Reviews & Analysis

Dispersibility and interfacial interactions are the important factors to exploit the high potential of nanocarbons for polymer/nanocarbon nanocomposites. However, carbon backbone with low reactivity has often cause agglomerations and defects from the interfaces. The use of surfactants and the surface modifications of nanocarbons have widely been conducted to improve these issues. This paper reviews recent advances in the design of polymer/nanocarbon nanocomposites, focusing on our research on the reinforcement effect of nanodiamond on polymer nanocomposites.

Sacrificial bonds break to dissipate energy and can increase the toughness of materials. Incorporating sacrificial bonds into hydrogels through the double network process enabled the first extremely tough hydrogels. In this Focus Review, we discuss the nature of sacrificial bonds, and how they can be used on the macroscale to enable tough soft composite materials. By matching the essence of the double network concept, we can make tough materials from macroscale composites for biomedical and engineering applications.

In 1996, the author reported “self-oscillating” polymer gels that spontaneously repeat swelling–deswelling changes in a closed solution without any on–off switching by external stimuli, such as with heart muscle. The gel has an energy converting system provided by an oscillatory chemical reaction called the Belousov–Zhabotinsky (BZ) reaction, which induces periodic mechanical motion of the polymer chain. The author systematically developed self-oscillating polymer gels with approaches ranging from demonstrating fundamental behaviors to constructing material systems for potential applications in biomimetic materials such as autonomous soft actuators, automatic transport systems, and functional fluids causing autonomous sol-gel oscillations, as seen with amebas. In this review, these research developments and recent progress from the author’s group are summarized.

This focus review describes a biosensing strategy called “chemical tongue”, which mimics the human taste system by employing fluorogenic materials containing various chemical structures in conjunction with statistical techniques. The focus is on the design of polymer-based chemical tongues and their applications with various complex biological samples. The chemical-tongue strategy is capable of recognizing biological samples in a unique manner that does not, in contrast to conventional approaches, rely on specific interactions, thereby potentially opening avenues for unexplored uses of polymers in a wide range of research areas.

Reverse osmosis (RO) membranes are widely used as energy-saving and environmentally friendly materials for water purification. This Focus Review reports on the nanoscale structure and permeation mechanism of crosslinked fully aromatic polyamide RO membranes. First, the research on the morphology of protuberance structures of the polyamide separation functional layer is described. Next, hydrated structure of the functional layer is focused, which was analyzed using neutron scattering and molecular dynamics simulations. Innovative RO membranes are being developed that can obtain higher quality water with less energy by precisely controlling nanostructures.

In this review, we overview the recent advances associated with seminal findings in the development of nucleic acid-based fluorescent sensor systems aimed at application for exploring intracellular phenomena. We described the fluorescence signal generation mechanisms of each nucleic acid-based fluorescent sensor, including molecular beacon and quencher-free linear probes, as well as aptamer or DNAzyme-based systems. In addition, cascade hybridization chain reaction and catalyzed hairpin assembly are introduced as methods for amplifying fluorescence signals under isothermal conditions.

Bacterial cellulose (BC) has been utilized as a biopolymer matrix for various applications. The advancement of synthetic biology has brought new approaches for its production and functionalization. In this mini-review, we briefly discuss the conventional methods employed to improve BC production and functionalization as well as their challenges. We summarize the applications of synthetic biology to address the challenges and its use to develop novel hybrid living materials. Finally, we consider the opportunities and future prospects of synthetic biology and engineered biological materials.

Polysaccharides and “imogolite” (a natural aluminum silicate nanoclay) were used as building blocks to prepare environmentally benign (organic/inorganic) hybrid materials of natural origin. Cellulose nanocrystals (CNCs), cellulose fibers (CFs), and sacran were employed as polysaccharides. By utilizing oppositely charged organic and inorganic components, polysaccharide/imogolite hybrids were prepared by spin-assisted layer-by-layer assembly and solution blending. The fine dispersion and attractive interactions of imogolite with polysaccharides afforded hybrids with improved physicochemical properties.

The self-assembly of carbohydrate-based block copolymer systems has allowed recently the conception of novel glyconanoparticles and high-resolution patterning thin films with sub_10nm resolution (high χ) that has never been attained by petroleum-based copolymers and provides these new nanostructured biomaterials with novel properties such as next generation nanolithography, memory devices, OPV and biosensors. The glyconanoparticles can be designed to meet the targeted applications in terms of size, encapsulation and decoration. The control of the lamellar/cylindrical phases orientation can be achieved using thermal, solvent vapor or microwave annealing processes in thin films.

Random pH-responsive copolymers, P(A/AaU) have been prepared from a pH-responsive pendant fatty acid-containing monomer (AaU) and a pendant sulfonate-containing monomer (AMPS). In water, P(A/AaU) formed unimer micelles under acidic conditions. Under basic conditions, the P(A/AaU) polymer chains expand due to the electrostatic repulsions. Although pH-responsive sunscreen shows waterproof properties under neutral conditions, it disperses under weakly basic conditions such as soap water. pH-responsive diblock copolymers with a pendant fatty acid-containing block were prepared. This review also discusses pH-responsive gelling agents based on ABA triblock copolymers.

Research advances in the extraction, structural and conformational characteristics, and biological activities (antitumor, anti-inflammation, immunomodulatory, hypoglycemic activity) of β-glucans from three fungi, Auricularia auricula judae, Lentinus edodes and yeast, as typical representatives, were reviewed, as well as the potential mechanism and the structure-function relationship. Additionally, as-fabricated β-glucan-derived nanocomposite biomaterials as carriers for delivering drugs, genes, nanoparticles, and fluorescence probes were addressed.

The present review focuses on the enzymatic synthesis of unnatural oligosaccharides and polysaccharides linked through strictly controlled α(1→4)-glycosidic linkages by glucan phosphorylase (GP) catalysis. In particular, the recent progress of the enzymatic synthesis of unnatural polysaccharides by GP (isolated from thermophilic bacteria, Aquifex aeolicus VF5)-catalyzed polymerization and related reactions is overviewed. The unnatural substrates have high applicability as practical functional materials in pharmaceutical, medicinal, and biological research fields.