Focus Review

Thermal and mechanical properties of PMMA were modified through lithium-salt doping, which induces ion–dipole interactions with carbonyl groups. Localized water spots are formed around the ions of the hygroscopic salts in PMMA, and their strain-driven redistribution governs the humidity-responsive ductility. This review integrates these findings with a nonequilibrium constitutive model that captures water migration during deformation, providing a framework for designing PMMA with tunable properties.

Hydration water can be classified into three types: free water, intermediate water, and nonfreezing water. Intermediate water was found in hydrated biopolymers and hydrated biocompatible synthetic polymers. ATR-IR spectroscopy combined with machine learning revealed the power of spectroscopic approaches to link molecular-level hydration to macroscopic polymer properties. Long-range, intermediate water-mediated repulsive forces prevent protein adsorption, platelet adhesion, and overall biocompatibility under physiological conditions. This intermediate water barrier model provides a unified framework for designing biocompatible polymers.

Self-organized structures that emerge on gel surfaces across diverse spatiotemporal scales. This review introduces classical studies on these structures and further discusses recent advances and future perspectives.

Dendrimers are synthetic polymers with well-defined structures and are useful as drug carriers as well as smart materials. Recently, anionic-terminal phenylalanine (Phe)-modified polyamidoamine (PAMAM) dendrimers were synthesized. These dendrimers exhibited unique pH- and temperature-responsive properties, which were controlled by the dendrimer structure. These dendrimers also showed the ability to be delivered into lymph nodes and immune cells including T cells after the intradermal injection. This review focuses on their stimuli-responsive properties and applications in delivery systems for lymph node-resident immune cells.

This article reviews the design, synthesis, and properties of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers bearing phosphorylcholine groups, which mimic cell membrane surfaces to achieve biocompatibility and medical functionality. MPC polymer surfaces effectively suppress protein adsorption, cell adhesion, activation, and subsequent biological reactions. The practical approaches for implementing MPC polymers in medical devices are also described. Utilizing the unique bioinspired properties of MPC polymers, these devices have demonstrated remarkable performance in clinical use, significantly contributing to an improvement in patients’ quality of life.

This Review highlights our development of highly efficient and selective palladium catalysts for direct arylation polymerization (DArP). P(2-MeOC₆H₄)₃ (L1) serves as a key supporting ligand that maintains reactive mononuclear Pd species. Coligands (TMEDA or XPhos) suppress side reactions and facilitate the activation of less reactive C–X bonds. Operating in polymer-solubilizing media (e.g., THF or toluene), these systems yield π-conjugated polymers with number-average molecular weights of up to 347,700 and cross-coupling selectivities of up to >99%; the resulting materials exhibit device-grade performance comparable to that of polymers prepared by conventional Stille coupling.

Artificial nanocelluloses are produced via the self-assembly of low-molecular-weight (LMW) cellulose in vitro and represent an emerging class of nanocelluloses developed over the past decade. Most artificial nanocelluloses reported to date are particulates. We have developed two types of nanostructured macroscopic materials through the self-assembly of LMW cellulose: nanoribbon network hydrogels and nanospiked microfibrous materials. This Focus Review summarizes our work along with related studies on these novel nanostructured cellulose materials.

The selective capture of heavy metal ions is a major challenge due to the need for materials with high affinity, selectivity, and capacity. Nature uses proteins to manage metal ions via specific structural motifs. This focus review summarizes recent advances in bioinspired and biosynthetic integrated strategies for the capture of heavy metal ions. The topics discussed include (1) the structural and thermodynamic features of metal-binding proteins, (2) synthetic polymers that mimic the biological functions of proteins, and (3) hybrid materials that integrate biological (macro)molecules with synthetic polymers.

Time-resolved small-angle X-ray scattering (TR-SAXS) is crucial for real-time monitoring of soft matter kinetics, offering nanometer-to-micrometer structural insights and revealing complex kinetic pathways and mechanisms. This review highlights its power in understanding block copolymer self-assembly kinetics in solution, covering micelle formation driven by non-covalent interactions, polyelectrolyte complex micelles via electrostatic interactions, and polymerization-induced self-assembly (PISA).

Structural and steric restrictions in polymer chains resulted in significant differences between cyclic polymers and their linear counterparts in the interfacial properties. The topological influences on the air–water interfacial activity and aggregation behavior of PEG and Pluronic surfactants were investigated. Silver nanoparticles adsorbed with cyclic PEG exhibited high dispersion stability under physiological and various conditions. This study successfully combined the biocompatibility of PEG with the antibacterial activity of silver nanoparticles. These results demonstrate that utilizing polymer topology can serve as a useful tool for designing new functional materials.

Harnessing the plasmonic properties of gold nanorods (AuNRs) requires proper control of their arrangement and assembly. However, although the assembly of AuNRs into ordered structures has been achieved, active control over them remains challenging. The author and colleagues have developed methods to control the arrangement and assembly of AuNRs based on complex formation via electrostatic interactions with DNA, a polymer with unique properties, structure and excellent functionality. This Focus Review presents our work on the arrangement and assembly of AuNRs by DNA.

In this study, we developed starch-based films with tunable disintegration and dissolution rates in freshwater and seawater. The modified starch was mixed with oxidized cellulose or a water-soluble polymer to produce transparent, homogeneous films. Hydrogen bonding stabilized the films in freshwater, while in seawater, the hydrogen bond crosslinks dissociated, causing the film to dissolve rapidly. This technology offers a strategic balance between water resistance in everyday environments and controlled disintegration in marine conditions, presenting a sustainable alternative to petrochemical plastics with potential applications across various industrial sectors.

This paper reviews the degradation of polyesters and polycarbonates, including degradable aliphatic polymers. Organic catalysts enable efficient degradation and recycling of these condensation polymers, promoting a circular economy and reduction of waste and CO₂ emissions. Although super engineering plastics are difficult to recycle, recent studies show organocatalysts can facilitate their depolymerization and monomer recovery. Advances in monomer synthesis and controlled ring-opening polymerization allow for functional, sustainable, and degradable polymers. Moreover, side-chain engineering in aliphatic polymers enables controlled degradation. Future work should emphasize greener synthesis and comprehensive analysis of degradation impacts.

Emerging from DNA/RNA nanoengineering, synthetic nucleic-acid liquid condensates, forming via phase separation of nanostructures, have attracted increasing attention as a powerful platform for synthetic biology and molecular computing. Base-sequence specificity allows for molecular encoding for their organization, functions, and droplet interactions. Authors overview key topics of these programmable droplets, from dynamics programmability to numerical modeling. Additionally, this review highlights cross-linker modules, which enable dynamic compartmentalization and division of droplets triggered by specific molecular input. These modules allow the condensate phase behavior to represent Boolean logic operation.

Simple coacervates formed from low-molecular-weight molecules offer unique dynamic features, including stimulus-responsive phase transitions and reversible assembly/disassembly. This Focus Review highlights molecular design strategies, from historical perspectives to recent advancements. The sophisticated design of coacervates provides new opportunities in protocell models, biosensing, and drug delivery systems.

This review highlights recent advances in engineering artificial enzyme condensates in vitro using charged polymers. Based on our recent findings, we describe strategies for designing condensates through interactions between polymers and enzymes or coenzymes. We then summarize enzyme activation mechanisms triggered by enzyme condensates, including size-dependent effects and conformational changes in enzymes. We also discuss potential applications and future directions, including multienzyme systems, integration with solid surfaces, and combination with rational enzyme design.

The process of spider silk assembly is a concerted, transitional process that combines liquid‒liquid phase separation (LLPS), liquid‒crystal (LC) and liquid‒solid phase separation (LSP), yielding fibers with outstanding mechanical properties. Spider silk proteins form micelle-like assemblies that undergo LLPS to form larger droplets, which are highly relevant for preorientation and permit intra- and intermolecular interactions, leading to a dimerized protein network and a nematic crystal phase of β-sheet-rich nanofibrils. The final solid fiber is drawn via LSP.

Ribonucleoprotein (RNP) granules are membraneless organelles formed through the condensation of RNA and proteins, which serve critical functions in diverse biological processes and disease contexts. Identifying their RNA composition is vital for understanding their molecular functions and mechanisms of formation, yet conventional approaches often fail to fully capture the complexity of these granules. This review highlights recent advances in transcriptome profiling of RNP granules using biochemical purification and proximity labeling, offering new insights into their molecular roles.

Carrier-free nano-prodrugs (NPDs) were developed for selective drug release in cancer cells using stimulus-responsive systems: esterases, reactive oxygen species (ROS), and glutathione (GSH). Esterase-activated NPDs showed hydrophobicity-dependent drug release through SN-38 modification. ROS-responsive NPDs with trimethyl lock groups demonstrated selective activation by intracellular H₂O₂. GSH-responsive dimeric SN-38 prodrugs exhibited enhanced antitumor effects with reduced side effects. These NPDs achieved high drug loading and excellent stimulus responsiveness without using carriers, providing a promising platform for safer and more effective cancer therapy.