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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The zebra mussel, Dreissena polymorpha, owes its notoriety as a biofouler to its adhesive skills and opportunism. Adhesion by the adult mussel to hard substrata is mediated by a nonliving extracorporeal structure called the byssus, which is superficially similar to the byssus of marine mussels in that it consists of a tight bundle of sclerotized threads tipped by adhesive plaques. Juvenile zebra mussels secrete a homologous structure on settlement, but they also employ an elongated belaying byssus while climbing that consists of an elastic, mucous filament anchored at irregular intervals by a byssal thread and plaque. This multiply anchored belaying line can be 20 to 30 times the mussel length. Histochemical tests show that the thread and plaque of both kinds of byssus contains a complex distribution of proteins that are subject to chemical processing after secretion. This processing may result from the formation of crosslinks following the catecholoxidase-catalyzed oxidation of peptidyl 3,4-dihydroxyphenylalanine during sclerotization.
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PMID:The byssus of the zebra mussel, Dreissena polymorpha. I: Morphology and in situ protein processing during maturation. 818 Jun 27

Mussel adhesive proteins (MAPs) have received increased attention as potential biomedical and environmental friendly adhesives. However, practical application of MAPs has been severely limited by uneconomical extraction and unsuccessful genetic production. Developing new adhesives requires access to large quantities of material and demonstrations of bulk mechanical properties. Previously, the authors designed fp-151, a fusion protein comprised of six MAP type 1 (fp-1) decapeptide repeats at each MAP type 5 (fp-5) terminus and successfully expressed it in Escherichia coli. This recombinant hybrid protein exhibited high-level expression, a simple purification and high biocompatibility as well as strong adhesive ability on a micro-scale. In the present work, investigations on the bulk adhesive properties of semi-purified ( approximately 90% purity) fusion fp-151 were performed in air. The unmodified recombinant fp-151, as expressed, contains tyrosine residues and showed significant shear-adhesive forces ( approximately 0.33 MPa). Adhesion strength increased ( approximately 0.45 MPa) after enzymatic oxidation of tyrosine residues to l-3,4-dihydroxyphenylalanine (DOPA) groups. Addition of cross-linkers such as iron(III), manganese(III) and periodate (IO(4)(-)) generally enhanced adhesion, although too much addition decreased adhesion. Among the three cross-linking reagents examined, the non-metallic oxidant periodate showed the highest shear-adhesive forces ( approximately 0.86 MPa). In addition, it was found that adhesive strengths could be increased by adding weights to the samples. The highest adhesion strength found was that of DOPA-containing fp-151 cross-linked with periodate and having weights applied to the samples ( approximately 1.06 MPa). Taken together, the first bulk-scale adhesive force measurements are presented for an expressed recombinant hybrid mussel adhesive protein.
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PMID:Bulk adhesive strength of recombinant hybrid mussel adhesive protein. 1898 69

We present a study on the effects of cross-linking on the adhesive properties of bio-inspired 3,4-dihydroxyphenylalanine (DOPA). DOPA has a unique catechol moiety found in adhesive proteins in marine organisms, such as mussels and polychaete, which results in strong adhesion in aquatic conditions. Incorporation of this functional group in synthetic polymers provides the basis for pressure-sensitive adhesives for use in a broad range of environments. A series of cross-linked DOPA-containing polymers were prepared by adding divinyl cross-linking agent ethylene glycol dimethacrylate (EGDMA) to monomer mixtures of dopamine methacrylamide (DMA) and 2-methoxyethyl acrylate (MEA). Samples were prepared using a solvent-free microwave-assisted polymerization reaction and compared to a similar series of cross-linked MEA materials. Cross-linking with EGDMA tunes the viscoelastic properties of the adhesive material and has the advantage of not reacting with the catechol group that is responsible for the excellent adhesive performance of this material. Adhesion strength was measured by uniaxial indentation tests, which indicated that 0.001 mol % of EGDMA-cross-linked copolymer showed the highest work of adhesion in dry conditions, but non-cross-linked DMA was the highest in wet conditions. The results suggest that there is an optimal cross-linking degree that displays the highest adhesion by balancing viscous and elastic behaviors of the polymer but this appears to depend on the conditions. This concentration of cross-linker is well below the theoretical percolation threshold, and we propose that subtle changes in polymer viscoelastic properties can result in significant improvements in adhesion of DOPA-based materials. The properties of lightly cross-linked poly(DMA-co-MEA) were investigated by measurement of the frequency dependence of the storage modulus (G') and loss modulus (G''). The frequency-dependence of G' and magnitude of G'' showed gradual decreases with the fraction of EGDMA. Loosely cross-linked DMA copolymers, containing 0% and 0.001 mol % of EGDMA-cross-linked copolymers, displayed rheological behavior appropriate for pressure-sensitive adhesives characterized by a higher G' at high frequencies and lower G' at low frequencies. Our results indicate that dimethacrylate cross-linking of DMA copolymers can be used to enhance the adhesive properties of this unique material.
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PMID:Enhanced adhesion of dopamine methacrylamide elastomers via viscoelasticity tuning. 2118 92