Härtl Andreas, Baur Barbara, Stutzmann Martin, Garrido Jose A
Walter Schottky Institut, Technische Universität München, Garching, Germany.
Langmuir. 2008 Sep 2;24(17):9898-906. doi: 10.1021/la8014139. Epub 2008 Aug 9.
Enzyme-modified field effect transistors (ENFETs) were realized using surface-conductive single-crystalline diamond films. The enzymes penicillinase and acetylcholinesterase were immobilized onto the active area of diamond-based electrolytic solution gated FETs, using different organic linker molecules and cross-linking chemistries. The active area of the devices was patterned to generate enzyme-modified regions next to surface-conductive regions. Penicillinase was chosen as a robust model system, but the main focus of the present paper is on acetylcholinesterase, an enzyme essential for many neuronal signal transduction processes. All the different ENFETs show a clear and specific response to the corresponding substrate, penicillin and acetylcholine. The device response is based on the pH sensitivity of the surface-conductive active area and is enabled by the local pH change induced during the enzymatic reaction. The devices demonstrate promising stability and characteristic variations of the enzymatic activity with measurement conditions. Furthermore, the results from the ENFET measurements were compared with the results of spectrophotometric experiments, carried out with enzymes immobilized on diamond substrates and also with free enzymes in solution. This allows an analysis of the enzyme kinetics, as well as qualitative comparison of the different functionalization methods employed in this study.
酶修饰场效应晶体管（ENFET）是利用表面导电的单晶金刚石薄膜实现的。使用不同的有机连接分子和交联化学方法，将青霉素酶和乙酰胆碱酯酶固定在基于金刚石的电解液栅极场效应晶体管的有源区上。对器件的有源区进行图案化处理，以在表面导电区域旁边生成酶修饰区域。选择青霉素酶作为一个稳健的模型系统，但本文的主要重点是乙酰胆碱酯酶，它是许多神经元信号转导过程所必需的一种酶。所有不同的ENFET对相应的底物青霉素和乙酰胆碱都表现出清晰而特异的响应。器件响应基于表面导电有源区的pH敏感性，并由酶促反应过程中引起的局部pH变化实现。这些器件在测量条件下展现出有前景的稳定性和酶活性特征变化。此外，将ENFET测量结果与分光光度实验结果进行了比较，分光光度实验是用固定在金刚石基底上的酶以及溶液中的游离酶进行的。这使得能够分析酶动力学，以及对本研究中采用的不同功能化方法进行定性比较。
