Published papers

Several kinds of submicron-sized microspheres having environment-sensitive shells were prepared and the effect of shell structure on the properties of microspheres was studied. The shell was composed of crosslinked or hairy poly(N-isopropyl acrylamide) (PNIPAM) whose lower critical solution temperature was about 32 °C but depended on the architecture of the shell. The resposivity of the shell to the change in environmental condition was sluggish when the shell was crosslinked. The decrease in the crosslink density of the shell was slightly effective in sharpening the response. But even non-crosslinked, hairy PNIPAM shell did not exhibit discontinuous transition at the critical condition. The response of hairy PNIPAM shell to environmental change was drastically sharpened by incorporating a slight amount of acrylic acid (AAc) in the hair.

In our previous paper, we reported a DNA diagnosis system in which fully complementary DNA was selectively hybridized with a DNA immobilized on latex particles but one-point mutant DNA was not. The system, however, included a few disadvantages. To overcome them, a single-strand DNA cleaving enzyme (S1 nuclease) was used in this study. S1 nuclease cleaved the unhybridized and loosely hybridized DNA's on the particles and enabled the determination of the fully complementary hybrid. This method saved us a troublesome labeling of the samples.

Monodisperse, thermosensitive microspheres with sub-micron diameters are used for separation and collection of proteins and other biomolecules. The thermosensitivity gives the microspheres two valuable features. One is the controllability of affinity between microsphere and protein with temperature. The quality and quantity of proteins to be adsorbed on the microspheres can be controlled with temperature. The other feature is reversible control of dispersion stability. Microspheres which have adsorbed target proteins in the dispersion can be easily recovered by changing temperature.

正常なDNA鎖同士のハイブリダイゼーションと片方のDNAにだけ点変異がある場合のハイブリダイゼーションとでは、後者のほうが結合力が弱いことがわかった。そこで微粒子にDNA一本鎖を固定化して、点変異DNAだけが検出できるように種々の条件の設定を行い、その検出に成功した。

様々な高分子表面による好中球の活性化について検討を行った。電荷を導入した表面および疎水性の表面は一過性であるが強く細胞を活性化させ、親水性の表面は弱いが持続的に細胞を活性化させることがわかった。

N,N-ジメチルアクリルアミド存在下でアクリルアミドの逆相マイクロエマルジョン重合を行った。

これまで作製されてきた感温性ゲル微粒子のサイズ変化は連続的であった。そこで架橋点をなくするためにコア微粒子からのN-イソプロピルアクリルアミドのグラフト重合を行った。さらにモノマーにアクリル酸を少量加えることにより不連続なサイズ変化を示す微粒子の作製が出来るようになった。

Surface topography plays an important role in cell orientation and morphogenesis. In this study, we prepared a micropatterned surface with settling particles to obtain more detailed information about the cell recognition against the microstructured surface. Core-shell type particles having a poly-(N-isopropylacrylamide) (polyNIPAM) shell were prepared by seeded polymerization. Particles were settled on a polystyrene (PSt) flat dish by the spinner to prepare a micropatterned surface with settling particles. It could be seen that the polyNIPAM shell shrunk above and swelled below the LCST. For comparison, a thermosensitive flat surface was prepared by the graft polymerization of NIPAM. No morphologic change of cells contacting the both surfaces was observed with either an optical or a scanning electron microscope. Moreover, particles could move or roll on these surfaces when shaking the dishes. The weak interaction between neutrophil-like cells and the micropatterned surface with settling particles or the polyNIPAM-grafted surface was estimated by measurement of active oxygen released by cells. A little release could be observed at both 25 and 35°C. The amount of released active oxygen at 35°C was slightly larger than at 25°C. When the temperature was suddenly changed, the dynamic changes of particle shape and size resulted in the excess release of active oxygen from cells contacting the micropatterned surface with settling particles. Meanwhile no stimulation could be observed in the polyNIPAM-grafted surface even if the temperature is suddenly changed. These results indicate that the micropatterned surface with settling particles can induce the dynamic stimulus at a patterned input mode.

二量化したペプチド断片の微粒子への固定化を行った。この微粒子を用いて二量化ペプチド断片と結合する核内タンパク質の単離を試みた。

ポリエステルウレタンをオゾン処理し、水溶性でノニオン性のポリマーのグラフト化を行った。この改質ポリウレタンの血液適合性を調べたところ、良好な結果を得ることが出来た。

アクリルアミドとメタアクリル酸から刺激応答性ゲル微粒子を作製した。この微粒子はpHに応答したサイズ変化を示した。

一本鎖のDNAを微粒子に固定化し、そのDNAと相補的なDNAあるいはRNAの単離を試みたところ、短時間で簡便に回収できることがわかった。

様々な溶媒を用いて沈殿重合によりゲル微粒子の作製を行った。ゲル微粒子の生成と溶媒の性質との関係を見いだし、さらに重合途中の微粒子の核形成の過程を検出することにより沈殿重合についての新しい知見を得ることが出来た。

沈殿重合により反応性ゲル微粒子を作製し、機能化を目指した様々な改質を行った。

ノニオン性の開始剤を用いた乳化重合を行った。この開始剤は水溶性であり、静電的な反発力に起因する分散安定化効果がなくとも、この水溶性に由来する立体反発力により微粒子の生成がなされたものと考えられた。

Poly(N‐isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM‐containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature‐sensitive microspheres. Copyright © 1995 John Wiley & Sons, Ltd.

感温性ゲル微粒子に酵素を固定化し、温度変化による酵素活性の制御を行った。

感温性ポリマー鎖に酵素を固定化し、温度変化による酵素活性の制御を行った。

沈殿重合により粒子径が均一で、反応性部位を有する微粒子を作製した。その反応性部位を介して微粒子の両性化を行った。

膜レセプターと特異的に接着するペプチド断片を微粒子に固定化した。その微粒子を用いて顆粒球の膜レセプターの分離に成功した。