Review

The morphology and the electronic conductive properties of self-assembled monolayers formed by helical oligopeptides suitably functionalized with electro- and photoactive units were investigated by electrochemical, spectroscopic and atomic force microscopy techniques. The versatility of peptide building blocks was also highlighted by the formation of bicomponent self-assembled monolayers exploiting interchain dipole–dipole interactions.

Theranostic agents based on nanovectors (liposomes, naposomes, micelles, polymeric micelles and micelles built around a solid core) able to carry, simultaneously, a drug and a contrast agent and externally modified with targeting peptides are described.

Rubber-filler systems have been widely used in industry. Fillers are not dispersed homogeneously and often form hierarchical structures in rubber matrices over a wide range of length scale from nanometer to micron meters, such as primary particles, aggregates and agglomerates. The combined scattering methods are powerful tools to characterize the structures quantitatively.

A method is described that can predict the miscibility of the great majority of polyolefins based just on their chemical architecture. The miscibility of polyolefins is shown to be essentially controlled by their solubility parameters, d, which in turn depend on the chain dimensions of the chains through the packing length l_p. A method to estimate l_p from chain architecture is also shown, giving a very powerful mechanism to predict the mixing thermodynamics from chemical structure.

Grazing incidence small-angle neutron scattering (GISANS) allows for the investigation of nanostructures in thin films and at surfaces due to the use of a reflection geometry. Possibilities and challenges of GISANS are reviewed with several different examples of thin nanostructured polymer films. With GISANS buried lateral structures can be probed destruction free using the variable-probed depth as function of the incidence angle. By this, averaged statistical information is detected over the large illuminated sample surface.

Various properties of ultrathin polymer films differ substantially from their bulk values. However, the critical question is whether the unusual properties are uniform throughout the films. To explore the presence of heterogeneous viscosity distributions, we have established grazing-incidence X-ray photon correlation spectroscopy for single polymer films with embedded metal nanoparticles that act as markers. In addition, the combined use of resonance enhanced X-ray scattering enables us to intensify the probing electrical field in the regions of interest within a single polymer film.

With the increase in the number of implant-dependent surgeries and biofilm-associated complications, there is a need to counteract and deal with this phenomenon. This has led to various approaches to elucidate the etiology and pathogenesis of the infection. This review critically evaluates the formation, characteristics, pathogenicity and the molecular genetics of both implant- and nonimplant-associated medical biofilm.

Studies on NMR methodology of characterizing the structure of polymers and biopolymers based on understanding of NMR chemical shift/structure correlation by solution-state and solid-state NMR experiments, development of NMR chemical shift theory and their combination have been reviewed.

Various types of dendrimer-based nanomaterials, such as poly(ethylene glycol)-modified dendrimers, functional shell-bearing dendrimers, thermosensitive dendrimers, dendron-based lipid assemblies and dendrimer-gold nanoparticle (NP) hybrids were developed by surface modification, assembling and hybrid formation strategies. These dendrimers and dendrimer-based nanomaterials exhibited various bio-related functions, such as drug encapsulation, stimuli-responsive transition and photo-induced heat generation. Based on these functions, these dendrimers and dendrimer-based nanomaterials have potential usefulness in the biomedical field, such as target-specific drug delivery and non-invasive therapy.

Dendrimers have attracting great interests in the design of functional materials. Because the core porphyrin unit in dendrimer porphyrin (DP) is surrounded by large poly(benzyl ether) dendritic wedges with ionic periphery, various functional nano-devices, such as DP-loaded polyion complex micelles, ternary complex system for gene delivery, polymer-metal complex micelle, hollow nanocapsules for combination cancer therapy, DP-immobilized surface for diagnostic tools, have been designed through electrostatic interaction with oppositely charged polymeric materials.

For high-performance boron neutron capture therapy , core-shell-type biodegradable nanoparticle-containing boron cluster is designed in order to improve accumulation tendency to tumor. Copolymerization of styrene carrying carborane with poly(ethylene glycol)-block-poly(lactide) (PEG-b-PLA-MA), possessing a methacryloyl group at the PLA end is performed. The accumulation of the polymerized micelles in tumor is much higher than that of the non-polymerized micelles because of the enhancement of the stability of the micelles. Thermal neutron irradiation exhibits significant suppression of tumor growth in the mice treated with the polymerized micelles.

This paper reviews the synthetic strategies for HBPs with controlled DB by specially designing monomer architectures. Several research groups including our group have been overcoming the statistical determination of DB in a random polymerization by tuning the rate constant of the first substitution reactions (k₁) and that of the second reaction (k₂) of an AB₂ monomers. As a result, HBPs with 100% DB, linear polymers (0% DB) and HBPs with any percentage of DB have been successfully synthesized.

Protein adsorption on the poly(ethylene glycol) (PEG)-tethered-chain surface was almost completely suppressed by successive treatment of longer PEG chain followed by treatment of PEG (2 kDa; mixed-PEG tethered-chain surface) because of significant increase in PEG chain density. Using pentaethylenehexamine-ended PEG, which was newly designed by ourselves, antibody/PEG and oligoDNA/PEG co-immobilizations were carried out. The PEG tethered chain was found to work not only as a non-fouling character but also as an improvement in orientation of biomolecules. Thus, it is promising as a high-performance biointerface for versatile applications.

Slide-ring gel with freely movable crosslinks shows extremely small Young's modulus and recovers the deformed shape to the original one instantaneously and completely. The small modulus arises from new entropic elasticity because of the heterogenous distribution of free cyclic molecules on polyrotaxane. The sliding elasticity appears in the sliding state, where axis polymer chains and cyclic molecules are sliding actively. In addition, the slide-ring gel should show the sliding transition between the rubber and sliding states. These aspects indicate that the slide-ring gel has its unique dynamics in mechanical properties.

Poly[2]rotaxane and graft polyrotaxane were synthesized from a mixture of poly(crown ether) as a trunk polymer, boronic-acid-terminated secondary ammonium salt as an axle component and diol as an end-capping group by pseudorotaxane formation and subsequent catalyst-free dehydrative bondage between the boronic acid and the diol moieties. It turned out that the chemical stability of these supramolecular architectures primarily depends on the bulkiness of the diol group as the end-capping moiety and the inherence originating from the dynamic covalent bond of boronate.

To obtain a novel biomimetic polymer, we have been studying polymers with an autonomous self-oscillating function. We succeeded in developing a novel self-oscillating polymer and gel by using an oscillating reaction, called the Belousov–Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. Several kinds of functional material systems using the self-oscillating polymer and gel, such as biomimetic actuators, mass transport surface and so on, are expected.

The recent remarkable progress in structural investigations of helical polymers by high-resolution atomic force microscopy provides their exact helical structures including helical pitch and handedness. Seeing is believing!