Biosystems Technology, Institute for Applied Life Sciences, Technical University Wildau, Hochschulring 1, D-15745 Wildau, Germany.
Fachbereich Physik, Philips University Marburg, Renthof 5, D-35032 Marburg, Germany.
Nanoscale. 2017 Feb 23;9(8):2814-2823. doi: 10.1039/c7nr00091j.
The combination of the biocatalytic features of enzymes with the unique physical properties of nanoparticles in a biohybrid system provides a promising approach for the development of advanced bioelectrocatalytic devices. This study describes the construction of photoelectrochemical signal chains based on CdSe/ZnS quantum dot (QD) modified gold electrodes as light switchable elements, and low molecular weight redox molecules for the combination with different biocatalysts. Photoelectrochemical and photoluminescence experiments verify that electron transfer can be achieved between the redox molecules hexacyanoferrate and ferrocene, and the QDs under illumination. Since for both redox mediators a concentration dependent photocurrent change has been found, light switchable enzymatic signal chains are built up with fructose dehydrogenase (FDH) and pyrroloquinoline quinone-dependent glucose dehydrogenase ((PQQ)GDH) for the detection of sugars. After immobilization of the enzymes at the QD electrode the biocatalytic oxidation of the substrates can be followed by conversion of the redox mediator in solution and subsequent detection at the QD electrode. Furthermore, (PQQ)GDH has been assembled together with ferrocenecarboxylic acid on top of the QD electrode for the construction of a funtional biohybrid architecture, showing that electron transfer can be realized from the enzyme over the redox mediator to the QDs and subsequently to the electrode in a completely immobilized fashion. The results obtained here do not only provide the basis for light-switchable biosensing and bioelectrocatalytic applications, but may also open the way for self-driven point-of-care systems by combination with solar cell approaches (power generation at the QD electrode by enzymatic substrate consumption).
在生物杂化系统中，将酶的生物催化特性与纳米粒子的独特物理性质相结合，为开发先进的生物电化学催化装置提供了有前途的方法。本研究描述了基于 CdSe/ZnS 量子点 (QD) 修饰金电极作为光开关元件的光电化学信号链的构建，以及用于与不同生物催化剂结合的低分子量氧化还原分子。光电化学和光致发光实验验证了在光照下，氧化还原分子铁氰化钾和二茂铁之间以及 QD 之间可以实现电子转移。由于对于两种氧化还原介体都发现了浓度依赖性的光电流变化，因此用光开关酶信号链构建了果糖脱氢酶 (FDH) 和吡咯喹啉醌依赖性葡萄糖脱氢酶 ((PQQ)GDH)，用于检测糖。在将酶固定在 QD 电极上之后，可以通过将溶液中的氧化还原介体转化并随后在 QD 电极上进行检测来跟踪生物催化氧化反应。此外，(PQQ)GDH 已与二茂铁羧酸一起组装在 QD 电极的顶部，用于构建功能性生物杂化结构，表明电子可以从酶通过氧化还原介体转移到 QD 上，并随后以完全固定的方式转移到电极上。这里获得的结果不仅为光开关生物传感和生物电化学催化应用提供了基础，而且还可能通过与太阳能电池方法（通过酶底物消耗在 QD 电极上发电）结合，为自驱动即时检测系统开辟道路。
