Switch of Surface Adhesion to Cohesion by Dopa-Fe³⁺ Complexation, in Response to Microenvironment at the Mussel Plaque/Substrate Interface

Abstract

Although Dopa-Fe 3+ complexation is known to play an important role in mussel adhesion for providing mechanical properties, its function at the plaque/substrate interface, where actual surface adhesion occurs, remains unknown, with regard to interfacial mussel adhesive proteins (MAPs) type 3 fast variant (fp-3F) and type 5 (fp-5). Here, we confirmed Dopa-Fe 3+ complexation of interfacial MAPs and investigated the effects of Dopa-Fe 3+ complexation regarding both surface adhesion and cohesion. The force measurements using surface forces apparatus (SFA) analysis showed that intrinsic strong surface adhesion at low pH, which is similar to the local acidified environment present during the secretion of adhesive proteins, vanishes by Dopa-Fe 3+ complexation and alternatively, strong cohesion is generated in higher pH conditions similar to seawater. A high Dopa content increased the capacity for both surface adhesion and cohesion, but not at the same time. In contrast, a lack of Dopa resulted in both weak surface adhesion and cohesion without significant effects of Fe 3+ complexation. Our findings shed light on how mussels regulate Dopa functionality at the plaque/substrate interface, in response to the microenvironment, and might provide new insight for the design of mussel-inspired biomaterials.

A Self-Strengthening Epidermis-Like Smart Coating Enabled by Dynamic Iron Sequestration

“…The concomitant increase of scattering peaks for TA ( Figure 1c) is likely a result of the stabilization effect of phenolic ring by metal ion coordination and similar phenomena have been observed in previous studies. 27,28 In addition, XPS measurement can only detect the presence of iron in the ELSC after placing in saltwater (a 3.5 wt% NaCl solution) for 100 days, implying the minor amounts of iron (Supporting Information Figure S2). Fe 2p3/2 and Fe 2p1/2 signals are observed at around 711 and 725 eV, respectively, with a 2p peak separation of 14 eV, suggestive of the presence of Fe 3+ .…”

Paintable and Rapidly Bondable Conductive Hydrogels as Therapeutic Cardiac Patches

“…Therefore, the freshly formed hydrogel with uniformly distributed Ppy could be directly administered in vivo. Second, the Fe 3+ could form mono‐ or bis‐catechol‐Fe 3+ complexes with the dopamine groups in HPAE–Py polymer at neutral pH . The adhesion‐predominant catechol–Fe 3+ complexation could thus enhance the wet adhesion of the hydrogels.…”

Die chemischen Grundlagen der Adhäsion von Catechol

“…[140] Such works include AFM studies, [157] binding of DOPA-containing mfps [158] and hydrolysed peptides, [ 159 ] spectroscopic and chemical characterization of the complexes formed during cross-linking [160] and metal-mediated cross-linking in mfps. [161] In a recent study, Cha et al [162] confirmed DOPA-Fe(III) complexation in mfp-3F and mfp-5 and investigated its effect on both cohesion and surface adhesion (Figure 13). At low pH values (similar to those of the local acidic environments during the secretion of adhesive proteins), DOPA-Fe(III) complexation decreases.…”