D.L. Bellin, H. Sakhtah, J.K. Rosenstein, P.M. Levine, J. Thimot, K. Emmet, L.E.P. Dietrich, and K.L. Shepard Integrated circuit-based electrochemical sensor for spatially resolved detection of redox-active metabolites in biofilms, Nature Communications 5:3256 (2014) doi:10.1038/ncomms4256
Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites that are produced by microbial biofilms and can affect their development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. ‘Images’ over a 3.250.9mm2 area can be captured with a diffusion-limited spatial resolution of 750 μm. We demonstrate that square wave voltammetry can be used to detect, identify and quantify (for concentrations as low as 2.6 μm) four distinct redox-active metabolites called phenazines. We characterize phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of phenazine biosynthetic gene expression.