Development of biosensing methods for extracellular neuronal messengers and their application to in situ detection in acute brain slices

The present paper describes the development of biosensing methods for extracellular neuronal messengers, L-glutamate and arachidonic acid, and their application to in situ detection in acute brain slices. The methods include and an L-glutamate microsensor based on the capillary action of glass capillaries, an L-glutamate imaging method based on glutamate oxidase-horseradish peroxidase (GluOx-HRP) membranes and an excised patch membrane sensor for arachidonic acid. The L-glutamate microsensor has achieved highly sensitive detection and low sampling volume, which is necessary to minimize physical and chemical perturbations to brain slices. With the GluOx-HRP membrane combined with a difference-image analysis, the time-resolved regional distribution of the L-glutamate flux in acute brain slices was visualized. An in situ sensor for arachidonic acid was developed based on the interaction between arachidonic acid and the phospholipid bilayer of excised patch membranes. The response characteristics of these biosensing methods were studied in terms of the working principle, dynamic range, sensitivity, selectivity and applicability to in situ detection in acute brain slices.