Amperometric Biosensors for Detection of Analytes in Cellular Models

Various biological problems such as disease mechanisms, drug development and toxicological studies motivated the introduction of cellular models that today also represent an alternative for reducing the use of animals in controversial medical and pharmaceutical experiments. Cells are complex matrices where several processes occur simultaneously. Because of this, analytical methods with specific paramenters (high sensitivity, response time, good selectivity) are required to efficiently monitor the behaviour and interaction of cells after stimulation with different kinds of compounds: drugs, toxic chemicals, etc. This thesis presents the currently used techniques for monitoring analytes of biomedical importance in cells and cell lines. Special attention is given to amperometric biosensors for the analysis of analytes released by cells. Different biosensor designs are presented, namely; enzyme-modified planar array, and dual needle type ones. The importance of key parameters, such as; recognition elements, immobilisation techniques, miniaturisation, and interference elimination is also discussed in detail and their application possibilities are presented for the case of some neurotransmitters. The design and the application possibilities of the developed biosensors are characterised by an increasing degree of complexity, ranging from simple graphite electrodes to needle type, micro-dual barrel Pt microelectrodes for the simultaneous detection of neurotransmitters released from cells. The thesis demonstrates that amperometric biosensors can be used in complex experiments to analyse the response of cells to different drugs and stress-induced mechanisms in cell cultures. Further application possibilities include the integration of biosensors with advanced imaging techniques, such as e.g. with scaning electrochemical microscopy (SECM)