Focus Review

Combining gene therapy and tissue engineering, gene-activated matrix (GAM) is able to activate cells in or near the scaffolds to express the desired growth factors at effective levels within the local tissue microenvironment and further to restore the structure and function of damaged or dysfunctional tissues like skin, cartilage, bone, vessel, muscle, tendon and so on.

Fundamental development of nonfouling zwitterionic poly(sulfobetaine methacrylate) (polySBMA) coatings on a wide range of interfaces and membranes for use in the development of hemocompatible medical devices was discussed. The molecular designs of zwitterionic interfaces as well as the evolution of ‘intelligent’ interfaces and correlations between zwitterionic polymeric membrane surface modifications are scrutinized and delineated.

Smart polyplex micelles for systemic gene therapy fabricated by rationally integrating versatile molecular-based technologies. The polyplex micelles, which are formed through an electrostatic interaction-mediated self-assembly process of functional block copolymers and plasmid DNA, assume a task to transport therapeutic gene into nucleus of pathological cells via systemic route for functional protein expression.

Phenylboronic acid (PBA) derivatives are regarded as a synthetic mimic of lectins, often termed ‘boronolectins’, for its ability to interact with various carbohydrates. This unique chemistry has already borne fruit as molecular bases for glucose sensors and some bio-separation applications. This focus review highlights some emerging directions of the PBA-based research toward more versatile diagnostic and therapeutic targets that the authors currently pursue.

Tetra-PEG gel has highly suppressed heterogeneity, which is considered inherent to conventional polymer gels. In this review, we show a series of experimental results on Tetra-PEG gels, and discuss the homogeneity. Tetra-PEG gel is useful as a model system for examining the model predicting physical properties of polymer gels.

Both chain collapse below the θ-temperature (coil–globule transition) and chain aggregation below the cloud point were studied systematically with dilute solutions of poly(methyl methacrylate) (PMMA) quantitatively by light scattering experiments. Because of slow phase separation of the PMMA solutions in some polar solvents, the chain collapse process was measured without disturbance by the effect of chain aggregation. To examine the structure of a PMMA globule, an effect of temperature perturbation on the globule in the chain collapse process was investigated, and a phenomenon analogous to the memory effect of glassy materials was observed.

This review presents recent advances in the surface engineering of gold nanoparticles (AuNPs) applicable for their therapeutic use, with a particular focus on the following three topics: (1) surface design for enhanced cellular uptake, (2) capsule-like assembly of AuNPs for drug delivery and (3) engineering of AuNPs as vaccine adjuvants. We discuss the importance of surface ligands in regulating and enhancing cell–nanoparticle interactions toward the creation of smart therapeutic nanomaterials.

The interaction between synthetic particles and proteins has been studied to identify factors that govern the interaction in vitro. The composition and properties of the protein corona that forms on the surface of NPs have been studied in vivo. Recently, synthetic NPs that recognize target molecules are designed and prepared by optimizing the combination of functional groups on the particles, molecular imprinting, in combination with the affinity purification. Some particles are capable of recognizing target molecules and neutralizing their function, in the bloodstream of living animals, as ‘plastic antibodies.’

Here, the author summarizes recent development of stimuli-responsive synthetic polymers in ionic liquids (ILs) as a novel platform in designing intelligent soft materials. Owing to the versatile structure designability and unique properties of ILs, such as nonvolatility and wide liquid temperature range, soft materials consisting of polymer–IL combinations can be employed under an open atmosphere for long term, and can also permit wide operating temperature and pressure conditions without concern for solvent evaporation that has been a serious drawback of traditional soft materials.

This focus review summarizes advances in the recently emerging field of phenolic film engineering for template-mediated microcapsule preparation. By depositing polyphenol films on sacrificial particulate templates and subsequently removing the templates, hollow microcapsules can be readily prepared. Due to the pH-responsive properties, negligible cytotoxicity and the bioactivities of the phenolic building blocks (dopamine and tannic acid), phenolic microcapsules are promising for biomedical applications.

The universal control of cell functions at single-cell level through artificial modulation of extracellular microenvironments by mimicking the natural extracellular matrices (ECMs) would be a key technique for biomedical fields. In the present review, fabrication of nanometer-sized artificial ECM films using various polymers and proteins on single-cell surfaces to control cell functions is described. The simple coating techniques reported here have opened a new window as a key technique for control of the extracellular microenvironments in tissue engineering, pharmaceutical and pathophysiological fields.

Theoretical and/or Monte Carlo studies are made of dilute solution properties of semiflexible stars and rings based on the Kratky–Porod wormlike chain model. The behavior of the properties in the range of the crossover from the rigid limit to the random-coil one is clarified. It is shown that effects of chain stiffness affect largely the dilute solution behavior not only of linear polymers but also of stars and rings, and are still remarkable even for typical flexible polymers with large molecular weight (∼10⁵).

Partially crosslinked poly(diphenylacetylene) (3a) bearing silanol groups were synthesized by the treatment of the membrane of 2a with n-Bu₄N⁺F⁻. Imidazolium salt-containing poly(diphenylacetylene) (3b (Br⁻)) was obtained by the substitution of 1-methylimidazole to the membrane of 2b. Sulfonation of 2c gave a sulfonated poly(diphenylacetylene) (3c). The membrane of 3a was found to exhibit high gas permeability irrespective of the presence of the polar silanol groups in the polymer. Introduction of 1-methylimidazole into the membrane remarkably increased the CO₂/N₂ selectivity (P_CO2/P_N2=31–44). The sulfonated polymer 3c exhibited high CO₂ permselectivity, and the P_CO2/P_N2 was as large as 54.

This paper reviews the development of zincate-complex metathesis polymerization (ZCMP) and its application to protection-free direct synthesis of poly(3-(6-hydroxyhexyl)thiophene) as well as block copolythiophene. The modified ZCMP system using Ni(dcpe)Cl₂ as a catalyst accomplished the preparation of well-defined poly(3-hexylthiophene)s (P3HTs) (M_n up to 35 000 g mol⁻¹) with extremely low PDI (1.03∼1.11). In addition, the first example of all-conjugated block copolythiophene, P3HT-b-poly(3-octadecylthiophene), could be synthesized on the basis of the sequential monomer addition approach based on ZCMP.

Topologically crosslinked polymers with rotaxane structures at the crosslinking points (rotaxane-crosslinked polymers, RCPs) have attracted great interest experimentally and theoretically. This focus review describes recent progress concerning the synthesis and applications of RCPs via four strategic approaches. Related research topics and further perspectives on RCPs are also discussed.

This focus review describes a novel research concerning horseradish peroxidase (HRP)-mediated enzymatic polymerization under aqueous heterogeneous conditions as follows: (i) monodisperse polymer particles were prepared by enzymatic miniemulsion polymerization using surfmer (surfactant+monomer). (ii) Polymer particles stabilized by β-diketone moieties were prepared by enzymatic emulsifier-free emulsion polymerization. (iii) A novel method of surface-initiated enzymatic graft polymerization was used to synthesize core-shell particles.

Polyion complex (PIC) formation is one of the most powerful techniques for obtaining molecular self-assemblies in aqueous media, and useful for material syntheses particularly in the biomedical field. In this review article, recent progress on PIC vesicles (PICsomes) is summarized. PICsomes are characterized by their simple preparation, semipermeability and environment-sensitivity. Very recently, the methods to control structural uniformity and size of the vesicles have been established, and the potential utility of PICsomes has been expanded by crosslinking their PIC layers. In addition, the unique dynamic nature of PICs is also described.

The recent progress of research on polymer reactions utilizing dynamic covalent exchanges of alkoxyamine units—adducts of styryl and stable nitroxide radicals—is reviewed. Various types of macromolecular design, polymer reactions based on dynamic covalent exchanges of alkoxyamine units and their related research are described. Various examples of polymer reactions of main-chain-type, side-chain-type, crosslinked and star-shaped poly(alkoxyamine)s are systematically shown. The progress of the polymer reactions can be confirmed by diverse characterization techniques, such as spectroscopic, chromatographic, microscopic and scattering methods.

Isolated molecules of cyclic polymers were directly observed by atomic force microscopy. Interdiffusion of cyclic polystyrene/cyclic deuterated polystyrene bilayer films were investigated as functions of temperature and molecular weight by dynamic secondary ion mass spectroscopy.

The electrostatic self-assembly and covalent fixation (ESA-CF) process, in conjunction with click chemistry and olefin metathesis, was used to construct selectively a variety of unprecedented polymer architectures, such as manacle-shaped and tandem multicycles, as well as doubly fused tricyclic and triply fused tetracyclic topologies. Moreover, the self-assembly of a cyclic amphiphilic block copolymer, which was prepared by intramolecular metathesis, produced a micelle with an approximately 50 °C increase in thermal stability compared with the one from the linear prepolymer. Single-molecule spectroscopic studies also revealed different diffusion modes for cyclic and linear polymers.