In-situ and continuous monitoring of pyocyanin in the formation process of Pseudomonas aeruginosa biofilms by an electrochemical biosensor chip

Abstract Pyocyanin is a specific virulence factor and quorum sensing (QS) signal molecule of Pseudomonas aeruginosa, and plays an important role in biofilm formation. In this paper, a biosensor chip was proposed and fabricated for the long term cultivation of Pseudomonas aeruginosa biofilms and in-situ monitoring of pyocyanin. The biosensor chip consisted of two parts, a top polydimethylsiloxane (PDMS) layer with micro-channels and micro-chambers for providing an adequate microenvironment for Pseudomonas aeruginosa biofilm growth, and a bottom microelectrode integrated on a glass substrate for monitoring the QS virulence factor and Pseudomonas aeruginosa biofilms. The concentration of pyocyanin was monitored by AuNPs-modified microelectrodes by differential pulse voltammetry (DPV) on the designed chip. It was demonstrated that the change in pyocyanin concentration was closely related to the developing process of the Pseudomonas aeruginosa biofilms. In addition, the effect of curcumin, a Chinese herb QS inhibitor, on pyocyanin and biofilm production was investigated and analyzed. The results indicate that curcumin inhibited the growth of Pseudomonas aeruginosa biofilms and reduced the production of pyocyanin. The designed biosensor chip provides a promising microenvironment for the quantitative monitoring of pyocyanin in the formation of biofilms and acts as a platform for investigating the mechanism behind anti-bacterial agents.