Immobilization Strategies for Enzymatic Biosensors based on Electrolyte-Gated Carbon Nanotube Transistors

In the fields of clinical diagnostics and point-of-care diagnosis as well as food and environmental monitoring there is a high demand for reliable high-throughput, rapid and highly sensitive biosensing assays for a simultaneous detection of several analytes in complex and low-volume samples. A biosensor in general consists of two important elements: the transducer and a biorecognition layer recognizing the analyte. Due to their solution-processability electrolyte-gated carbon nanotube filed-effect transistors (CNT-FETs) can be a simple, miniaturized and cost-effective alternative transducing element instead of conventional spectroscopic, voltammetric or chromatographic assays. By immobilizing an enzyme on the biosensor surface one can catalyse the reaction of a specific substrate to its products, which can further change the pH value on the sensor surface and can therefore be detected for example by a pH-sensitive CNT-FET. But especially the immobilization of enzymens on the sensor surface is a critical step in the design of such an enzymatic biosensor. Each immobilization method has a different influence on the main characteristics of the sensor performance: sensitivity, selectivity and stability. In this work we will apply different immobilization techniques to immobilize enzymes on the surface of an electrolyte-gated CNT-FET and compare their characteristic influence on the sensor response. The different functionalization strategies including layer-by-layer assembly, covalent binding, cross-linking and entrapment in a gel layer will be tested with several commonly used enzyme-substrate systems.      «

In the fields of clinical diagnostics and point-of-care diagnosis as well as food and environmental monitoring there is a high demand for reliable high-throughput, rapid and highly sensitive biosensing assays for a simultaneous detection of several analytes in complex and low-volume samples. A biosensor in general consists of two important elements: the transducer and a biorecognition layer recognizing the analyte. Due to their solution-processability electrolyte-gated carbon nanotube filed-effe...     »