Department of Applied Molecular Bioscience, Yamaguchi University , 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
ACS Appl Mater Interfaces. 2014 Mar 12;6(5):3671-9. doi: 10.1021/am405992t. Epub 2014 Feb 27.
Mechanosensitive liposomes were prepared and applied to continuously accelerate the glucose oxidase (GO) reaction in shear flow. The liposome membrane was composed of a ternary lipid mixture containing 20 mol % negatively charged lipid and 30 mol % cholesterol. The liposomes encapsulating GO and catalase were passed through microtubes with inner diameter of 190 or 380 μm at 25 °C to induce the catalytic oxidation of 10 mM glucose with simultaneous decomposition of H2O2 produced. The liposomal GO showed significantly low reactivity in the static liquid system because of the permeation resistance of lipid membranes to glucose. On the other hand, the enzyme activity of liposomal GO observed at the average shear rate of 7.8 × 10(3) s(-1) was significantly larger than its intrinsic activity free of mass transfer effect in the static liquid system. The structure of liposomes was highly shear-sensitive as elucidated on the basis of shear rate-dependent physical stability of liposomes and membrane permeability to 5(6)-carboxyfluorescein as well as to GO. Thus, the above shear-driven acceleration of GO reaction was indicated to be caused by the free GO molecules released from the structurally altered liposomes at high shear rates. Moreover, the shear-induced denaturation of free GO was completely depressed by the interaction with the sheared liposomes with the chaperone-like function. The shear-sensitive liposomal GO system can be a unique catalyst that continuously accelerates and also decelerates the oxidation reaction depending on the applied shear rate.
机械敏感性脂质体被制备并应用于连续加速剪切流中的葡萄糖氧化酶（GO）反应。脂质体膜由含有 20 mol%带负电荷脂质和 30 mol%胆固醇的三元脂质混合物组成。包封 GO 和过氧化氢酶的脂质体在 25°C 下通过内径为 190 或 380μm 的微管，以诱导 10mM 葡萄糖的催化氧化，同时分解产生的 H2O2。由于脂质膜对葡萄糖的渗透阻力，脂质体 GO 在静态液体系统中表现出明显较低的反应性。另一方面，在平均剪切速率为 7.8×10(3) s(-1)下观察到的脂质体 GO 的酶活性明显大于其在静态液体系统中无传质效应的固有活性。基于脂质体的剪切速率依赖性物理稳定性以及 5(6)-羧基荧光素和 GO 对脂质体膜的通透性，阐明了脂质体的结构对剪切非常敏感。因此，GO 反应的上述剪切驱动加速被认为是由高剪切速率下从结构改变的脂质体中释放的游离 GO 分子引起的。此外，具有类似伴侣的功能的剪切脂质体与游离 GO 的相互作用完全抑制了游离 GO 的剪切诱导变性。剪切敏感的脂质体 GO 系统可以是一种独特的催化剂，它可以根据施加的剪切速率连续加速和减速氧化反应。
