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CHARACTERIZATION OF THE ADHESIVE MUCILAGES SECRETED BY LIVE DIATOM CELLS USING ATOMIC FORCE MICROSCOPY
Publication year - 2001
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2001.jpy37303-59.x
Subject(s) - mucilage , force spectroscopy , adhesive , adhesion , diatom , atomic force microscopy , cantilever , cell wall , biophysics , materials science , contact angle , biology , composite material , nanotechnology , layer (electronics) , botany
Higgins, M. J., Mulvaney, P. & Wetherbee, R. Schools of Botany and Chemistry, University of Melbourne, Victoria 3052, Australia Atomic Force Microscopy (AFM) resolved the topography and mechanical properties of the adhesive mucilages secreted by living cells of the fouling diatom Craspedostauros australis. Tapping mode images of live cells revealed a soft, cohesive mucilage layer that encased most of the diatom silica cell wall. Force curves revealed that this type of mucilage had an adhesion strength of 71.2 mN m‐1 and a compressibility of 5.7 x 106 N m‐2. High force contact mode imaging (i.e., increased set‐point voltage) resulted in the ‘raking’ of the cohesive mucilage to reveal the underlying, silicified wall structures. Further imaging of cantilever ‘cleaned’ cell walls of live cells in stationary growth phase revealed the active secretion of soft mucilage via pore openings in the girdle bands. A second adhesive mucilage in the form of distinct strands was found to project through the silica valve walls at the raphes, and to be involved in cell adhesion and motility. Single force spectroscopy measurements revealed that an adhesive strand (or strands) was resistant to breaking forces greater than 40 nN and could only be detached from the AFM cantilever probe using mechanical retraction of the piezo. Using the Worm‐like Chain model (WLC) the chain length and persistence length of the strands were calculated to be 3μm and 0.04Å, respectively. These values imply that the strands are very adhesive and strong compared to other single biological polymers, and could account for the complex interactions between diatom cells and their substratum.