Supramolecular inclusion complexes of star-shaped poly(ε-caprolactone) with α-cyclodextrin

The study of the pseudo-polyrotaxane architecture as a route for mild surface functionalization by click chemistry of poly(ε-caprolactone)-based electrospun fibers

PCL fibers with pseudopolyrotaxanes at their surface are functionalized with bicyclononyne clickable groups making possible an easy bioconjugation in water and without copper catalysts for biomedical applications.

Synthesis and characterization of high grafting density bottle-brush poly(oxa)norbornene-g-poly(ε-caprolactone)

The synthesis and the ring-opening metathesis polymerization of well-defined poly(ε-caprolactone)-based (oxa)norbornene macromonomers bearing two poly(ε-caprolactone) chains on the polymerizable entity are reported.

Synthesis and characterization of novel barbwire-like graft polymers poly(ethylene oxide)-g-poly(ε-caprolactone)4 by the ‘grafting from’ strategy

Novel barbwire-like graft polymers PEO-g-PCL₄ were synthesized by combination of ring opening polymerization (ROP) and Glaser coupling with thiol–yne addition reaction via the “grafting from” strategy.

Aliphatic polyester polymer stars: synthesis, properties and applications in biomedicine and nanotechnology

A critical review: the ring-opening polymerization of cyclic esters provides access to an array of biodegradable, bioassimilable and renewable polymeric materials. Building these aliphatic polyester polymers into larger macromolecular frameworks provides further control over polymer characteristics and opens up unique applications. Polymer stars, where multiple arms radiate from a single core molecule, have found particular utility in the areas of drug delivery and nanotechnology. A challenge in this field is in understanding the impact of altering synthetic variables on polymer properties. We review the synthesis and characterization of aliphatic polyester polymer stars, focusing on polymers originating from lactide, ε-caprolactone, glycolide, β-butyrolactone and trimethylene carbonate monomers and their copolymers including coverage of polyester miktoarm star copolymers. These macromolecular materials are further categorized by core molecules, catalysts employed, self-assembly and degradation properties and the resulting fields of application (262 references).

Peptide-functionalized poly(ethylene glycol) star polymers: DNA delivery vehicles with multivalent molecular architecture

Exploring the development of nonviral nucleic acid delivery vectors with progressive, specific, and novel designs in molecular architecture is a fundamental way to investigate how aspects of chemical and physical structure impact the transfection process. In this study, macromolecules comprised of a four-arm star poly(ethylene glycol) and termini modified with one of five different heparin binding peptides have been investigated for their ability to bind, compact, and deliver DNA to mammalian cells in vitro. These new delivery vectors combine a PEG-derived stabilizing moiety with peptides that exhibit unique cell-surface binding ability in a molecular architecture that permits multivalent presentation of the cationic peptides. Five peptide sequences of varying heparin binding affinity were studied; each was found to sufficiently bind heparin for biological application. Additionally, the macromolecules were able to bind and compact DNA into particles of proper size for endocytosis. In biological studies, the PEG-star peptides displayed a range of toxicity and transfection efficiency dependent on the peptide identity. The vectors equipped with peptides of highest heparin binding affinity were found to bind DNA tightly, increase levels of cellular internalization, and display the most promising transfection qualities. Our results suggest heparin binding peptides with specific sequences hold more potential than nonspecific cationic polymers to optimize transfection efficiency while maintaining cell viability. Furthermore, the built-in multivalency of these macromolecules may allow simultaneous binding of both DNA at the core of the polyplex and heparan sulfate on the surface of the cell. This scheme may facilitate a bridging transport mechanism, tethering DNA to the surface of the cell and subsequently ushering therapeutic nucleic acids into the cell. This multivalent star shape is therefore a promising architectural feature that may be exploited in the design of future polycationic gene delivery vectors.

Guest-free self-assembly of alpha-cyclodextrins leading to channel-type nanofibrils as mesoporous framework

Guest-free alpha-cyclodextrin self-assembly (alpha-CD-SA) was successfully obtained through a simple treatment such as sonication of alpha-CD in a specific solvent. From wide-angle X-ray diffraction (WAXD), it was found that the crystalline structure of alpha-CD changed upon increasing the treatment time, resulting in alpha-CD-SA in which the alpha-CDs were closely packed in the vertical direction and hexagonally aligned in the horizontal direction (what is called as "channel structure"). In particular, these structures were developed only in tetrahydrofuran (THF) as a specific solvent. In addition, it was found by inclusion experiment and field-emission scanning electron microscopy (FE-SEM) that propionic acid was able to be included into the channel of alpha-CD-SA and that alpha-CD-SA had alpha-CD bundles with a fibril-like shape, respectively. These results demonstrate that the alpha-CD-SA consists of nanofibril-like alpha-CD bundles with cylindrical nanopores open at least at one end, resulting from the dispersion of alpha-CD molecules by sonication in THF and the subsequent re-formation of strong hydrogen bonding between the alpha-CDs with the aid of THF (so-called "slow recrystallization"). Interestingly, it was observed from FE-SEM and nitrogen adsorption-desorption measurement that the alpha-CD-SA had a wormhole-like mesopore with inkbottle shape (average desorption pore size = ca. 25 nm). This mesoporous structure was considered to be attributed to the formation of a mesoporous framework by the disordered aggregation of the nanofibril-like alpha-CD bundles.