Purification of an iron-binding peptide from scad (Decapterus maruadsi) processing by-products and its effects on iron absorption by Caco-2 cells.

This work was aimed at producing peptides containing iron-binding capabilities from scad (Decapterus maruadsi) processing by-product with alcalase hydrolysis. The chelating peptides were purified by ultrafiltration, immobilized-metal affinity chromatography, gel filtration chromatography, and reversed-phase high-performance liquid chromatography. A novel iron-binding peptide was purified with 1,386.

Plantaricin NC8 from Lactobacillus plantarum causes cell membrane disruption to Micrococcus luteus without targeting lipid II.

Plantaricin NC8, a two-peptide non-lantibiotic class IIb bacteriocin composed of PLNC8α and PLNC8β and derived from Lactobacillus plantarum ZJ316, has been shown to be highly potent against a range of bacteria and fungi. In this study, we assessed the antimicrobial mechanism of plantaricin NC8 against the most sensitive bacterial strain, Micrococcus luteus CGMCC 1.193.

Strategies for screening, purification and characterization of bacteriocins.

Bacteriocins are bioactive antimicrobial peptides synthesized in the ribosome of numerous bacteria and released extracellularly. Bacteriocins have the ability to kill or inhibit the growth of prokaryotes and could potentially be useful against pathogens and antibiotic-resistant strains of bacteria. The antimicrobial mechanisms and relatively narrow killing spectrums of bacteriocins distinguish them from traditional broad-spectrum antibiotics, making them possible candidates to replace antibiotics in the future.

Purification, Characterization, and Mode of Action of Pentocin JL-1, a Novel Bacteriocin Isolated from , against Drug-Resistant .

and its drug-resistant strains, which threaten public health and food safety, are in need of effective control by biopreservatives. A novel bacteriocin, pentocin JL-1, produced by that was isolated from the intestinal tract of , was purified by a four-step chromatographic process. Mass spectrometry based on MALDI-TOF indicated that pentocin JL-1 has a molecular mass of 2987.

Two-Dimensional Controlled Syntheses of Polypeptide Molecular Brushes via -Carboxyanhydride Ring-Opening Polymerization and Ring-Opening Metathesis Polymerization.

Well-defined molecular brushes bearing polypeptides as side chains were prepared by a "grafting through" synthetic strategy with two-dimensional control over the brush molecular architectures. By integrating -carboxyanhydride ring-opening polymerizations (NCA ROPs) and ring-opening metathesis polymerizations (ROMPs), desirable segment lengths of polypeptide side chains and polynorbornene brush backbones were independently constructed in controlled manners. The N flow accelerated NCA ROP was utilized to prepare polypeptide macromonomers with different lengths initiated from a norbornene-based primary amine, and those macromonomers were then polymerized via ROMP.

Multi-responsive polypeptide hydrogels derived from N-carboxyanhydride terpolymerizations for delivery of nonsteroidal anti-inflammatory drugs.

A polypeptide-based hydrogel system, when prepared from a diblock polymer with a ternary copolypeptide as one block, exhibited thermo-, mechano- and enzyme-responsive properties, which enabled the encapsulation of naproxen (Npx) during the sol-gel transition and its release in the gel state. Statistical terpolymerizations of l-alanine (Ala), glycine (Gly) and l-isoleucine (Ile) NCAs at a 1 : 1 : 1 feed ratio initiated by monomethoxy monoamino-terminated poly(ethylene glycol) afforded a series of methoxy poly(ethylene glycol)-block-poly(l-alanine-co-glycine-co-l-isoleucine) (mPEG-b-P(A-G-I)) block polymers. β-Sheets were the dominant secondary structures within the polypeptide segments, which facilitated a heat-induced sol-to-gel transition, resulting from the supramolecular assembly of β-sheets into nanofibrils.

Reversible photo-patterning of soft conductive materials via spatially-defined supramolecular assembly.

A strategy for reversible patterning of soft conductive materials is described, based upon a combination of peptide-based block copolymer hydrogelators and photo-thermally-active carbon nanotubes. This composite displays photo-responsive gelation at application-relevant timescales (<10 s), allowing for rapid and spatially-defined construction of conductive patterns (>100 S m(-1)), which, additionally, hold the capability to revert to sol upon sonication for reprocessing.

Well-defined diblock brush polymer-drug conjugates for sustained delivery of paclitaxel.

Using the 3(rd) generation Grubbs' catalyst as the initiator, diblock brush polymer drug conjugates (BPDCs) were synthesized by sequential ring-opening metathesis polymerization (ROMP) of a hydrophilic poly(ethylene glycol) (PEG)-based norbornene (NB)-functionalized macromonomer and a hydrophobic paclitaxel (PTXL)-based NB-functionalized monomer. These amphiphilic diblock BPDCs had well-defined structures, with narrow molecular weight distributions (Mw/Mn = 1.10-1.

Facile Synthesis of a Phosphorylcholine-Based Zwitterionic Amphiphilic Copolymer for Anti-Biofouling Coatings.

An antibiofouling polymer coating, combined with both zwitterionic and amphiphilic features, is engineered by a two-step modification of a commodity polymer. The surface properties of the resultant polymer coating can be easily tuned by varying the extent of cross-linking in the network. Higher antibiofouling efficiency was observed for these surfaces vs.

Improving paclitaxel delivery: in vitro and in vivo characterization of PEGylated polyphosphoester-based nanocarriers.

Nanomaterials have great potential to offer effective treatment against devastating diseases by providing sustained release of high concentrations of therapeutic agents locally, especially when the route of administration allows for direct access to the diseased tissues. Biodegradable polyphosphoester-based polymeric micelles and shell cross-linked knedel-like nanoparticles (SCKs) have been designed from amphiphilic block-graft terpolymers, PEBP-b-PBYP-g-PEG, which effectively incorporate high concentrations of paclitaxel (PTX). Well-dispersed nanoparticles physically loaded with PTX were prepared, exhibiting desirable physiochemical characteristics.

Multi-responsive Hydrogels Derived from the Self-assembly of Tethered Allyl-functionalized Racemic Oligopeptides.

A multi-responsive triblock hydrogelator oligo(dl-allylglycine)--poly(ethylene glycol)-oligo(dl-allylglycine) (ODLAG--PEG--ODLAG) was synthesized facilely by ring-opening polymerization (ROP) of DLAG -carboxyanhydride (NCA) with a diamino-terminated PEG as the macroinitiator. This system exhibited heat-induced sol-to-gel transitions and either sonication- or enzyme-induced gel-to-sol transitions. The -sheeting of the oligopeptide segments was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and wide-angle X-ray scattering (WAXS).

Construction of a versatile and functional nanoparticle platform derived from a helical diblock copolypeptide-based biomimetic polymer.

Sequential polymerization of -carboxyanhydrides accelerated by nitrogen flow is utilized to generate a novel well-defined diblock copolypeptide (PDI = 1.08), with incorporation of alkyne-functionalized side-chain groups allowing for rapid and efficient thiol-yne click-type modifications, followed by self-assembly into nanopure water to construct a helical polypeptide-based versatile and functional nanoparticle platform.

Supramolecularly knitted tethered oligopeptide/single-walled carbon nanotube organogels.

A facile polymerization of an allyl-functionalized N-carboxyanhydride (NCA) monomer is utilized to construct an A-B-A-type triblock structure containing β-sheet-rich oligomeric peptide segments tethered by a poly(ethylene oxide) chain, which are capable of dispersing and gelating single-walled carbon nanotubes (SWCNTs) noncovalently in organic solvents, resulting in significant enhancement of the mechanical properties of polypeptide-based organogels.

Tunable mechano-responsive organogels by ring-opening copolymerizations of -carboxyanhydrides.

The simple copolymerization of -carboxyanhydride (NCA) monomers is utilized to generate copolypeptides having a combination of α-helix and β-sheet sub-structures that, when grown from a solvophilic synthetic polymer block segment, are capable of driving mechano-responsive supramolecular sol-to-gel-to-sol and sol-to-gel-to-gel transitions reversibly, which allow also for injection-based processing and self-healing behaviors. A new type of polypeptide-based organogelator, methoxy poly(ethylene glycol)--poly(γ-benzyl-l-glutamate--glycine) (mPEG--P(BLG--Gly)), is facilely synthesized by statistical ring-opening copolymerizations (ROPs) of γ-benzyl-l-glutamate (BLG) and glycine (Gly) NCAs initiated by mPEG-amine. These systems exhibit tunable secondary structures and result in sonication stimulus responsiveness of the organogels with the polypeptide segment variation, controlled by varying the ratio of BLG NCA to Gly NCA during the copolymerizations.

Programmed hydrolysis of nanoassemblies by electrostatic interaction-mediated enzymatic-degradation.

Electrostatic interaction-mediated enzymatic-hydrolysis of poly(lactide)-containing nanoscale assemblies is described. At physiological pH, degradable core-shell morphologies with charged shells can readily attract or repel enzymes carrying opposite or similar charges, respectively.

Polyphosphoester-based cationic nanoparticles serendipitously release integral biologically-active components to serve as novel degradable inducible nitric oxide synthase inhibitors.

A degradable polyphosphoester (PPE)-based cationic nanoparticle (cSCK), which is integrated constructed as a novel degradable drug device, demonstrates surprisingly efficient inhibition of inducible nitric oxide synthase (iNOS) transcription, and eventually inhibits nitric oxide (NO) over-production, without loading of any specific therapeutic drugs. This system may serve as a promising anti-inflammatory agent toward the treatment of acute lung injury.

A Simple and Efficient Synthesis of an Acid-labile Polyphosphoramidate by Organobase-catalyzed Ring-Opening Polymerization and Transformation to Polyphosphoester Ionomers by Acid Treatment.

The direct synthesis of an acid-labile polyphosphoramidate by organobase-catalyzed ring-opening polymerization and an overall two-step preparation of polyphosphodiester ionomers (PPEI) by acid-assisted cleavage of the phosphoramidate bonds along the backbone of the polyphosphoramidate were developed in this study. The ultrafast organobase-catalyzed ring-opening polymerization of a cyclic phospholane methoxyethyl amidate monomer initiated by benzyl alcohol allowed for the preparation of well-defined polyphosphoramidates (PPA) with predictable molecular weights, narrow molecular weight distributions (PDI<1.10), and well-defined chain ends.

Poly(ethylene oxide)-block-polyphosphoester-graft-paclitaxel conjugates with acid-labile linkages as a pH-sensitive and functional nanoscopic platform for paclitaxel delivery.

There has been an increasing interest to develop new types of stimuli-responsive drug delivery vehicles with high drug loading and controlled release properties for chemotherapeutics. An acid-labile poly(ethylene oxide)-block-polyphosphoester-graft-PTX drug conjugate (PEO-b-PPE-g-PTX G2) degradable, polymeric paclitaxel (PTX) conjugate containing ultra-high levels of PTX loading is improved significantly, in this second-generation development, which involves connection of each PTX molecule to the polymer backbone via a pH-sensitive β-thiopropionate linkage. The PEO-b-PPE-g-PTX G2 forms well-defined nanoparticles in an aqueous solution, by direct dissolution into water, with a number-averaged hydrodynamic diameter of 114 ± 31 nm, and exhibits a PTX loading capacity as high as 53 wt%, with a maximum PTX concentration of 0.

Responsive organogels formed by supramolecular self assembly of PEG--allyl-functionalized racemic polypeptides into β-sheet-driven polymeric ribbons.

A chemically reactive hybrid diblock polypeptide gelator poly(ethylene glycol)--poly(dl-allylglycine) (PEG--PDLAG) is an exceptional material, due to the characteristics of thermo-reversible organogel formation driven by the combination of a hydrophilic polymer chain linked to a racemic oligomeric homopeptide segment in a range of organic solvents. One-dimensional stacking of the block copolymers is demonstrated by ATR-FTIR spectroscopy, wide-angle X-ray scattering to be driven by the supramolecular assembly of β-sheets in peptide blocks to afford well-defined fiber-like structures, resulting in gelation. These supramolecular interactions are sufficiently strong to achieve ultra low critical gelation concentrations (.

A facile glovebox-free strategy to significantly accelerate the syntheses of well-defined polypeptides by -carboxyanhydride (NCA) ring opening polymerizations.

A facile N flow-accelerated -carboxyanhydride ring opening polymerization (NCA ROP) is demonstrated, herein, with rigorous kinetic studies to evaluate the methodology in detail. By using -hexylamine as initiator and γ-benzyl-L-glutamate -carboxyanhydride (BLG-NCA) as monomer, the NCA ROP a normal amine mechanism (NAM) reached 90% conversion in 2 h under N flow at room temperature in a fume hood, much shorter than the time required for the same polymerization conducted in a glove box (14 h). The efficient removal of CO from the reaction by N flow drove the carbamic acid-amine equilibrium toward the formation of active nucleophilic amino termini and promoted polymerization.

Quasi-phase-matched second-harmonic Talbot self-imaging in a 2D periodically-poled LiTaO3 crystal.

We demonstrate the improved second-harmonic Talbot self-imaging through the quasi-phase-matching technique in a 2D periodically-poled LiTaO(3) crystal. The domain structure not only composes a nonlinear optical grating which is necessary to realize nonlinear Talbot self-imaging, but also provides reciprocal vectors to satisfy the phase-matching condition for second-harmonic generation. Our experimental results show that quasi-phase-matching can improve the intensity of the second-harmonic Talbot self-imaging by a factor of 21.

Shell crosslinked knedel-like nanoparticles for delivery of cisplatin: effects of crosslinking.

Polymeric micelles and shell crosslinked knedel-like (SCK) nanoparticles were loaded with up to 48% (w/w) cisplatin. These spherical cisplatin-loaded nanoparticles displayed sustained platinum release over 5 days in PBS, enhanced stability over free cisplatin in aqueous milieu, and significant antitumor activity in vitro against two cancer cell lines.

Poly(ethylene oxide)--polyphosphester-based Paclitaxel Conjugates as a Platform for Ultra-high Paclitaxel-loaded Multifunctional Nanoparticles.

A new type of degradable, nanoscopic polymer assembly containing ultra-high levels of drug loading covalent attachment within amphiphilic core-shell nanoparticle morphology has been generated as a potentially effective and safe anti-cancer agent. Poly(ethylene oxide)--polyphosphoester-based paclitaxel drug conjugates (PEO--PPE--PTX) were synthesized by rapid, scalable and versatile approach that involves only two steps: organocatalyst-promoted ring-opening-polymerization followed by click reaction-based conjugation of a PTX prodrug. Variations in the polymer-to-PTX stoichiometries allowed for optimization of the conjugation efficiency, the PTX drug loading and the resulting water solubilities of the entire polymer and the PTX content.

pH-Triggered reversible morphological inversion of orthogonally-addressable poly(3-acrylamidophenylboronic acid)-block-poly(acrylamidoethylamine) micelles and their shell crosslinked nanoparticles.

Functionally-responsive amphiphilic core-shell nanoscopic objects, capable of either complete or partial inversion processes, were produced by the supramolecular assembly of pH-responsive block copolymers, without or with covalent crosslinking of the shell layer, respectively. A new type of well-defined, dual-functionalized boronic acid- and amino-based diblock copolymer poly(3-acrylamidophenylboronic acid)(30)-block-poly(acrylamidoethylamine)(25) (PAPBA(30)-b-PAEA(25)) was synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and then assembled into cationic micelles in aqueous solution at pH 5.5.