Adhesion mechanisms of the mussel foot proteins mfp-1 and mfp-3

Abstract

Mussels adhere to a variety of surfaces by depositing a highly specific ensemble of 3,4-dihydroxyphenyl-L-alanine (DOPA) containing proteins. The adhesive properties of Mytilus edulis foot proteins mfp-1 and mfp-3 were directly measured at the nano-scale by using a surface forces apparatus (SFA). An adhesion energy of order W Ϸ3 ؋ 10 ؊4 J/m 2 was achieved when separating two smooth and chemically inert surfaces of mica (a common alumino-silicate clay mineral) bridged or ''glued'' by mfp-3. This energy corresponds to an approximate force per plaque of Ϸ100 gm, more than enough to hold a mussel in place if no peeling occurs. In contrast, no adhesion was detected between mica surfaces bridged by mfp-1. AFM imaging and SFA experiments showed that mfp-1 can adhere well to one mica surface, but is unable to then link to another (unless sheared), even after prolonged contact time or increased load (pressure). Although mechanistic explanations for the different behaviors are not yet possible, the results are consistent with the apparent function of the proteins, i.e., mfp-1 is disposed as a ''protective'' coating, and mfp-3 as the adhesive or ''glue'' that binds mussels to surfaces. The results suggest that the adhesion on mica is due to weak physical interactions rather than chemical bonding, and that the strong adhesion forces of plaques arise as a consequence of their geometry (e.g., their inability to be peeled off) rather than a high intrinsic surface or adhesion energy, W. bioadhesion ͉ Mytilus edulis

Fusion of nacre, mussel, and lotus leaf: bio-inspired graphene composite paper with multifunctional integration

“…1e). [13][14][15] DOPA demonstrates high affinity for chemically distinct substrates via covalent or noncovalent interactions. Dopamine contains both side chain functionalities of DOPA and lysine, which resembles mussel adhesive proteins (Fig.…”

Polymerizing Like Mussels Do: Toward Synthetic Mussel Foot Proteins and Resistant Glues

“…Moreover, the specialized mfp‐3 and mfp‐5 that constitute the adhesion interface of mussels, reached maximum adhesive energy values at pH 5.5 on silica of 2.99 and 2.44 mJ m −2 with a contact time of 60 min,23 respectively, which are still below the average work of adhesion attained by polyU 1 C after only 60 s of contact time. It has also to be noted that a complete loss of adhesive function was reported at pH 7–7.522 for several mfps, including mfp‐1, whereas the artificial mfp analogues are able to perform at pH 6.8.…”

“…A similar trend for coatings of polyU 1 C and polyU 2 C with respect to masses and thicknesses on alumina surfaces is evident for coatings on fluoropolymer substrates (Supporting Information, Figure S43). The latter are known to be highly challenging for coating, on which nonetheless marine mussels can effectively adhere well 22. Estimated areal mass densities of 31±3 mg m −2 and 18±1 mg m −2 (Voight model) give theoretical layer thicknesses of 26±2 nm and 15±1 nm for polyU 1 C and polyU 2 C , respectively.…”

Three intrinsically unstructured mussel adhesive proteins, mfp‐1, mfp‐2, and mfp‐3: Analysis by circular dichroism

“…Recruitment of the atomic force microscope, nanoindentation, and the surface force apparatus (SFA) has contributed much to understanding the physical and mechanical properties of mussel byssus and byssal proteins particularly the mfps. [5][6][7][8][9] However, structural studies at different length scales have been hampered by considerable challenges, including a menagerie of peculiar post-translational modifications, mfp sequence polymorphism, 2,10 the inability to crystallize any of the mfps, difficulty of purifying mg quantities, and the instability of mfps in solution. 11 This has lead to a variety of experimental approximations, which may or may not be biologically relevant.…”