Izuru Kawamura

A single stereochemical inversion at the central residue of Val–Val–Ile tripeptides controls molecular packing and self-assembly pathways, producing distinct supramolecular organizations across multiple length scales.

Ultrafast 160 kHz magic-angle spinning substantially improves spectral resolution in ¹ H-detected solid-state NMR of a fully protonated seven-transmembrane protein embedded in lipid bilayers while maintaining its native-like structure.

The dynamic interfacial adsorption behavior of cellulose nanofibers (CNF) in Pickering emulsions (PE) remains poorly understood at the molecular scale. Here, we present a fluorescence-grafted CNF strategy to directly visualize and analyze these processes. Oil-in-water PE are prepared using acridon-2-yl-alanine-grafted TEMPO-oxidized CNF (Acd-CNF) and Nile Red-stained dodecane as the oil phase. This system retains aqueous dispersibility and enables the detection of molecular proximity between the two fluorophores as an interfacial fluorescence response. Time-lapse confocal laser scanning microscopy reveals that the slowly introduced Acd-CNF dispersions spontaneously adsorb onto preformed TEMPO-oxidized, CNF-stabilized PE, leading to the formation of heterogeneous and multilayered interfacial architectures rather than a uniform monolayer. These findings indicate that CNF adsorption at oil–water interfaces proceeds through dynamic and hierarchical processes, challenging simplified static models of PE stabilization. Extension of this approach provides a new experimental framework for the rational design of PE and interface-engineered soft materials.

The flower industry generates substantial amounts of stem and leaf waste from non-standard or unsold flowers, which are often discarded as waste despite their potential as a renewable biomass resource. In this study, we investigated the upcycling of flower stem and leaf powder into cellulose nanofibers (CNFs) using two distinct isolation methods: TEMPO-mediated oxidation to produce TEMPO-oxidized CNFs (TCNFs) and mechanical disintegration to produce mechanically disintegrated CNFs (MCNFs). The morphology of the obtained nanofibers was examined using atomic force microscopy and field-emission scanning electron microscopy, revealing that TCNFs exhibited thinner, more uniform fibrils with higher aspect ratios, whereas MCNFs displayed slightly thicker fibers with greater heterogeneity. Rheological measurements indicated shear-thinning and thixotropic behavior for both CNF suspensions, with viscosity primarily dependent on the concentration rather than the disintegration method. Solid-state nuclear magnetic resonance (NMR) and Fourier transform infrared analyses confirmed the removal of hemicellulose and lignin in both samples, while TCNFs exhibited a characteristic peak for carboxyl groups at 175 ppm and 1605 cm^-1, reflecting TEMPO oxidation. NMR analysis revealed no significant differences between the crystallinity indices of the two CNF samples. These findings demonstrate that flower stems and leaves-an underutilized form of floral waste-can be effectively converted into CNFs with distinct structural and chemical characteristics, depending on the isolation strategy. This study highlights the potential of floral waste valorization as a sustainable technique to obtain nanocellulose for high-value applications.

Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH₂ (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position in N(dW)F influences its conformation and biological characteristics. We demonstrated the chiral separation of N(dW)F and its diastereomer NWF using (S)-3,3′-diphenyl-1,1′-binaphthyl-20-crown-6-ether columns (CR-I(+)). A reduction in the ratio of acetonitrile and methanol in the mobile phase allowed the complete separation of N(dW)F and its diastereomer, improving the separation factor (α) from 0.96 to 6.28. Molecular dynamics simulations revealed that the interaction of N(dW)F with CR-I(−) was more favorable than with CR-I(+). These findings indicate that the structure of the CR-I column stereoselectively recognizes peptides and facilitates the separation of naturally occurring D-amino acid residue-containing tripeptides.