Volume 53 Issue 12, December 2021

Boronic acids (BA) are known for their ability to reversibly interact with the diol groups, a common motif of biomolecules including sugars, ribose, and catechols. One can tailor BAs to elicit a divergent profile of binding strength and specificity on the basis of stereochemistry and controlled electronic effects. This focus review provides an overview of a phenylboronic acid (PBA)-based, totally synthetic platform for insulin delivery applications developed in our group, with focuses on the development of new PBA derivatives, glucose-responsive gels, and the gel-combined medical devices.

Water-gated polymer thin-film transistors (WG-PTFTs) fabricated by a simple procedure can be operated at an ultralow voltage, whereby the WG-PTFTs with molecular recognition units allow chemical sensing. Upon the addition of analytes, the electric double layer capacitance of the WG-PTFTs can be changed by accumulation and desorption of charged species at the interface of the semiconductor and electrolytes. For example, the WG-PTFTs have successfully detected biogenic amines and a herbicide glyphosate. In short, our proposed WG-PTFTs are among the most promising platforms for sensing applications based on π-conjugated polymer materials.

The recent advances of the novel signal-amplification method, “supramolecular allosteric signal-amplification sensing” (SASS), are shown and summarized in this review. The SASS using polymers, polythiophenes and glucans introduced herein will be expandable to further smart polymeric systems, i.e., dynamic supramolecular assemblies.

The structural characterization of DDS carriers, including transdermal DDS, is one of the essential factors in the understanding of the biological properties and useful for the development of new carriers. This review introduces a quantitative evaluation of the surface coating on a carrier with the contrast variation technique of SAXS in the first section and the localization determination of drug molecules in liposomes in the second section. The final section describes the microemulsions containing deep eutectic solvents in the inner phase for use in transdermal DDS.

Silk fibroin (SF) is a natural protein polymer material and has been fabricated and studied as a scaffold for tissue engineering and regenerative medicine. To append new functions to SF scaffolds and understand their in vivo behaviors, researchers have addressed modifications of SF scaffolds by using transgenic silkworm and peptide modification technologies. These modified SF scaffolds had on-target functions and showed their potential as a material for tissue engineering applications. This review summarizes the methodologies and characteristics of functionalized SF scaffolds.

Acidic pH is identified for various types of tumors, whereby it can be employed for crafting tumor-targeted nanomaterials. Cationic net charge of the nanomaterials at tumorous pH achieves selective interaction with anionic tissue constituents at tumor sites, for the effective tumor accumulation. However, tumorous pH is ca. 6.5, whereas pH of normal tissues is 7.4, and therefore responsiveness to the small pH window is the key toward the success for tumor delivery. The present manuscript highlights the polymer designs that recognize tumorous pH to make tumor-targeted nanomaterials.

Diblock copolymers consisting of flexible polystyrene and semiflexible poly(n-hexyl isocyanate), P(S-b-HIC)s, were prepared by anionic polymerization, followed by SEC fractionation. The microphase-separated structures of two P(S-b-HIC)s with Φ_PHIC = 0.18 and 0.31, were investigated by TEM, SAXS and WAXS. Both two P(S-b-HIC)s exhibited hexagonally packed cylindrical structures but different cross-sectional shapes, namely, P(S-b-HIC)-0.18 has a round-shaped cross-section, while P(S-b-HIC)-0.31 has a distorted one. The latter could originate from the liquid crystalline structures of the PHIC blocks in cylindrical domains, which align obliquely to the interface of the domains.

A mesh-like crystal structure of ultrahigh molecular weight polyethylene (UHMWPE) films is achieved through a two-step biaxial stretching mode to construct a planar-oriented crystal network. This mesh-like crystal network structure was investigated through scanning electron microscopy (SEM) and 1-dimensional wide-angle X-ray diffraction (1D-WXRD). The corresponding in-plane thermal conductivity increases to 7.3 W.m/K at a total draw ratio of 25, much higher than samples with single temperature biaxial stretching modes.

A transparent film with photoactive antiviral functions and minimal degradation over time was easily obtained by uniformly dispersing the phenoxy-substituted phthalocyanine zinc (PPcZn) in the cellulose acetate film. This film produced singlet oxygen (¹O₂) upon visible light irradiation, and the production capacity of ¹O₂ was maintained even when the film was exposed to indoor lighting for 6 months.

In this work, we employed Carbothane® electrospun matrices (PCU) for lysine surface modification, using oligomers obtained from allyl glycidyl ether (AGE) reaction as spacers. The incorporation of AGE oligomers significantly reduced the nonspecific protein adsorption, while further modification with lysine led to a more pronounced decrease. The lysine-modified matrices presented increased plasminogen adsorption capacity and in vitro clot lysis ability, confirming the plasminogen adsorption selectivity and thus improving the hemocompatibility behavior of these matrices.

Proton exchange membranes (PEMs) based on trifluoromethanesulfonylimide-grafted polybenzimidazole (PBI-TFSI) were prepared, and their physical and chemical properties were studied. PBI-TFSI showed higher proton conductivity than Nafion and propanesulfonic acid-grafted polybenzimidazole (PBI-PS) at a 40% relative humidity due to its high acidity of side chain. PBI-TFSI membranes are promising materials for next-generation PEM fuel cells.

The self-assembly process of a lysine derivative (Fmoc-Lys) in water-DMSO mixtures was investigated by time-resolved static and dynamic light scattering, small-angle X-ray scattering, optical microscopy, and scanning electron microscopy. The experimental results indicated liquid-liquid phase separation caused by the addition of water to the DMSO solution of Fmoc-Lys and the formation of spherical droplets of the phase-separating concentrated phase. In the colloidal phase-separating solution, the concentrated phase droplets did not grow through the Ostwald ripening process, but transformed to a crystal phase after a long lag phase.

Three different silk sources were explore for sericin (SS) extraction and film formation. Features of each raw material, especially the degree of processing, have remarkable effects on the primary structure and the presence of nonprotein compounds in the sericin extract. As a result, sericin films exhibited distinctive properties that seemed to be correlated with the amount of natural impurities and the molecular properties of the SS extract obtained from each raw material.

Simulation-based materials informatics shows that when the detachment energies of the odd-numbered amino acids with –COOCH₃ are high, and when the detachment energies of the even-numbered amino acids with –CH₃ are high, the binding free energy between the peptide and PMMA resin becomes high. From this guideline, W, R, and E are found to be effective as odd-numbered amino acids, and W and R are found to be effective as even-numbered amino acids for strong adhesion to PMMA resin.

Polyhydroxyalkanoate copolymers of (2R,3R)-3-hydroxy-2-methylbutyrate and (R)-3-hydroxybutyrate [P(3H2MB-co-3HB)] with various comonomer compositions were biosynthesized using recombinant Escherichia coli. Furthermore, solvent fractionation of P(3H2MB-co-3HB) was performed to obtain copolymers with narrow comonomer-unit compositional distributions. The melting temperature (T_m) of P(3H2MB-co-3HB) as a function of the comonomer content indicated isodimorphism of the copolymer. The fast crystallization behavior of P(3H2MB) was maintained even when it was copolymerized with 3HB. The P(80 mol% 3H2MB-co-3HB) copolymer, with a T_m close to that of P(3HB), exhibited faster crystallization behavior than the P(3HB) homopolymer.

To improve the 3-dimensional (3D) printed quality of bio-based composites, bamboo fibers were chemically modified via a two-step reaction. In the first step, NCO groups (of a diisocyanate) were grafted onto the surface of fibers, which were subsequently reacted with a polyol. Afterward, 3D-printed objects were produced using these fibers. The advantage of using treated fibers was reflected in the improved mechanical performance of the obtained 3D specimens.

Composites of fluoropolymer (FKM) and nano-carbon fillers have been considered as sealing materials for hydrogen fuel storage. We here characterize, structurally and dynamically, FKM chains adsorbed on single-walled carbon nanotubes (SWCNTs) and carbon black (CB), which were prepared by a solvent leaching method.

An optically active acylhydrazine-functionalized biphenyl (AHB) carrying L-alanine-derived oligoamide side chains supramolecularly coassembled with the corresponding achiral AHB to form a one-dimensional helical nanofiber, in which intermolecular hydrogen bonding between the chiral/achiral oligoamide pendant units resulted in modest chiral amplification (the sergeants-and-soldiers effect). The chiral/achiral AHB-based covalent copolymers folded into a preferred-handed helical structure with amplification of the helical sense excess driven by intramolecular hydrogen bonds and further polymerized into a higher molar mass supramolecular helical polymer stabilized by end-to-end intermolecular hydrogen bonding.

Time-resolved small-angle X-ray scattering measurements were made for a mixed solution of silica nanoparticles (SiNPs) and atelocollagen (AC) in aqueous media. The scattering intensity from the SiNPs gradually changed and reached asymptotic values approximately 5–20 min after rapid mixing of the two solutions. The obtained time scale to form the complex can be important information to control the aggregating structure of SiNPs with the aid of collagen molecules.

We prepared monolayer- and bilayer-type AuNP-containing collagen coatings as a photosensitive cell scaffold in a photoinduced in situ cell detachment system. The monolayer type of AuNP/collagen coatings showed efficient cell detachment with cell damage and may be applied to remove undesired cells. The bilayer-type AuNP/collagen coatings may be applied to collect desired cells because of the low cell damage. We demonstrated the sorting of visually changed transfected CHO-K1 cells and human-induced pluripotent stem cell-derived cardiomyocytes using our system, which is useful for genome editing and regenerative medicine, respectively.

We developed lanoconazole (LCZ)-loaded emulsions stabilized with cellulose nanocrystals grafted with polyphosphoesters (LCZ-loaded CP-PEs). The sustained release of LCZ and superior skin permeation of the LCZ-loaded CP-PEs, likely due to the excellent stability and rigidity of oil droplets, assured prolonged local action. The anti-inflammatory efficacy of the LCZ-loaded CP-PEs was confirmed using a mouse ear model of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation.