Surface mechanical properties of the spore adhesive of the green alga Ulva

GC Walker, Y Sun, S Guo, John Finlay, Maureen Callow, James Callow

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The mechanical properties of the adhesive produced by spores of the green, marine, fouling alga Ulva linza are reported. Atomic force microscopy studies were performed and nanoindentation data were analyzed using a model for an asymmetric indenter. Freshly secreted adhesive is characterized by multiple layers. We found that the modulus of the outer similar to 600-nm thick layer was about 0.2 +/- 0.1 MPa, whereas the modulus of the inner layer was about 3 +/- 1 MPa. Older adhesive showed the formation of a "crust" of harder material with a yield strength of similar to 20 MPa at a loading rate of 2.5 x 10(-6) N.s(-1). Mechanical properties under tension are also described, and extension profiles that showed either constant or nonlinear force changes with tip-sample separation were observed. Models for both kinds of behavior are described. The work of adhesion between poly-dimethylsiloxone (PDMS)-coated AFM tips and the adhesive was determined to be less than 1.5 mJ.m(-2).
Original languageEnglish
Pages (from-to)1101-1118
Number of pages18
JournalThe Journal of Adhesion
Volume81
Issue number10-11
DOIs
Publication statusPublished - 1 Oct 2005

Keywords

  • bioadhesive
  • atomic force microscope
  • PDMS
  • marine alga
  • Ulva

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