A New Route to the Considerable Enhancement of Glucose Oxidase (GOx) Activity: The Simple Assembly of a Complex from CdTe Quantum Dots and GOx, and Its Glucose Sensing
A New Route to the Considerable Enhancement of Glucose Oxidase (GOx) Activity: The Simple Assembly of a Complex from CdTe Quantum Dots and GOx, and Its Glucose Sensing
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DOI：
10.1002/chem.200800681
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发表时间：
2008-01-01
影响因子：
4.3
通讯作者：
Tang, Bo
中科院分区：
文献类型：
--
作者：
Cao, Lihua;Ye, Jian;Tang, Bo
一种新的由CdTe量子点(Qds)和葡萄糖氧化酶(GOx)组成的络合物被很容易地组装起来，以获得显著增强的酶活性和较宽的活性温度范围：这些特征归因于GOx在ASS Semble过程中的构象变化。所得络合物可同时用作高灵敏度的葡萄糖纳米传感器。提出了一种基于CdTe量子点荧光猝灭的机理。这是由过氧化氢(H_2O_2)引起的，过氧化氢是GOX催化的葡萄糖氧化产生的。当双氧水到达CdTe量子点的表面时。电子转移反应立即发生，H_2O_2被还原为O-2，O-2位于CdTe量子点上的电子空穴陷阱中，可以作为良好的受体，从而形成无荧光的CdTe量子点阴离子。生成的O，可进一步参与GOX的催化反应。形成了葡萄糖氧化的循环电子转移机制。这对整个反应体系是有利的。GOX的米氏常数估计为0.45mM L-1，这表明到目前为止测得的酶活性有相当大的提高。此外，连接在CdTC量子点上的GOx酶在20-80℃具有较好的热稳定性，在40-50℃的宽范围内保持了最大的活性，而且作为纳米传感器简单组装的络合物可以灵敏地测定从微米到毫米级的宽浓度范围的葡萄糖，检测下限为0.10µM，可用于生物体系中低水平葡萄糖的直接检测。因此，所建立的方法可以为将CdTe量子点与其他氧化还原酶组装在一起，实现更高的酶活性，以及进一步设计未来应用于生物系统的新型纳米传感器提供一种途径。
A new complex consisting of CdTe quantum dots (QDs) and glucose oxidase (GOx) has been facilely assembled to achieve considerably enhanced enzymatic activity and a wide active temperature range of GOx: these characteristics are attributed to the conformational changes of GOx during ass sembly. The obtained complex can be simultaneously used as a nanosensor for the detection of glucose with high sensitivity. A mechanism is put forward based on the fluorescence quenching of CdTe QDs. which is caused by the hydrogen peroxide (H2O2) that is produced from the GOx-catalyzed oxidation of glucose. When H2O2 gets to the surface of the CdTe QDs. the electron-transfer reaction happens immediately and H2O2 is reduced to O-2 which lies in electron hole traps on CdTe QDs and can be used as a good acceptor, thus forming the nonfluorescent CdTe QDs anion. The produced 0, can further participate in the catalyzed reaction of GOx. forming a cyclic electron-transfer mechanism of glucose oxidation. which is favorable for the whole reaction system. The value of the Michaelis-Menton constant of GOx is estimated to be 0.45 mM L-1, which shows the considerably enhanced enzymatic activity measured by far. In addition, the GOx enzyme conjugated on the CdTc QDs possesses better thermal stability at 20-80 degrees C and keeps the maximum activity in the wide range of 40-50 degrees C. Moreover, the simply assembled complex as a nanosensor can sensitively determine glucose in the wide concentration range from micro- to millimolar with the detection limit of 0.10 mu M, which could be used for the direct detection of low levels of glucose in biological systems. Therefore, the eatablished method could provide an approach for the assembly of CdTe QDs with other redox enzymes, to realize enhanced enzymatic activity, and to further the design of novel nanosensors applied in biological systems in the future.