Pyocyanin detection during bacterial growth.

<p>Detection of pyocyanin in <i>P</i>. <i>aeruginosa</i> cultures during exponential and stationary growth in lysogeny broth (LB).</p

Paper-based sensors for rapid detection of virulence factor produced by <i>Pseudomonas aeruginosa</i>

<div><p>Pyocyanin is a toxin produced by <i>Pseudomonas aeruginosa</i>. Here we describe a novel paper-based electrochemical sensor for pyocyanin detection, manufactured with a simple and inexpensive approach based on electrode printing on paper. The resulting sensors constitute an effective electrochemical method to quantify pyocyanin in bacterial cultures without the conventional time consuming pretreatment of the samples. The electrochemical properties of the paper-based sensors were evaluated by ferri/ferrocyanide as a redox mediator, and showed reliable sensing performance. The paper-based sensors readily allow for the determination of pyocyanin in bacterial cultures with high reproducibility, achieving a limit of detection of 95 nM and a sensitivity of 4.30 μA/μM in standard culture media. Compared to the similar commercial ceramic based sensors, it is a 2.3-fold enhanced performance. The simple in-house fabrication of sensors for pyocyanin quantification allows researchers to understand <i>in vitro</i> adaptation of <i>P</i>. <i>aeruginosa</i> infections via rapid screenings of bacterial cultures that otherwise are expensive and time-consuming.</p></div

Sensor fabrication process.

<p>(a) Placement of the mask on top of the photo paper. (b) Manual scrapping of ink on top of the shadow mask. (c) shadow mask removal. (d) Photo paper with carbon screen printed electrodes.</p

Electrochemical characterization of the paper-based sensors.

<p>Evaluation of electrochemical sensor performance by (a) cyclic voltammograms (CV) at various scan rates in ferri/ferrocyanide. (b) The extracted peak currents are linearly proportional with the square roots of the scan rates denoting a quasi-reversible system suitable for analyte quantification. Measurements are conducted against the reference electrode.</p

Pyocyanin quantification.

<p>Detection of pyocyanin in lysogeny broth (LB) using the paper-based sensors. (a) Square wave voltammograms of increasing pyocyanin concentrations from 1–40 μM in LB. (b) Standard curve using the extracted peak currents as function of the pyocyanin concentration.</p

Comparison of sensor performances.

<p>Peak currents extracted from square wave voltammograms of 10 μM pyocyanin detected with commercial gold and carbon sensors compared to the new paper-based carbon sensors (PbS).</p