Amyloid-Based Natural Adhesives and Cements - The Functional Fold: Amyloid Structures in Nature - page 137

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similar characteristics to an amyloid plaque by Kamino but

not confirmed as being amylogenic until a broad range of analytical
tools were later employed.

et al .,

Using energy dispersive X-ray analysis
and FTIR spectroscopy, in addition to the chemical staining and
AFM, Sullan

21,22

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et al . revealed amyloid in cement from the barnacle

Balanus and described

that the amyloid component provided toughness to the cement.
Barlow

amphitrite ( Amphibalanus amphitrite ),

used similar analytical techniques, and included CD
spectroscopy, to characterize the primary and secondary cement of
the same barnacle species, finding both cements to be composed
largely of amyloid fibres along with an unidentified globular protein
component .
These recent reports of amyloid-based adhesives and cements
indicate that they are likely to be widespread in nature, in different
environments, and produced by phylogenetically different organisms.

et al .

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8.3 AFM as a Tool for Exploring

Natural Adhesives

One approach to investigating the structure-function relationships
of individual biomolecules of natural adhesives is to use a local
force probe, known as AFM.

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AFM measures intermolecular
forces between a sharp tip located at the end of a cantilever, and
the sample surface of interest, and builds up a three-dimensional
image corresponding to the surface topography. The capabilities of
AFM instrumentation facilitate molecular resolution imaging under
physiological conditions with minimal to no sample preparation.

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In other words, single adhesive polymers may be imaged in situ ,

without any fixation or subsequent processing.
This ability of AFM to directly probe small volumes of biological
material with nanoscale precision, in an ambient environment,
makes it ideally suited to exploring natural adhesives and cements.
Through single molecule force spectroscopy, AFM also allows
nanoscale characterization of the mechanical properties of biological
materials such as their adhesive strength and elasticity. For many

biological molecules, response to an externally applied force is
important functionally and structurally and thus force spectroscopy
has become a valuable analytical tool for the investigation of physical
and mechanical properties of single biomolecules in aqueous
environments.

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