Carbohydrate-appended curdlans as a new family of glycoclusters with binding properties both for a polynucleotide and lectins

Beta-1,3-glucans having carbohydrate-appendages (alpha-D-mannoside, N-acetyl-beta-D-glucosaminide and beta-lactoside) at the C6-position of every repeating unit can be readily prepared from curdlan (a linear beta-1,3-glucan) through regioselective bromination/azidation to afford 6-azido-6-deoxycurdlan followed by chemo-selective Cu(i)-catalyzed [3 + 2]-cycloaddition with various carbohydrate modules having a terminal alkyne. The resultant carbohydrate-appended curdlans can interact with polycytosine to form stable macromolecular complexes consistent with two polysaccharide strands and one polycytosine strand. Furthermore, these macromolecular complexes show strong and specific affinity toward carbohydrate-binding proteins (lectins). Therefore, one can utilize these carbohydrate-appended curdlans as a new family of glycoclusters.     

Complex formation between cationic beta-1,3-glucan and hetero-sequence oligodeoxynucleotide and its delivery into macrophage-like cells to induce cytokine secretion

A cationic polysaccharide bearing a beta-1,3-glucan main-chain structure (CUR-N(+)) forms a complex with a hetero-sequence oligonucleotide, that is, a CpG ODN, and facilitates the transportation of the resultant complex into a murine macrophage-like cell J774.A1, which induces an efficient secretion of a cytokine (IL-12) as compared with that induced by conventional carriers such as poly(ethyleneimine) (PEI) and poly(L-lysine) (PLL).     

Iterative two-step strategy for C2-C4′ linked poly-oxazole synthesis using Suzuki-Miyaura cross-coupling reaction

An iterative method for the synthesis of C2-C4′ linked poly-oxazoles has been developed. This efficient two-step repetitive process includes TBS-iodine exchange reaction and Suzuki-Miyaura cross-coupling reaction with oxazolylboronate 8, which allows appending a bis-oxazole moiety per each iteration. The synthesis of bis-, tris-, tetrakis-, pentakis-, and hexakis-oxazoles (10, 14, 22, 18, and 24) was achieved starting from the common intermediate 7 in 1-5 steps.     

Enantioselective total synthesis of (+)-ottelione A, (-)-ottelione B, (+)-3-epi-ottelione A and preliminary evaluation of their antitumor activity

Enantioselective total synthesis of (+)-ottelione A (1) and (-)-ottelione B (2), novel and potent antitumor agents from a freshwater plant, and (+)-3-epi-ottelione A (3), the earlier proposed stereostructure of 1, was efficiently achieved starting from the known tricyclic compound 10. The synthesis involved the following key steps: i) coupling reactions of aldehydes 8 and 9 with the aromatic portion 7 (8+7-->15 and 9+7-->27), ii) base-induced hemiacetal-opening/epimerization reactions of the cyclic hemiacetals 6 and 27 (6-->17 and 27 a-->26 a), and iii) Corey-Winter's reductive olefination of the cyclic thiocarbonates 21 and 36 (21-->22 and 36-->37). The present total synthesis fully established the absolute configuration of these natural products. The cell growth inhibition profile, COMPARE analysis, and tubulin inhibitory assay of (+)-3-epi-ottelione A (3) and its O-acetyl derivative 24 demonstrated that these unnatural substances could be prominent lead compounds for the development of anticancer agents with a novel mode of action.     

“Supramolecular” Amphiphiles Created by Wrapping Poly(styrene) with the Helix‐Forming β‐1,3‐Glucan Polysaccharide

We have demonstrated that giant polymer micelles with a uniform diameter (ca. 200 nm) can be fabricated by “supramolecular wrapping” of poly(styrene) (PS) with the β‐1,3‐glucan polysaccharide, with the β‐1,3‐glucan fastening the PS chains together in a noncovalent fashion to facilitate the formation of a supramolecular polymer network on the O/W emulsion surface. Various spectroscopic and microscopic investigations have revealed that the inner cores of the micelles are comprised of a hydrophobic PS network, whereas the surfaces consist of a hydrophilic β‐1,3‐glucan layer. Accordingly, functional guest molecules can easily be encapsulated inside the cavity through hydrophobic interactions. The encapsulated molecules can simply be released from the micelle cores by peeling off the β‐1,3‐glucan shell in a supramolecular manner. As functional groups can be introduced into the glucose side‐chain unit in a straightforward manner by chemical modification, the micellar surface can acquire further functions useful for molecular recognition. These results show that the micelles obtained could have applications as novel soft nanoparticles, which would be indispensable not only for nanotechnologies, but also for biotechnologies aimed at gene or drug delivery systems.     

Multichain copoly(α-amino acid). I. Multichain copoly(α-amino acid) prepared by reaction of copoly(L-lysine γ-methyl-L-glutamate) with N-carboxy anhydride of Nϵ-carbobenzyloxy-L-lysine

Polymerization of the N-carboxy anhydride of N^?-carbobenzyloxy-L -lysine in the presence of multifunctional polymeric initiator, copoly(L -lysine γ-methyl-L -glutamate) was studied in N,N-dimethylformamide containing 3% (v/v) of dimethyl sulfoxide. Multichain copoly(α-amino acid), i.e., multi-N^?-poly(N^?-carbobenzyloxy-L -lysine)copoly(L -lysine γ-methyl-L -glutamate), was obtained with linear poly(N^?-carbobenzyloxy-L -lysine) as by-product that could be removed by reprecipitation as was evidenced by gel-permeation chromatography. The degree of polymerization of the branch polymer chains estimated by the osmometric molecular weight determination and amino acid analysis was between 20 and 60, which decreased with increasing lysine content of the polymeric initiator. The stability of α-helical conformation of the multichain copoly(α-amino acid) was studied in the chloroform–dichloroacetic acid system at 25°C by the ORD technique. The α-helical conformation of poly(N^?-carbobenzyloxy-L -lysine) branches was less stable than those of linear poly(N^?-carbobenzyloxy-L -lysine) and the core molecular chains of the multichain copoly(α-amino acid).     

Beta-1,3-glucan (schizophyllan) can act as a one-dimensional host for creation of novel poly(aniline) nanofiber structures

We here demonstrate the creation of novel poly(aniline) (PANI) nanofiber structures by a polymer wrapping method using schizophyllan (SPG). Mannose-modified SPG can also wrap PANIs to give nanofibers having a lectin affinity. This interaction is applicable to designing novel PANI/protein composites. The results establish that SPG can act as a novel "host" to assemble PANIs into one-dimensional superstructures. [reaction: see text]     

Enhanced adhesion of copper plating to polyether ether ketone based on active oxygen species generated under ultraviolet irradiation

Polyether ether ketone (PEEK) is a substrate for metal plating to overcome insulation defects and satisfy the increased demands of mechanically robust electronic circuit boards. However, pristine PEEK is hydrophobic; hence, the adhesion between the metal film and PEEK substrate is poor. Therefore, the PEEK surface should be modified to improve hydrophobicity. We have proposed the active oxygen (AOS) treatment under ultraviolet (UV) light as an alternative to a conventional plasma treatment method. Characteristics of the PEEK surfaces obtained by these methods are compared. We explore the effects of reactive-oxygen and UV light exposure time on the PEEK surface modification. The contact angle of water drop on PEEK after the AOS treatment is lower than that of untreated PEEK. Furthermore, COO groups are observed on the PEEK surface after the treatment. Although plasma treatment has the effect of roughening the surface, it is desirable not to roughen the surface for use in electronic circuit boards. Moreover, we have reported the adhesion strength between PEEK and copper plating without surface roughening.     

Supramolecular Chemistry in Microflow Fields: Toward a New Material World of Precise Kinetic Control

Constructing new and versatile self‐assembling systems in supramolecular chemistry is much like the development of new reactions or new catalysts in synthetic organic chemistry. As one such new technology, conventional supramolecular assembly systems have been combined with microflow techniques to control intermolecular or interpolymer interactions through precise regulation of a flowing self‐assembly field. The potential of the microflow system has been explored by using various simple model compounds. Uniform solvent diffusion in the microflow leads to rapid activation of molecules in a nonequilibrium state and, thereby, enhanced interactions. All of these self‐assembly processes begin from a temporally activated state and proceed in a uniform chemical environment, forming a synchronized cluster and resulting in effective conversion to supramolecules, with precise tuning of molecular (or polymer) interactions. This approach allows the synthesis of a variety of discrete microstructures (e.g., fibers, sheets) and unique supramolecules (e.g., hierarchical assemblies, capped fibers, polymer networks, supramolecules with time‐delayed action) that have previously been inaccessible.