Real-Time Monitoring of Bacterial Metabolites By Scanning Electrochemical Microscopy (SECM)

Abstract

Scanning Electrochemical Microscopy (SECM) is used to study the local chemical environment above live bacterial biofilms such as S. gordonii (Sg), S. mutans (Sm) etc. In this study, we report the development of a Pt decorated carbon nanotubes (CNTs) based dual SECM probe to detect low micro-molar range hydrogen peroxide (H2O2) produced by the live bacterial biofilm. This sensor showed sensitivity 2.2 ± 5 mA cm-2 mM-1 with low detection limit of 0.5 µM. Our results indicate that the Sg produced 65-70 μM H2O2 within 30 min in presence of 1 mM glucose in artificial saliva solution (pH 7.2) at 37°C. In addition, we have also developed a unique solid state carbon based potentiometric pH sensor and used as a SECM probe to map the pH change at high spatial resolution above the Sg biofilm. The sensor showed Nernstian response with slope of 58±4 and very fast response time of 5s. The pH mapping above the biofilm showed that pH above the biofilm dropped by one pH unit within 30 min only in 6 pH artificial saliva with 30 mM sucrose at 37°C. Recent developments about the real-time metabolic exchange between two bacterial species (Sg and Sm) in terms of peroxide and pH will be presented in the conference. Figure 1