Stephen J. Clarson

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

Abstract

Biosilicification is facilitated by proteins and occurs under modest conditions in an aqueous medium (pH 7 and ambient temperature). Silicification at neutral pH in vitro has been shown to occur in the presence of various cationically charged synthetic macromolecules in solution. Here, the synthesis of silica from an aqueous silica precursor in the presence of poly(allylamine hydrochloride) (PAH) and polyacrylic acid (PAA) both in solution and immobilized on substrates is investigated. The results show that the formation of ordered silica structures under these modest conditions was favored for the PAH and the PAH-PAA in solution but neither for PAA in solution nor when the polymers were immobilized as PAH-PAA bilayers on flat substrates. It is possible that the immobilization of the PAH by the electrostatically self-assembly (ESA) technique may allow it to retain its catalytic function, while not allowing it to fulfill its role as a template / structure directing agent. The silica structures were characterized using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). For the PAH system in solution silica spheres were seen and for PAH-PAA in solution hexagonal silica structures were observed in co-existence with silica spheres. The results presented herein may be helpful in elucidating biosilicification mechanism(s) and should lead to a better understanding of silicification.
Original languageEnglish
Title of host publicationSynthesis and properties of silicones and silicone-modified materials
EditorsS.J. Clarson, J.J. Fitzgerald, M.J. Owen, D. Smith, M.E. VanDyke
Place of PublicationWashington
PublisherAmerican Chemical Society
Pages366-374
Number of pages8
ISBN (Print)0841238049
DOIs
Publication statusPublished - 10 Mar 2003
EventSymposium on Synthesis and Properties of Silicones and Silicone-Modified Materials held at the 221st National Meeting of the American-Chemical-Society - San Diego, United States
Duration: 1 Apr 20015 Apr 2001

Publication series

NameACS Symposium series
PublisherAmerican Chemical Society
Volume838
ISSN (Print)0097-6156

Conference

ConferenceSymposium on Synthesis and Properties of Silicones and Silicone-Modified Materials held at the 221st National Meeting of the American-Chemical-Society
Country/TerritoryUnited States
CitySan Diego
Period1/04/015/04/01

Keywords

  • biosilicification
  • silicification
  • ambient temperature
  • pH7
  • neutral pH
  • poly(allylamine hydrochloride) (PAH)
  • polyacrylic acid (PAA)
  • electrostatically self-assembly (ESA) technique

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