1 research outputs found
Self-Assembled Nanofibers for Strong Underwater Adhesion: The Trick of Barnacles
Developing
adhesives that can function underwater remains a major
challenge for bioengineering, yet many marine creatures, exemplified
as mussels and barnacles, have evolved their unique proteinaceous
adhesives for strong wet adhesion. The mechanisms underlying the strong
adhesion of these natural adhesive proteins provide rich information
for biomimetic efforts. Here, combining atomic force microscopy (AFM)
imaging and force spectroscopy, we examine the effects of pH on the
self-assembly and adhesive properties of cp19k, a key barnacle underwater
adhesive protein. For the first time, we confirm that the bacterial
recombinant <i>Balanus albicostatus</i> cp19k (rBalcp19k),
which contains no 3,4-dihydroxyphenylalanine (DOPA) or any other amino
acids with post-translational modifications, can self-assemble into
aggregated nanofibers at acidic pHs. Under moderately acidic conditions,
the adhesion strength of unassembled monomeric rBalcp19k on mica is
only slightly lower than that of a commercially available mussel adhesive
protein mixture, yet the adhesion ability of rBalcp19k monomers decreases
significantly at increased pH. In contrast, upon preassembly at acidic
and low-salinity conditions, rBalcp19k nanofibers keep stable in basic
and high-salinity seawater and display much stronger adhesion and
thus show resistance to its adverse impacts. Besides, we find that
the adhesion ability of Balcp19k is not impaired when it is combined
with an N-terminal Thioredoxin (Trx) tag, yet whether the self-assembly
property will be disrupted is not determined. Collectively, the self-assembly-enhanced
adhesion presents a previously unexplored mechanism for the strong
wet adhesion of barnacle cement proteins and may lead to the design
of barnacle-inspired adhesive materials