Prospective energy densities in the forisome, a new smart material

William F. Pickard, Michael Knoblauch, Winfried S. Peters, Amy Q. Shen

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The forisome is a protein structure of plants which, in low Ca 2+ solutions, assumes a crystalline condensed conformation and, at high Ca2+, swells to a dispersed conformation; this transition has been attributed to electrostatic deformation of protein "modules". Forisomes could become an important smart material if the energy density of transformation approached 1 MJ m- 3. Quantitation of the forisome as a charged porous continuum permeated by electrolyte fails by orders of magnitude to achieve this energy density electrostatically. However, condensed → dispersed transitions can be visualized alternatively: (i) an ionic bond near the surface of a forisome crystal dissolves to produce two bound surface charges; (ii) the anionic site bonds to Ca2+ becoming less negative; (iii) the two sites repel each other and move apart drawing in water; (iv) electrolyte anions are attracted, bringing with them bound water; (v) this transition propagates throughout the crystal, with incompressible imbibed electrolyte stabilizing the initial separation. With the above transition sequence, it seems possible to achieve an energy density of 0.5 MJ m- 3 if the "modules" in the crystal are roughly 10 nm on a side.

Original languageEnglish (US)
Pages (from-to)104-112
Number of pages9
JournalMaterials Science and Engineering C
Issue number1
StatePublished - Jan 2006


  • Bond valence model
  • Energy density
  • Forisome
  • P-protein
  • Phloem
  • Smart materials

ASJC Scopus subject areas

  • Medicine(all)


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