Diversified Material Designs in Biological Underwater Adhesives - Structural Interfaces and Attachments in Biology - page 182

Fig. 9.8 Peptide- and protein-based materials from biological underwater adhesives. ( a ) Salt
concentration-dependent peptide self-assembly designed from cp-20k. ( b ) Self-assembly has a
threshold level close to the salt concentration of seawater. ( c ) The cp-19k protein as a multi-surface
coupling tag. The polymer particles were quickly covered with the bacterial recombinant protein
of Mrcp19k fused with green fluorescent protein and emitted fluorescence (reproduced, with
permission, from [ 84 ])
function [ 53 , 57 ] might be useful as multi-anchoring or specific anchoring tags to
deposit functional proteins onto a solid material (Fig. 9.8 )[ 84 ]. The protein would
be ready to use immediately after the bio-process production fusing it with a foreign
functional protein without post-modification, which is usually required in materials
with DOPA. Such tools would be useful for depositing functional proteins onto any
surface by genetic design.
Needless to say, researchers have long been interested in learning from nature
how to develop an adhesive to be used in humid conditions and in water. In
one study, a DOPA-containing polydecapeptide mimic was synthesized from the
sequence of the byssal coating protein. The aqueous solution of the peptide mimics
was spread onto pieces of iron, combined with air, and placed for 3 days in 60%
relative humidity. Without the addition of tyrosinase or oxidant, a tensile strength
of 28 kg/cm 2 was obtained [ 68 ]. A co-polypeptide of Tyr and Lys with the addition
of tyrosinase showed limited success, with a tensile strength of 30 kg/cm 2 in the
same conditions [ 85 ]. Adhesive strength of a co-polypeptide of DOPA and Lys was
also measured on strips of porcine bone and skin [ 86 ]. The co-polypeptide with an