The effect of pH and calcium ions on the stability of amphiphilic and anionic β-sheet peptide hydrogels

Authors

  • Shlomo Zarzhitsky,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
    2. Ilse Katz Institute for Nano-Science and Technology (IKI), Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Hodaya Edri,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Ziv Azoulay,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Ifat Cohen,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Yvonne Ventura,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Anna Gitelman,

    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • Hanna Rapaport

    Corresponding author
    1. Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
    2. Ilse Katz Institute for Nano-Science and Technology (IKI), Ben-Gurion University of the Negev, Beer-Sheva, Israel
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  • This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

ABSTRACT

Amphiphilic peptides can form bottom-up-designed self-assembled hydrogels composed of elongated fibril matrices that could find uses in various biologically-related systems, acting as platforms for drug delivery or scaffolds that mimic extracellular matrices in tissue regeneration systems. We have previously reported that the amphiphilic and anionic β-sheet forming peptide, Pro-Asp-(Phe-Asp)5-Pro, PFD-5, generates hydrogels that template calcium-phosphate mineral and as such, were able to enhance bone formation in vivo. Our earlier results prompted us to further exploit the effects of pH and calcium ion concentration on PFD-5 peptide in solution, in hydrogels and in mineral-loaded hydrogel compositions. Circular dichroism-based characterization of solutions of the peptide demonstrated transitions between the unfolded state to a β-sheet structure as function of peptide concentration, pH and calcium ion concentration. FTIR measurements were employed to monitor differences between the structure of the peptide in solution and in hydrogels. Rheology and dissolution studies demonstrated the improved stability of hydrogels prepared by a two-step procedure, where the peptides are dissolved and self-assemble in the first step, while in the second step, calcium ions are allowed to adsorb onto the system. These results, highlighting the effects of a few central factors on the structure, assembly and stability of amphiphilic and anionic β-sheet peptide systems, will contribute to the further development of designed self-assembled peptide systems from solutions to hydrogels and hydrogel-loaded matrices, such as mineral putty compositions. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 760–772, 2013.

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