Polymer Journal

Hanpanich, Orakan; Maruyama, Atsushi

doi: 10.1038/s41428-019-0210-7pmid: N/A

Accurate folding of biopolymers and assembly of complexes containing these molecules are essential for biological activities. We designed cationic comb-type copolymers that act as an artificial chaperone to assist in the folding of biopolymers such as nucleic acids and peptides. The copolymers consist of a polycation backbone grafted with a high density of hydrophilic chains that allow the formation of soluble and soft interpolyelectrolyte complexes between the copolymer and oppositely charged biopolymers. The copolymers can chaperone DNA assembly into duplex, triplex, and quadruplex structures and accelerate strand exchange reactions while stabilizing DNA complexes. This chaperone activity of the copolymer is useful in nucleic acid-based nanotechnological applications such as DNA nanomachines, DNA logic gates, and DNA enzymes. The cationic comb-type copolymers also assisted in the folding of functional peptides. The basic E5 peptide folds into an alpha-helical structure and exhibits a stronger membrane-disrupting activity in the presence of the copolymer than in its absence. The cationic comb-type copolymers, as an artificial chaperone, were shown to be beneficial for enhancing the functions and facilitating the application of biopolymers in nanotechnology and medicine.

Kakuchi, Ryohei

doi: 10.1038/s41428-019-0209-0pmid: N/A

This focus review documents the developments in polymer synthesis that involve multicomponent reactions (MCRs) and related sequential reaction systems. Postpolymerization modification and step-growth polymerization reactions based on MCRs and sequential reactions such as the Kabachnik–Fields three-component reaction (KF-3CR) are described.

Oda, Yukari

doi: 10.1038/s41428-019-0215-2pmid: N/A

The effect of polymer design on the interfacial structure and physical properties of polymer films in water based on a poly(vinyl ether) platform with hydrophilic side-chains was examined to construct bioinert interfaces. Hydrophilic surfaces were prepared by utilizing the preferential segregation of a rubbery component in a diblock copolymer film with a glassy component, crosslinking a hydrophilic polymer, and designing an interfacial modifier with a special architecture. Interfacial structure and physical properties controlled by polymer design play important roles in determining bioinert properties.

Kitayama, Yukiya

doi: 10.1038/s41428-019-0219-ypmid: N/A

Functionalized colloidal particles are fascinating due to their huge range of potential and reported applications. In this focus review, the recent development of a novel “interfacial photoreaction” for the preparation of functional polymer particles is summarized. Recently, we discovered the phenomenon of the interfacial selective cross-linking of spherical polymer particles bearing photoreactive groups, and this reaction was successfully used to synthesize hollow polymer particles. As these hollow polymer particles have a cross-linked shell, solvent exchange can lead to the posteriori encapsulation of various molecules, yielding capsule particles. Functionalization of hollow/capsule particles was successfully achieved by introducing functional groups to the parent spherical polymer particles. In addition, the spatially controlled interfacial photoreaction enabled the formation of non-spherical bowl-shaped polymer particles. Furthermore, the photoinduced interfacial cross-linking strategy was successfully combined with molecular imprinting, and functional polymer particles with a molecular recognition capability were developed by utilizing the novel photoinduced post-cross-linked molecular imprinting method. We believe that photoinduced interfacial cross-linking will allow for the creation of new functional polymer particles suitable for a range of versatile applications.

Inagi, Shinsuke

doi: 10.1038/s41428-019-0223-2pmid: N/A

This review focuses on recent developments in electropolymerization that use bipolar electrochemistry. A bipolar electrode (BPE), which is driven under the influence of an electric field, can be used for electrochemical reactions with interesting features such as wireless and site-selective reactions. In this context, bipolar electropolymerization is a powerful method for wirelessly achieving site-selective anisotropic modification of BPEs with conducting polymers. In addition, alternating current (AC) bipolar electropolymerization was developed to induce conducting polymer fibers from the terminals of BPEs that propagate parallel to the direction of the electric field. Bipolar electropolymerization is a class of next-generation electropolymerization for obtaining hybrid materials of conducting polymers and conductive objects.

Ube, Toru

doi: 10.1038/s41428-019-0224-1pmid: N/A

Crosslinked liquid-crystalline polymers (CLCPs) show macroscopic deformation along with a change in molecular order, which is triggered by various stimuli such as heat, electricity, and light. CLCPs containing photochromic moieties are realizable as photoresponsive soft actuators. This review focuses on recent developments in novel network structures of CLCPs: rearrangeable networks and interpenetrating polymer networks (IPNs). CLCPs with dynamic covalent bonds could be reshaped into 3D architectures through the rearrangement of the network topology, in contrast with conventional crosslinked polymers memorizing permanent shapes. The reshaped samples showed various photoinduced motions depending on their initial shapes. Furthermore, amorphous polymers were incorporated into conventional CLCP networks to control mechanical and photoresponsive properties. The sequential formation of CLCP and amorphous polymer networks resulted in IPN films with a homogeneous alignment of mesogens. The elastic moduli of IPN films were controlled through the selection of amorphous components. The incorporation of soft components such as poly(dodecyl methacrylate) and poly(dimethylsiloxane) (PDMS) significantly enhanced the rate of photoinduced bending. These strategies of controlling the network structures of CLCPs could enable the versatile design of photomobile polymer materials as soft actuators with desired architectures and functions.

Hara, Mitsuo

doi: 10.1038/s41428-019-0214-3pmid: N/A

As a preparation method for organic–inorganic or mesoporous inorganic materials via sol–gel condensation of a metal alkoxide, the combination of lyotropic liquid crystals (LLCs) and sol–gel chemistry is a versatile tool to fabricate various nanostructures. Despite previous investigations into such systems, no attempt has been made to utilize the dynamic switching functions of such nanostructures via the phase transition of LLCs in films. A polysiloxane containing an amine-hydrochloride group and a vinyl group was recently synthesized. By controlling the relative humidity, we achieved the phase transition of LLCs and on-demand UV-curing of LLC phases in the polysiloxane film. We further developed vertically oriented organic–inorganic nanochannels by using π−π interactions between discotic molecules and the substrate surface or the spontaneous vertical alignment of LLC containing azobenzene units.

Ohya, Yuichi

doi: 10.1038/s41428-019-0217-0pmid: N/A

Biodegradable injectable polymers (IPs) that exhibit temperature-responsive sol–gel transitions have recently drawn much attention as promising biomedical materials, such as in drug delivery systems, cell implantation, and tissue engineering. Typical examples of temperature-responsive IPs are block copolymers of poly(ethylene glycol) (PEG) and aliphatic polyesters. The use of biodegradable IP systems in clinical applications has faced several issues. In this review, after a brief introduction of IP systems, our recent progress on controllable IP systems using simple mixing strategies is introduced. Control of the gelation pH region of a dual-stimuli (both temperature and pH)-responsive IP system was achieved by changing the mixing ratio of cationic and anionic polymers. Temperature-triggered covalent (irreversible) gelation systems were developed by mixing IPs with reactive termini and appropriate cross-linker molecules. The duration of the gel state (decomposition period) of IP hydrogels was easily controlled by changing the mixing ratio of the components. The developed biodegradable IP systems with controllable properties are promising for future applications in clinical stages.

Kihara, Nobuhiro; Yanaze, Kazuya; Yokoyama, Satoshi; Kaneko, Moe

doi: 10.1038/s41428-019-0220-5pmid: N/A

Bulk copolymerization of bis(acryloylhydrazine) with N,N-dimethylacrylamide or N,N-diethylacrylamide yielded a transparent crosslinked polymer monolith. Upon treatment with a sodium hypochlorite solution, the cross-linked monolith dissolved in water by de-crosslinking via oxidative degradation of the diacylhydrazine moiety.

Tsuji, Sotaro; Aso, Yuji; Ohara, Hitomi; Tanaka, Tomonari

doi: 10.1038/s41428-019-0221-4pmid: N/A

Novel polymer backbones with water-soluble activated ester pendant groups were synthesized by a reversible addition-fragmentation chain transfer (RAFT) polymerization technique using an acrylamide derivative bearing an N-hydroxysulfosuccinimide (sulfoNHS) ester as a monomer substrate. The monomer bearing a sulfoNHS ester was newly synthesized by a dehydrative condensation reaction of N-hydroxysulfosuccinimide sodium salt with 6-acrylamidohexanoic acid. The molecular weight and polydispersity indexes of the resulting polymers were well controlled by the RAFT polymerization mechanism. To synthesize glycopolymers, the substitution of the sulfoNHS esters on the polymer side chain with an amine-containing saccharide derivative, p-aminophenyl β-d-galactopyranoside (pAP-Gal), was performed in water. The resulting glycopolymer bearing pAP-Gals exhibited a strong interaction with the corresponding lectin peanut agglutinin in aqueous solution, because the saccharide moieties are multivalent.