MDPI Acta Medica Okayama 2076-3417 14 23 2024 Preparation of Nano- and Microparticles Obtained from Polymerization Reaction and Their Application to Surface Coating of Woody Materials 11326 EN Toshinori Shimanouchi Department of Environmental Chemistry and Materials, Okayama University, Daichi Hirota Department of Environmental Chemistry and Materials, Okayama University, Masafumi Yoshida Department of Environmental Chemistry and Materials, Okayama University, Kazuma Yasuhara Division of Materials Science, Nara Institute of Science and Technology (NAIST) Yukitaka Kimura Department of Environmental Chemistry and Materials, Okayama University, A surface coating of polymer particles of different hydrophobicity and wide-ranged size is helpful for the surface modification of materials such as woody thin board (WTB) derived from biomass. A preparation method for polymer particles was, in this study, proposed using a capillary-type flow system. Under hydrothermal conditions, the refinement of dispersed oil droplets in water (O/W emulsions) and the polymerization reaction could be simultaneously advanced, and polymer particles of polystyrene (PS), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), and poly-L-lactic acid (PLLA) with a particle size of about 100 nm could be synthesized. The coating of polymer particles gave an improved effect on the water repellency of WTBs due to the hydrophobicity of polymer particles and an alteration of surface roughness, and it also provided long-term stability (more than 6 years). No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2076-3417 11 10 2021 Fibril Growth Behavior of Amyloid beta on Polymer-Based Planar Membranes: Implications for the Entanglement and Hydration of Polymers 4408 EN Toshinori Shimanouchi Graduate School of Environment and Life Science, Okayama University Miki Iwamura Graduate School of Environment and Life Science, Okayama University Shintaro Deguchi Graduate School of Environment and Life Science, Okayama University Yukitaka Kimura Graduate School of Environment and Life Science, Okayama University The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid beta peptide (A beta) would contribute to the inhibition of fibril growth causing Alzheimer's disease. We systematically studied the amyloidogenicity of A beta on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of A beta fibril formation. Rates of A beta nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. A beta accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer-A beta entanglement might contribute to the accumulation of A beta and subsequent fibrillation. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 0927-7757 520 2017 Indocyanine green-laden poly(ethylene glycol)-block-polylactide (PEG-b-PLA) nanocapsules incorporating reverse micelles: Effects of PEG-b-PLA composition on the nanocapsule diameter and encapsulation efficiency 764 770 EN Takaichi Watanabe Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Yui Sakamoto Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Tetsuya Inooka Division of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Yukitaka Kimura Division of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Tsutomu Ono Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Reverse micelles are thermodynamically stable systems, with a capacity to encapsulate hydrophilic molecules in their nanosized core, which is smaller than the core generally obtained with water-in-oil-emulsion droplets. Herein, we present a simple technique for the preparation of poly(ethylene glycol)-block-polylactide (PEG-b-PLA) nanocapsules encapsulating a hydrophilic photosensitizer (indocyanine green, ICG), which exploits reverse micelle formation and subsequent emulsion-solvent diffusion. We establish the effect of the PEG-b-PLA composition and the co-surfactant volume on the diameter and water content of the reverse micelles. We demonstrate that the composition of PEG-b-PLA affects also the diameter and encapsulation efficiency of the resulting nanocapsules. We show that the ICG-laden nanocapsules fabricated under the most optimal conditions have a diameter of approximately 100 nm and an ICG encapsulation efficiency of 58%. We believe that the method proposed here is a promising step towards the preparation of hydrophilic drug-laden polymer nanocapsules with a small diameter and therefore suitable for use in drug delivery applications based on enhanced permeability and retention (EPR) effect-driven passive targeting. No potential conflict of interest relevant to this article was reported.

Royal Society of Chemistry Acta Medica Okayama 2046-2069 4 10 2013 Monodisperse polylactide microcapsules with a single aqueous core prepared via spontaneous emulsification and solvent diffusion 4872 4877 EN Takaichi Watanabe Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University Yukitaka Kimura Department of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Tsutomu Ono Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University A simple approach to preparing monodisperse poly(D,L-lactide) (PDLLA) microcapsules with a single aqueous core is developed. The method is based on automatic water-in-oil-in-water double emulsion formation from oil-in-water single emulsion via spontaneous emulsification which voluntarily disperses part of continuous aqueous phase into the dispersed oil phase dissolving oil-soluble amphiphilic diblock copolymer, poly(D,L-lactide)-b-poly(2-dimethylaminoethyl methacylate)(PDLLA-b-PDMAEMA), followed by coalescence of tiny water droplets within the polymer droplets, coupled with quick precipitation of polymers by diluting the emulsion with water. In this study, we have investigated the effect of PDLLA to PDLLA-b-PDMAEMA ratios and flow rates of each solution during preparing the emulsion on the final morphology and the size of the microcapsules. It was found that the polymer blend ratio played a crucial role in determining internal structure of the microcapsules. The microcapsules size decreased with the increment of the flow rate ratios of the continuous phase to the dispersed phase and eventually reached 10 μm, while maintaining narrow size distribution. In addition, we have demonstrated that the microcapsules can encapsulate both hydrophilic and hydrophobic compounds during the formation. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 0743-7463 29 46 2013 Microfluidic Fabrication of Monodisperse Polylactide Microcapsules with Tunable Structures through Rapid Precipitation 14082 14088 EN Takaichi Watanabe Department of Chemistry and Biotechnology, Graduate School of Natural Science and Technolog Yukitaka Kimura Department of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University Tsutomu Ono Department of Chemistry and Biotechnology, Graduate School of Natural Science and Technology We describe a versatile and facile route to the continuous production of monodisperse polylactide (PLA) microcapsules with controllable structures. With the combination of microfluidic emulsification, solvent diffusion, and internal phase separation, uniform PLA microcapsules with a perfluorooctyl bromide (PFOB) core were successfully obtained by simply diluting monodisperse ethyl acetate (EA)-in-water emulsion with pure water. Rapid extraction of EA from the droplets into the aqueous phase enabled the solidification of the polymer droplets in a nonequilibrium state during internal phase separation between a concentrated PLA/EA phase and a PFOB phase. Higher-molecular-weight PLA generated structural complexity of the microcapsules, yielding core–shell microcapsules with covered with small PFOB droplets. Removal of the PFOB via freeze drying gave hollow microcapsules with dimpled surfaces. The core–shell ratios and the diameter of these microcapsules could be finely tuned by just adjusting the concentration of PFOB and flow rates on emulsification, respectively. These biocompatible microcapsules with controllable size and structures are potentially applicable in biomedical fields such as drug delivery carriers of many functional molecules. No potential conflict of interest relevant to this article was reported.

Royal Society of Chemistry Acta Medica Okayama 1744-683X 7 21 2011 Continuous fabrication of monodisperse polylactide microspheres by droplet-to-particle technology using microfluidic emulsification and emulsion–solvent diffusion 9894 9897 EN Takaichi Watanabe Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University Tsutomu Ono Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University Yukitaka Kimura Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University Monodisperse polylactide (PLA) microspheres were continuously fabricated by microfluidic emulsification and subsequent dilution in water. The diameter was precisely tuned from 6 to 50 μm by changing the flow rate of the fluids in microfluidics or the PLA concentration in the dispersed phase. The use of amphiphilic oil-soluble poly(ethylene glycol)-b-polylactide (o-PEG–PLA) as a matrix resulted in a highly porous microsphere morphology, and the porosity was controlled by blending PLA. Therefore, monodisperse PLA microspheres with the predetermined surface porosity were continuously produced by just enough reagents and energy. No potential conflict of interest relevant to this article was reported.