Synthesis and self-assembly of thermo/pH-responsive double hydrophilic brush–coil copolymer with poly(l-glutamic acid) side chains

Ring opening polymerization of α-amino acids: advances in synthesis, architecture and applications of polypeptides and their hybrids

This review provides a comprehensive overview of the latest advances in the synthesis, architectural design and biomedical applications of polypeptides and their hybrids.

Construction of a thermo-responsive copolymer-stabilized Fe3O4@CD@PdNP hybrid and its application in catalytic reduction

A thermo-responsive copolymer stabilized Fe₃O₄@CDs@PdNP hybrid was fabricated as a nanocatalyst for catalytic reduction reaction with excellent recyclability and controllable thermo-responsive catalytic property.

Mussel-inspired construction of thermo-responsive double-hydrophilic diblock copolymers-decorated reduced graphene oxide as effective catalyst supports for highly dispersed superfine Pd nanoparticles

Well-dispersed ultrafine palladium nanoparticles supported by reduced graphene oxide functionalized with catechol-terminated thermo-responsive block copolymer (PdNPs@BPrGO) were successfully constructed for highly efficient heterogeneous catalytic reduction. We first synthesized a novel temperature-responsive episulfide-containing double-hydrophilic diblock copolymer, poly(poly(ethylene glycol) methyl ether methacrylate-co-2,3-epithiopropyl methacrylate)-block-poly(N-isopropylacrylamide) (P(PEGMA-co-ETMA)-b-PNIPAM), through a reversible addition-fragmentation chain transfer (RAFT) polymerization utilizing a chain-transfer agent with a catechol unit as the end group. The obtained block copolymers can be facilely anchored to the surface of GO via mussel-inspired chemistry. The PdNPs were loaded on GO decorated with block copolymer brushes (BPrGO) as a support via the in situ reduction of palladium precursors with the episulfide ligands of the block copolymer as a stabilizer. The resulting PdNPs@BPrGO nanohybrid catalyst had good water dispersibility and stability. Furthermore, a low dosage of PdNPs@BPrGO catalyst exhibited excellent catalytic performance in the reduction of methylene blue and nitrophenols. The performance was attributed to the ability of PdNPs@BPrGO to facilitate the diffusion of reactants compared to PdNPs@GO without polymer modification. PdNPs@BPrGO also possessed an interesting temperature-responsive catalytic property due to the reversible "coil-to-globule" phase transition behaviour of PNIPAM blocks onto the surface of catalyst. The PdNPs@BPrGO catalyst was successfully recovered and reused five times without any detectible loss in catalytic activity, demonstrating its great potential in a wide range of industrial catalytic applications.

Polypeptide self-assemblies: nanostructures and bioapplications

Polypeptide copolymers can self-assemble into diverse aggregates. The morphology and structure of aggregates can be varied by changing molecular architectures, self-assembling conditions, and introducing secondary components such as polymers and nanoparticles. Polypeptide self-assemblies have gained significant attention because of their potential applications as delivery vehicles for therapeutic payloads and as additives in the biomimetic mineralization of inorganics. This review article provides an overview of recent advances in nanostructures and bioapplications related to polypeptide self-assemblies. We highlight recent contributions to developing strategies for the construction of polypeptide assemblies with increasing complexity and novel functionality that are suitable for bioapplications. The relationship between the structure and properties of the polypeptide aggregates is emphasized. Finally, we briefly outline our perspectives and discuss the challenges in the field.

pH-responsive nanoparticle assembly from peptide amphiphiles for tumor targeting drug delivery

In this paper, the peptide amphiphiles (PA) which consists of RGDSEEEEEEEEEEK as pH-sensitive segment and stearic acid as hydrophobic segment named RGDS-E₁₀-Lys(C₁₈) was successfully synthesized. TEM images showed that uniformly dispersed nanoparticles could be formed by PA molecules in pH 7.4 medium, however, disintegrated in pH 5.0 medium. Circular dichroism (CD) spectrum indicated that polypeptide adopted a random-coil conformation in neutral medium (pH 7.4). The CD signal was significantly attenuate for decreased solubility of PA in medium with pH 5.0. As expected, the prepared RGDS-E₁₀-Lys(C₁₈) assembly showed high pH-sensitive property which demonstrated a much more rapid drug release from micelles in tumor tissue (acidic environment) than in physiological environment (neutral environment). After DOX-loaded micelles incubated with tumor cells, the cytotoxicity of the micelles against Hela cells was increased obviously, indicating the great potential of micelles developed here as promising vehicle for targeted pH-responsive drug delivery.

Post-polymerization modification reactions of poly(glycidyl methacrylate)s

Single and multiple post-polymerization modifications of poly(glycidyl methacrylate) scaffold through the nucleophilic ring-opening reactions of the pendent epoxide groups are described.

Self-Assembly of an Amphiphilic OEG-Linked Glutamide Lipid

Amphiphilic peptides with or without oligoethylene glycol (OEG) chains based on 3,4-bis(benzyloxy)benzoic-linked glutamide were designed and their self-assembly was investigated. It was found that the amphiphilic peptide 3 with OEG chains could not only form stable gels in a wide range of solvents, but also showed better solubility in solvents than those without OEG chains. Fibrillar and nanotube structures were found in the gels formed and the width of the fibres could be tuned with added water content. The UV-vis and XRD results suggested that the driving forces for the peptide self-assembly were mainly intermolecular π–π and hydrogen-bonding interactions. These results provide a deeper understanding of the self-assembly mechanism and size control of nanofibrils formed by an OEG-based amphiphilic peptide.

Facile synthesis of thermo-responsive episulfide group-containing diblock copolymers as robust protecting ligands of gold nanoparticles for catalytic applications

Well-defined novel thermo-responsive diblock copolymers containing episulfide ligand stabilized Au NPs show interesting assembly morphologies, excellent colloidal stability and high catalytic activity for the reduction of 4-nitrophenol.

First double hydrophilic graft copolymer bearing a poly(2-hydroxylethyl acrylate) backbone synthesized by sequential RAFT polymerization and SET-LRP

This article reports the first synthesis of well-defined double hydrophilic graft copolymers with a PHEA backbone, by the combination of RAFT polymerization, SET-LRP, and a grafting-from strategy.

Double-channel emission from gold nanoparticles functionalized with a thermo-responsive copolymer ligand: preparation, optical properties and control of catalytic activity

Double-channel-emitting gold nanoparticles functionalized with a thermo-responsive copolymer ligand containing an episulfide group show a controllable thermo-responsive catalytic reduction performance for 4-nitrophenol.

POSS semitelechelic Aβ17–19 peptide initiated helical polypeptides and their structural diversity in aqueous medium

Polyhedral oligomeric silsesquioxane (POSS) semitelechelic Aβ_17–19 peptide which initiated polymerization of γ-benzyl l-glutamate N-carboxyanhydride (BLG-NCA) was studied to prepare peptide–polypeptide conjugates with α-helical conformation.

New strategy for controlled release of drugs. Potential pinpoint targeting with multiresponsive tetraaniline diblock polymer vesicles: site-directed burst release with voltage

A series of amphiphlic diblock polymers, tetraaniline block with different length of poly(N-isopropylacrylamide) (TA-b-PNIPAM), have been successfully synthesized. In a suitable solution, the as-synthesized diblock polymers can form stable large compound vesicles (LCVs) with multiple bimolecular-layer structure through self-assembly. These factors, such as the block length, different organic solvent, solvent ratio, pH value, temperature, and voltage, which affect the morphology and properties of the assembled aggregates, are systematically investigated. When the degree of polymerization of PNIPAM block is close to 10, the as-synthesized diblock polymer may form stable LCVs with the uniform size as well as few defects in the mixed solvent of dimethylformamide/water (v/v = 3:7). The assembled LCVs possess the properties of triple-responsive capacity on temperature, pH, and voltage. Variation in any of these factors can cause some changes in the morphology of LCVs. The drug release properties for doxorubicin (DOX) loaded by LCVs affected by temperature, voltage, and different pH values have been investigated. It is interesting that the structure of LCVs can be destructed completely by applying a voltage at 0.6 V. With such an advantage, the drugs loaded by the LCVs could burst release into designated place by using appropriate circuit design or instrument, thus achieving maximum efficacy of the loaded drugs or other bioactive molecules without any unnecessary chemical substances added. This approach allows us to concentrate more on material design aspects only, without regard to the complex targeting issue which is the biggest obstacle of such materials in practical applications.