Browse Articles

The recent studies on the development of polymeric core crosslinked particles for drug delivery system are reviewed. The first part of this article describes synthesis of polymeric core crosslinked particles via the formation of nanoemulsion, characterization of the particle structure using small angle scattering techniques, and effect of polymer chain conformation on the particle pharmacokinetics and pharmacodynamics. The second part introduces zwitterionic amino acid polymer (ZAP)-based core crosslinked particles and discusses some advantages of using ZAPs as a pilot macromolecule for cancer-targeting chemotherapy.

Anionic initiator systems for styrene polymerization were prepared via desilylation of benzylsilanes with metal alkoxides. Benzyltrimethylsilyl anions as the anionic polymerization initiators were obtained from benzylsilanes and potassium tert-butoxide at 70 °C in the absence of 18-crown-6. On the other hand, in the presence of 18-crown-6, benzyl anions were obtained at −78 °C. Subsequent addition of the styrene monomer to these initiators yielded polystyrenes. With the addition of 1,1-diphenylethylene (DPE) to the initiator system containing 18-crown-6, the corresponding DPE adduct was obtained.

A novel polymer material PEDOT:DBSA was prepared using oxidative polymerization and was modified by cross-linker GOPS and H₂SO₄-posttreatment. This material exhibits biocompatibility toward cell culture comparable to the glass substrate. The cross-linking process resulted in complete stabilization of PEDOT:DBSA thin film in an aqueous environment, whereas such stabilization was achieved even without high-temperature treatment. The model OECT device proved that the proposed material possesses electrical properties comparable to or even better than other organic mixed conductors used for transistors. This all shows a great potential of PEDOT:DBSA for bioelectronics applications.

Photoresponsive molecular amphiphiles have been incorporated into distinct soft materials to control properties in high temporal and high spatial manners. We demonstrate molecular azobenzene amphiphiles for construction of chiral supramolecular assemblies with excellent photoresponsibility and a high capacity for supramolecular transformation in aqueous media. Supramolecular chiral structures of azobenzene amphiphiles can assemble from microscopic to macroscopic length scales

Quantifying the interfacial energy of a polymer–liquid interface is challenging. We previously succeeded in analyzing the interfacial energy of a dynamic polymer brush interface by measuring the deformation of an ultrathin elastomer film floating on water. However, the quantitativity remains debatable because the bulk modulus was used. In this study, we reanalyze the interfacial energy using the ultrathin-film modulus. Large negative interfacial energy was observed for the system of high-density stretched brushes. The free energy balance for the system floating on water was calculated, validating the negative interfacial energy.

In our study, a continuous change of tensile strength (26.9–49.5 MPa) and impact strength (4.7–23.2 KJ/m²) of iPP samples is successfully accomplished without the specific catalysts. The high content of γ-crystal with thin lamellar thickness related to the ductility property is also experimentally confirmed. A morphology of the diagram is proposed based on the composition and molded technology.

Here, we introduce a candidate material, water-soluble guanidinylated chitosan (WGCS), for a protein delivery system. WGCS composed of 48.2% guanidinylated chitosan, 20.6% chitosan, and 31.2% chitin units was prepared from low-molecular-weight chitosan (CS). WGCS showed ca. 2.5-fold higher internalization into HeLa cells than CS does. Moreover, we found that WGCS significantly enhanced the internalization of bovine serum albumin in transport medium at pH 7.4.

While the physical properties of polymer solution have been extensively investigated, less is explored at the vicinity of vitrification due to the experimental difficulty. In this study, we analyzed polymerization-induced vitrification during bulk polymerization of methyl methacrylate. Dielectric spectroscopy captured vitrification caused by the change of polymer concentration at a constant temperature. Our study shows that the polymerization solution becomes heterogeneous at the vicinity of vitrification. In addition, this heterogenization coincides with the reaction acceleration classically known as the Trommsdorff effect.

Two specific concepts have emerged in the field of materials science over the last several decades: nanosheets and supramolecular polymers. Based on this background, supramolecular nanosheets, in which these two concepts are integrated, have recently attracted particular attention. This review focuses on design of two supramolecular nanosheets. One is tubulin protein-based supramolecular nanosheet for applications to GTP-responsive drug delivery system. The other is phospholipid-based supramolecular nanosheets and their applications in blood-administrated drug delivery systems.

Cashew nut shell liquid (CNSL) is a natural phenolic compounds that is non-edible biomass. A novel diglycidyl ether (BCNDGE) derived from CNSL was synthesized and used as a building block to formulate an epoxy resin. Epoxy resins were cured from BCNDGE and commercial diglycidyl ether (BPADGE) with acid anhydride hardener. BCNDGE content improved the thermal stability and flexibility of the epoxy compared with commercial BPADGE-based epoxy. Hence, BCNDGE is a promising novel diglycidyl ether candidate with high biomass content to act as an alternative to petroleum-based chemicals for epoxy resins.

In this review, the advantages associated with the molecular design of peptides as multifunctional templates for mineralization are initially described. Subsequently, the mechanisms of CaCO₃ nucleation and selective crystal growth achieved under biomimetic mineralization conditions using the designed peptide templates are discussed. Finally, the functional design of peptide–inorganic hybrid materials based on structural control and the use of a mineralization method that can be applied in the engineering and medical fields is considered from the viewpoint of the molecular properties of the peptides.

The coil-to-globule-to-coil transitions of a zwitterionic polymer, poly(2-[(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonio]acetate) (PCB2), in water, ethanol, and water–ethanol mixed solvents were investigated and compared with those of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC). PCB2 showed cononsolvency in water–ethanol mixed solvents with specific ethanol volume fractions. PCB2 showed a broader cononsolvency range than PMPC because of its lower association constants of water and ethanol and the marked competition for hydrogen bonding. The zwitterion-specific cononsolvency characteristics were rationalized with the electrostatic potentials and van der Waals energies of the zwitterions.

Supramolecular chiral emergence from achiral molecules is studied using newly designed amphiphilic polypeptides upon self-assembling into nanosheets and vesicles in water. The polypeptide, SL-π-D, contains a hydrophilic poly(Sar) block, two hydrophobic helical blocks, and a π-conjugate block. The helical blocks possess right- and left-handed helices, compensating for helical chirality resulting in an achiral molecule. SL-π-D self-assembled in trifluoroethanol/water solutions into uniform nanosheets and vesicles, with the Cotton effect appearing in the achiral π-conjugate block. Supramolecular chiral emergence intrinsically arises from the molecular structure and is enhanced in vesicular morphology.

Bis(3-aminopropyl)-DDSQ was employed for polymerization with various aromatic dialdehydes to obtain poly(azomethine)s with high double-decker-shaped phenylsubstituted silsesquioxane (DDSQ) contents in the main chain. Introducing the flexible propylene linkers in the DDSQ unit provided flexible and optically transparent free-standing films. Their mechanical properties were highly dependent with the structures of the dialdehyde co-monomers.

The melting temperature of the isothermally crystallized poly(trimethylene terephthalate) (PTT) lamellar stack structure was determined by X-ray measurements. The equilibrium melting temperature of PTT was determined to be 290.5 °C from the relationship between the melting temperature and the lamellar thickness. The temperature dependence of the lamellar thickness below T_c = 173.7 °C suggested crystallization through a mesophase. The temperature dependence of the growth rate was explained by secondary nucleation theory over a wide crystallization temperature range.

Nucleobase modification of acyclic XNA oligomers achieved functionalization for use as a novel fluorescent probe and photoswitching system. A linear probe, composed of serinol nucleic acid (SNA) and 5-perylenylethynyl uracil residues, enabled quantitative detection of target RNA through a visually observable change in fluorescent color and intensity. A photoresponsive SNA with two 8-pyrenylvinyl adenine (^PVA) residues established photocontrol of SNA/RNA duplex formation and dissociation. Using a combination of 8-naphthylvinyl adenine (^NVA) and ^PVA demonstrated orthogonal photocontrol system. Thus, nucleobase modifications further expand the utility of acyclic XNA in bionanotechnology.

We review our recent studies in which the optical functions of monomers and π-conjugated polymers are precisely controlled based on flexible heteroatom-containing complexes. The combination of heteroatoms, such as boron, nitrogen, oxygen, and fluorine, creates slightly bent and asymmetric structures against π-surfaces, which induce bending motion in the excited state, providing solid-state luminescence and stimuli-responsive properties. Furthermore, the structures enable π-conjugation to be extended, and the optical functions are finely tuned by polymerization, which restricts the flexibility along the polymer main chain. Our strategy provides novel insights for the development of π-conjugated polymers showing unprecedented functionalities.

We investigated the effect of the hydrophobicity of the side chains of mixed-charge polymers on their interaction with cancer cell membranes. Six pH-responsive mixed-charge polymeric micelles consisting of cationic, anionic, and neutral moieties were created, with differences in hydrophobicity generated by altering the type of anionic monomer and the ratio of the hydrophobic spacer moiety. Evaluation of their affinity for cell membranes revealed that increases in the hydrophobicity and pH-responsive nature led to pH-selective toxicity, which was assumed to be caused by the disruption of cell membrane integrity.

Time-resolved FTIR was used to study the crystallization kinetics of syndiotactic polystyrene. Isothermal crystallization from the melt by cooling and from the glass by heating was used to determine the temperature (T_c) dependence of the crystallization rate (k). Based on the derived k and the crystal growth rates (G) obtained from OM and depolarized light scattering, the density of primary nucleation was readily calculated. The magnitudes of the nucleation densities in the cold-crystallized samples were ~5−6 orders higher than those of the melt-crystallized samples despite the similar k values.