SECM investigation on pH changes in cellular environment induced by caffeine

Abstract

This work shows the results of the fabrication and application of a potentiometric microsensor for real-time pH monitoring in the vicinity of C2C12 cell line muscle cells using Scanning Electrochemical Microscopy (SECM). This was achieved by electrodeposition of an iridium oxide film onto the surface of a dual sensor containing two microelectrodes (Au and Pt). The Au microelectrode was coated with an iridium oxide film and used as a potentiometric pH sensor. The sensor exhibited a super Nernstian response (around 70 mV pH−1), and its precise positioning above a single C2C12 cell was accomplished by means of an approach curve recorded with the Pt microelectrode. pH changes were induced by changing the cellular metabolism through the addition of caffeine to the culture medium, and an average decrease of up to 0.5 units in pH was noticed by measuring the pH at 10 µm from the cell surface. Much smaller pH changes were observed in control experiments, confirming that caffeine induces acidosis and that such a phenomenon can be monitored using the fabricated dual sensor coupled to SECM.