Electrochemical Aptamer-Based Sensor for Measuring Astrocytic ATP Release

Abstract

The abnormal release of adenosine triphosphate (ATP) by astrocytes has been proposed as a potential astrocyte dysfunction in neurodegenerative diseases. However, the roles of astrocytic ATP release are not fully understood, in part because of the lack of analytical tools. Electrochemical aptamer-based (E-AB) sensors can be utilized for the quantification of ATP released by astrocytes, providing insight into the function of this release in the brain. E-AB sensors use aptamers, oligonucleotides that bind a specific target such as ATP, to measure target concentration. These aptamers undergo a conformational change upon target binding, resulting in an increase in current that is quantitatively related to ATP concentration. We have optimized a micro-cylinder ATP E-AB sensor that will be used to make bulk measurements of ATP released from astrocytes cultured in a three-dimensional (3-D) collagen hydrogel serving as an in vivo mimic. In order to make these measurements, we performed calibration titrations to determine the percent signal changes corresponding to different ATP concentrations at room temperature and 37°C. We found that the optimal frequencies used in square wave voltammetry for current measurements increased with increasing temperature. These new optimal frequencies will be used for measurements using cells cultured in a collagen hydrogel.