化学
尿素
尿素酶
辣根过氧化物酶
磁导率
膜
化学工程
纳米反应器
两亲性
动力学
催化作用
氨
共聚物
有机化学
生物化学
酶
聚合物
物理
量子力学
工程类
作者
Wouter P. van den Akker,Hanglong Wu,Pascal L W Welzen,Heiner Friedrich,Loai K. E. A. Abdelmohsen,Rolf A. T. M. van Benthem,Ilja K. Voets,Jan C. M. van Hest
摘要
We demonstrate the construction of pH-responsive bicontinuous nanospheres (BCNs) with nonlinear transient permeability and catalytic activity. The BCNs were assembled from amphiphilic block copolymers comprising pH-responsive groups and were loaded with the enzymes urease and horseradish peroxidase (HRP). A transient membrane permeability switch was introduced by employing the well-known pH-increasing effect of urease upon conversion of urea to ammonia. As expected, the coencapsulated HRP displayed a transiently regulated catalytic output profile upon addition of urea, with no significant product formation after the pH increase. This transient process displayed a nonlinear "dampening" behavior, induced by a decrease in membrane permeability as a result of significant local ammonia production. Furthermore, the catalytic output of HRP could be modulated by addition of different amounts of urea or by altering the buffer capacity of the system. Finally, this nonlinear dampening effect was not observed in spherical polymersomes, even though the membrane permeability could also be inhibited by addition of urea. The specific BCN morphology therefore allows to optimally control catalytic processes by pH changes in the nanoreactor microenvironment compared to bulk conditions due to its unique permeability profile.
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