Data from: The microscopic network structure of mussel (Mytilus) adhesive plaques

Marine mussels of the genus Mytilus live in the hostile intertidal zone,
attached to rocks, bio-fouled surfaces and each other via collagen-rich
threads ending in adhesive pads, the plaques. Plaques adhere in salty,
alkaline seawater, withstanding waves and tidal currents. Each plaque
requires a force of several newtons to detach. Although the molecular
composition of the plaques has been well studied, a complete understanding
of supra-molecular plaque architecture and its role in maintaining
adhesive strength remains elusive. Here, electron microscopy and neutron
scattering studies of plaques harvested from Mytilus californianus and
Mytilus galloprovincialis reveal a complex network structure reminiscent
of structural foams. Two characteristic length scales are observed
characterizing a dense meshwork (approx. 100 nm) with large
interpenetrating pores (approx. 1 µm). The network withstands chemical
denaturation, indicating significant cross-linking. Plaques formed at
lower temperatures have finer network struts, from which we hypothesize a
kinetically controlled formation mechanism. When mussels are induced to
create plaques, the resulting structure lacks a well-defined network
architecture, showcasing the importance of processing over self-assembly.
Together, these new data provide essential insight into plaque structure
and formation and set the foundation to understand the role of plaque
structure in stress distribution and toughening in natural and biomimetic
materials.