Oxygen absorber is subsidiary packaging material which can prevent the deterioration of foods caused by oxidizing and molding. Oxygen absorber is principally classified into two groups according to material; inorganic type or organic type. It is reported that one of the organic oxygen absorber is fabricated from the mineral carrier impregnated with glycerol and alkaline agent.

In this study, core-shell organic oxygen absorber was fabricated by one pot process using mixing agitator. In the first step, core particles containing glycerol for oxygen-absorbing materials were obtained by agitation granulation method. In the next step, shell layer was formed on the core particle by coating of hydrophilic silica. Quantitative analysis of shell layer by cross-sectional energy dispersive X-ray spectroscopy (EDX) indicated that oxygen-absorbing materials migrated from core to silica shell layer which has high surface areas, resulting in the improvement of oxygen absorbing performance.

In the field of non-equilibrium science, the Liesegang phenomenon is well-known as a particle formation process involving the diffusion of precursor chemicals. From a chemical engineering perspective, our research group had previously applied this method to synthesize metal nanoparticles and found that when Au ions diffuse unidirectionally into a gel containing a reductant, bands of Au nanoparticles are formed in a striped pattern. However, metal species other than Au have not yet been investigated. In this study, we synthesized nanoparticles of other metal species (Pt and Pd) using a similar process and compared the results with those of the Au nanoparticles to clarify the particle formation mechanism. The findings showed that the band patterns that were formed vary according to the metal species. Furthermore, the bands formed in each metal species were reproduced by using a mathematical model capable of representing the diffusion of ions and the formation of particles.

We successfully developed a new type of porous structured particles via self-assembly of TEMPO-oxidized cellulose nanofibers (TOCNF) and magnetic nanoparticles (Fe₃O₄) as building blocks by spray-drying process. The TOCNF/Fe₃O₄ composite porous particles possessed unique macro–meso–microporous structures with a high surface area (15 m²/g) and a highly negative charge (ζ potential = −55 mV). The Fe₃O₄ nanoparticles played an important role in increasing the specific surface area by inhibiting aggregation of the TOCNF. The TOCNF/Fe₃O₄ composite porous particles allowed excellent mass transfer of lysozyme, which led to high adsorption capacities of > 950 mg/g, rapid equilibrium.

Supramolecular chemistry has attracted a wide range of attention because of unique and fascinating characteristics in nanoscale structures and functional properties since the end of the last century. A supramolecular gel is a typical example of supramolecular chemistry. Peptide amphiphiles, which are designed to have hydrophobic/hydrophilic balances, are representatives of a supramolecular gelator (often called low-molecular-weight gelator, LMWG). Since the molecular weight of a LMWG is relatively small, a precise molecular design allows the programmed self-assembly, which leads to form wormlike micelles (nanofibers) in response to a variety of designated stimuli at the designated time. Several groups including our group reported the formation of nanostructures based on the LMWGs inside living cells, leading to the death of animal and bacterial cells. This article describes our studies on the LMWGs that self-assemble inside living cells in response to cell-related stimuli, leading to selective cell death. The self-assembly of synthetic molecules inside living cells has a high potential for a mode of therapy, disinfection or a novel cell-removal tool.

Microfluidics is a powerful tool to precisely control the structure of colloidal materials. A microfluidic process to fabricate monodisperse hydrogel microcapsules having a large aqueous core using phase separation in aqueous droplets was developed. Specifically, hydrogel microcapsules were prepared by the formation of aqueous two-phase system droplets with dextran-rich core and tetra-PEG-rich shell, and subsequent cross-linking reaction in the shell. This process enabled to produce hydrogel microcapsules in the absence of radical initiators and external energies such as heat and ultraviolet light. The diameter and shell thickness of the microcapsules could be modulated independently by changing flow rates and monomer concentrations upon droplet formation. In addition, tuning the rate of polymerization was found to be an important parameter to determine the phase-separated structure of the hydrogel particles. In this review, the experimental procedures and the representative results are reported and key points to produce well-defined hydrogel materials are discussed.