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1.
Langmuir ; 30(38): 11375-85, 2014 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-25181015

RESUMO

This photophysical study characterizes the generality of intermolecular electronic interactions present within nanomaterials derived from self-assembling oligopeptides with embedded π-conjugated oligophenylenevinylene (OPV) subunits stilbene and distyrylbenzene that in principle present two distinct ß-sheet motifs. Two different synthetic approaches led to oligopeptides that upon self-assembly are expected to self-assemble into multimeric aggregates stabilized by ß-sheet-like secondary structures. The target molecules express either two C-termini linked to the central OPV core (symmetric peptides) or the more common N-termini to C-termini polarity typical of natural oligopeptides (nonsymmetric peptides). Both peptide secondary structures were shown to form extended 1-D peptide aggregates with intimate intermolecular π-electron interactions. Differences in length of the π-conjugated OPV segments resulted in differing extents of intermolecular interactions and the resulting photophysics. The peptides containing the shorter stilbene (OPV2) units showed little ground state interactions and resulted in excimeric emission, while the longer distyrylbenzene (OPV3) peptides had different ground state interactions between adjacent π-conjugated subunits resulting in either perturbed electronic properties arising from exciton coupling or excimer-like excited states. Molecular dynamics simulations of nascent aggregate formation predict peptide dimerization to be a spontaneous process, possessing thermodynamic driving potentials in the range 2-6 kcal/mol for the four molecules considered. Antiparallel stacking of the peptides containing an OPV3 subunit is thermodynamically favored over the parallel orientation, whereas both arrangements are equally favored for the peptides containing an OPV2 subunit. This study validates the generality of peptide-π-peptide self-assembly to provide electronically delocalized supramolecular structures and suggests flexibility in peptide sequence design as a way to tune the material properties of π-conjugated supramolecular polymers.


Assuntos
Nanoestruturas/química , Oligopeptídeos/química , Elétrons , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Estrutura Molecular , Estilbenos/química , Estirenos/química
2.
Langmuir ; 30(20): 5946-56, 2014 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-24802289

RESUMO

We present a systematic study of the photophysical properties of one-dimensional electronically delocalized nanostructures assembled from π-conjugated subunits embedded within oligopeptide backbones. The nature of the excited states within these nanostructures is studied as a function of primary amino acid sequence utilizing steady-state and time-resolved spectroscopies, and their atomistic structure is probed by molecular simulation. Variations introduced into the amino acid side chains at specific residue locations along the molecular peptide backbone lead to pronounced changes in the observed photophysical behavior of the fibrillar structures (spanning H-like excitonic coupling and disordered excimeric coupling) that arise from subtle changes in the π-stacking within them. These results indicate that residue modification-in terms of relative size, solvation properties, and with respect to the distance from the central π-electron core-enables the ability to tune chromophore packing and the resulting photophysics of supramolecular assemblies of π-conjugated bioelectronic materials in a rational and systematic manner.


Assuntos
Nanoestruturas/química , Peptídeos/química , Sequência de Aminoácidos
3.
Macromol Biosci ; 17(10)2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28248002

RESUMO

Antimicrobial properties of a long-chain, synthetic, cationic, and hydrophobic amino acid block copolymer are reported. In 5 and 60 min time-kill assays, solutions of K100 L40 block copolymers (poly(l-lysine·hydrochloride)100 -b-poly(l-leucine)40 ) at concentrations of 10-100 µg mL-1 show multi-log reductions in colony forming units of Gram-positive and Gram-negative bacteria, as well as yeast, including multidrug-resistant strains. Driven by association of hydrophobic segments, K100 L40 copolymers form viscous solutions and self-supporting hydrogels in water at concentrations of 1 and 2 wt%, respectively. These K100 L40 preparations provide an effective barrier to microbial contamination of wounds, as measured by multi-log decreases of tissue-associated bacteria with deliberate inoculation of porcine skin explants, porcine open wounds, and rodent closed wounds with foreign body. Based on these findings, amino acid copolymers with the features of K100 L40 can combine potent, direct antimicrobial activity and barrier properties in one biopolymer for a new approach to prevention of wound infections.


Assuntos
Anti-Infecciosos/farmacologia , Curativos Hidrocoloides , Hidrogéis/farmacologia , Peptídeos/farmacologia , Polilisina/farmacologia , Ferida Cirúrgica/tratamento farmacológico , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/crescimento & desenvolvimento , Animais , Anti-Infecciosos/síntese química , Candida albicans/efeitos dos fármacos , Candida albicans/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Feminino , Fusobacterium/efeitos dos fármacos , Fusobacterium/crescimento & desenvolvimento , Hidrogéis/síntese química , Interações Hidrofóbicas e Hidrofílicas , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Peptídeos/química , Polilisina/química , Polimerização , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pele/efeitos dos fármacos , Pele/microbiologia , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/crescimento & desenvolvimento , Ferida Cirúrgica/microbiologia , Suínos , Técnicas de Cultura de Tecidos
4.
Adv Mater ; 25(44): 6398-404, 2013 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-23966206

RESUMO

A microfluidic-based directed assembly strategy is employed to form highly aligned supramolecular structures. Formation of aligned synthetic oligopeptide nanostructures is accomplished using planar extensional flow, which induces alignment of underlying material suprastructures. Fluidic-directed assembly of supramolecular structures allows for unprecedented manipulation at the nano- and mesoscales, which has the potential to provide rapid and efficient control of functional material properties.

5.
Chem Commun (Camb) ; 46(22): 3947-9, 2010 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-20431818

RESUMO

We report a convenient method to incorporate pi-electron units into peptides that assemble into amyloid-like supramolecular polymers, discussing the scope of the process and preliminary characterization of the resulting nanomaterials. Self-assembly manipulates these "electronic peptides" into delocalized sub-10 nm 1-D nanostructures under completely aqueous conditions.


Assuntos
Peptídeos/química , Dimerização , Elétrons , Concentração de Íons de Hidrogênio , Proteínas Imobilizadas/química , Nanoestruturas/química , Estrutura Secundária de Proteína , Água/química
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