88 research outputs found
Accessing the Next Generation of Synthetic MusselâGlue Polymers via MusselâInspired Polymerization
The formation of cysteinyldopa as biogenic connectivity in proteins is used to inspire a chemical pathway toward mussel-adhesive mimics. The mussel-inspired polymerization (MIPoly) exploits the chemically diverse family of bisphenol monomers that is oxidizable with 2-iodoxybenzoic acid to give bisquinones. Those react at room temperature with dithiols in Michael-type polyadditions, which leads to polymers with thiolâcatechol connectivities (TCC). A set of TCC polymers proved adhesive behavior even on challenging poly(propylene) substrates, where they compete with commercial epoxy resins in dry adhesive strength. MIPoly promises facile scale up and exhibits high modularity to tailor adhesives, as proven on a small library where one candidate showed wet adhesion on aluminum substrates in both water and sea water models.Verband der Chemischen Industrie
http://dx.doi.org/10.13039/100007215Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659Peer Reviewe
Peptide-Assisted Design of Precision Polymer Sequences
Functional sequences of monodisperse, sequenceâdefined oligo(amideâurethane)s are designed based on a peptide sequence as blueprint. The translation of a discrete sideâchain functionality sequence from a known peptideâbased solubilizer of the photosensitizer metaâtetra(hydroxyphenyl)âchlorin, into a nonâpeptidic precision polymer backbone is demonstrated. The resulting peptidomimetic precision polymers retain the functions of the parent peptide sequence, showing analogues sensitivity toward single monomer mutations/exchanges and even exceeding the parent peptide equivalent by reaching up to 69% higher payload capacities and more favored release kinetics.Peer Reviewe
Antimicrobial Finish of Polyethersulfone Membranes: Sticking PhotosensitizersâLike Marine Mussels Would Do
Biofouling is one of the most serious problems in membrane filtration systems for water treatment. An easily applicable antimicrobial finish of polyethersulfone (PES) filter membranes is shown by derivatizing an approved chlorin photosensitizer drug with adhesive ortho-catechol functionalities as known from l-3,4-dihydroxyphenylalanin (Dopa) residues of marine mussel glues. The chemical structure of the second-generation photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)chlorin (m-THPC) is modified by 2-iodoxybenzoic acid (IBX) oxidation, transforming the peripheric meta-phenols of m-THPC into ortho-catechols, and thus improving the adsorption properties of m-THPC derivatives onto PES material. Stable coatings are formed that preserve chlorin's capability to generate singlet oxygen under visible light illumination. The modification of one or two phenol groups out of the four m-THPC substituents leads to an optimum in the generation of active singlet oxygen, and thus the finish significantly reduces the bacterial growth of gram-negative Escherichia coli and gram-positive Micrococcus luteus on the PES membranes.Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659Peer Reviewe
Implementing Zn2+ ion and pH-value control into artificial mussel glue proteins by abstracting a His-rich domain from preCollagen
A His-rich domain of preCollagen-D found in byssal threads is derivatized with Cys and Dopa flanks to allow for mussel-inspired polymerization. Artificial mussel glue proteins are accessed that combine cysteinyldopa for adhesion with sequences for pH or Zn2+ induced ÎČ-sheet formation. The artificial constructs show strong adsorption to Al2O3, the resulting coatings tolerate hypersaline conditions and cohesion is improved by activating the ÎČ-sheet formation, that enhances E-modulus up to 60%.Peer Reviewe
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Polymerizing Like Mussels Do: Toward Synthetic Mussel Foot Proteins and Resistant Glues
A novel strategy to generate adhesive protein analogues by enzyme-induced polymerization of peptides is reported. Peptide polymerization relies on tyrosinase oxidation of tyrosine residues to Dopaquinones, which rapidly form cysteinyldopa-moieties with free thiols from cysteine residues, thereby linking unimers and generating adhesive polymers. The resulting artificial protein analogues show strong adsorption to different surfaces, even resisting hypersaline conditions. Remarkable adhesion energies of up to 10.9â
mJâmâ2 are found in single adhesion events and average values are superior to those reported for mussel foot proteins that constitute the gluing interfaces
The nucleus ^198 Au investigated with neutron capture and transfer reactions. II. Construction of the level scheme and calculation of level densities
The level scheme of ^198 Au was constructed. Up to 1560 keV a total of 111 (d,p) and 125 (n,gamma) levels was included, frequently with spin and parity assignments. The results for level densities are calculated in interacting boson-fermion-fermion model (IBFFM) and Gaussian polynomial method (GPM) and are compared to the present data
The nucleus ^198 Au investigated with neutron capture and transfer reactions I. Experiments and evaluation
The transfer reaction ^197 Au(d,p)^198 Au was measured at the Tandem Accelerator in Munich. The ^197 Au(n,gamma)^198 Au and ^197 Au(n,e)^198 Au reactions were performed at the High Flux Reactor of ILL, Grenoble. Up to 1560 keV a total of 111 levels were observed by the (d,p) reaction and 125 by the (n,gamma) reaction. For many of the levels, spins and parities were assigned. Additional information was obtained from summed (n,gamma gamma) coincidences measured in Dubna
ProuÄavanje jezgre 198au pomoÄu neutronskog uhvata i (d,p) reakcijom. I. Eksperimenti i procjena
The transfer reaction 197Au(d,p)198Au was measured at the Tandem Accelerator in Munich. The 197Au(n,Îł) 198Au and 197Au(n,e)198Au reactions were performed at the High Flux Reactor of ILL, Grenoble. Up to 1560 keV a total of 111 levels were observed by the (d,p) reaction and 125 by the (n,Îł) reaction. For many of the levels, spins and parities were assigned. Additional information was obtained from summed (n,γγ) coincidences measured in Dubna.NaÄinjena su mjerenja relacije 197Au(d,p)198Au pomoÄu tandem Van de Graaff akceleratora u Munchenu, a reakcije 197Au(n,Îł) 198Au i 197Au(n,e)198Au prouÄavane su pri nuklearnom reaktoru u Institutu LaneâLaugevin u Grenoblu. Reakcijom (d,p) opaĆŸeno je do energije uzbude od 156 keV ukupno 111 nivoa, a reakcijom (n,Îł) 125 nivoa. Za mnoge nivoe utvrÄeni su momenti impulsa i parnosti. Dodatni su podaci postignuti mjerenjem zbrojnih (n,γγ) sudara u Institutu u Dubni
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