Electrochemical Surface Enhanced Raman Spectroscopy of Pyocyanin Secreted by Pseudomonas Aeruginosa Communities

Pyocyanin (PYO) is one of many toxins secreted by the opportunistic human pathogenic bacterium Pseudomonas aeruginosa. Direct detection of PYO in biofilms is crucial, since PYO can provide important information about infection-related virulence mechanisms in P. aeruginosa. Because PYO is both redox active and Raman active, we seek to simultaneously acquire both spectroscopic and redox state information about PYO. The combination of surface-enhanced Raman spectroscopy (SERS) and voltammetry is used here to provide insights into the molecular redox behavior of PYO while controlling the SERS and electrochemical (EC) response of PYO with external stimuli, such as pH and applied potential. Furthermore, PYO secretion from biofilms of different P. aeruginosa strains is compared. Both SERS spectra and electrochemical behavior are observed to change with pH, and several pH-dependent bands are identified in the SERS spectra, which can potentially be used to probe the local environment. Comparison of the voltammetri...