Characterization of Biosensor Surface by Scanning Electrochemical Microscopy

Application of Scanning Electrochemical Microscopy (SECM) is spreading very fast. The SECM based techniques are very attractive for the evaluation of biological materials and investigation of other important parameters in bioelectrochemistry, such as enzyme kinetics, heterogeneous electron transfer kinetics, and diffusion. The main part of SECM is Ultramicroelectrode (UME), which can characterize electrochemically conducting surfaces by measuring current flowing through electrode at selected point of specimen. The well-known enzyme glucose oxidase (GOx), immobilized on insulating substrate and immersed in glucose containing solution, is applied for the development of biosensor models and surfaces of such GOx-based biosensors could be evaluated by SECM. The most important factor in biosensor design is enzyme activity, which depends on temperature, duration of experiments, pH and many other factors. In recent research the substrate generation/tip collection (GC) mode was used for SECM measurements of GOx-based surface. The scan in the horizontal direction provides concentration profile of hydrogen peroxide. The enzyme immobilization was controlled by Atomic Force Microscopy. The highest enzyme activity was registered in the center of enzyme drop.