Electrochemical Sensors Based on MoS_x‐Functionalized Laser‐Induced Graphene for Real‐Time Monitoring of Phenazines Produced by Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen causing infections in blood and implanted devices. Traditional identification methods take more than 24 h to produce results. Molecular biology methods expedite detection, but require an advanced skill set. To address these challenges, this work demonstrates functionalization of laser-induced graphene (LIG) for developing flexible electrochemical sensors for P. aeruginosa based on phenazines. Electrodeposition as a facile approach is used to functionalize LIG with molybdenum polysulfide (MoS x ). The sensor's limit of detection (LOD), sensitivity, and specificity are determined in broth, agar, and wound simulating medium (WSM). Control experiments with Escherichia coli, which does not produce phenazines, demonstrate specificity of sensors for P. aeruginosa. The LOD for pyocyanin (PYO) and phenazine-1-carboxylic acid (PCA) is 0.19 × 10 −6 and 1.2 × 10 −6 m, respectively. Furthermore, the highly stable sensors enable real-time monitoring of P. aeruginosa biofilms over several days. Comparing square wave voltammetry data over time shows time-dependent generation of phenazines. In particular, two configurations-"Normal" and "Flipped"-are studied, showing that the phenazines time dynamics vary depending on how cells interact with sensors. The reported results demonstrate the potential of the developed sensors for integration with wound dressings for early diagnosis of P. aeruginosa infection.

Recent Developments in the Biological Activities, Bioproduction, and Applications of Pseudomonas spp. Phenazines

“…This strategy is presented as a simple and efficient process that can be used for a scale-up process. Zhou et al [ 81 ] developed electrochemical sensors based on laser-induced graphene for real-time monitoring of P. aeruginosa phenazines.…”

Direct Laser-Functionalized Au-LIG Sensors for Real-time Electrochemical Monitoring of Response of Pseudomonas aeruginosa Biofilms to Antibiotics

“…There are three peaks in the SWV curves: the first oxidation peak around −0.3 V is associated with PYO, while the second and third are respectively associated with 5-MCA (5methylphenazine-1-carboxylic acid) and PQS (2-heptyl-3-hydroxy-4-quinolone). 6,31,40 The peaks are first noticed after 12 h and kept increasing within 48 h and then decayed over time. It should be noted that the peak current is higher than our previous work with electrodeposited MoS x -LIG, and hence, shows higher sensitivity of L-Au/LIG to phenazines.…”

“…It should be noted that the peak current is higher than our previous work with electrodeposited MoS x -LIG, and hence, shows higher sensitivity of L-Au/LIG to phenazines. 31 To further confirm the presence of PYO in PA14 cultures, we performed Liquid chromatography -Mass Spectrometry (LC-MS). Figure S8 shows the MS ion images of synthetic PYO in LB and PA14 culture in LB at 18 h after incubation.…”

“…Two strains of P. aeruginosa were studied: PA14 and ATCC 9027, which according to our previous work, is a defective mutant and does not produce PYO on LB agar. 31 At different time points, LB agar with bacteria was dropped into 1 ml PBS, followed by ultrasonication to dislodge cells from agar. Fig.…”

“…In our previous work, 31 we studied the production of phenazines in P. aeruginosa colony biofilms using electrochemical sensors based on laser induced graphene (LIG) manufactured using a facile, affordable, and environmentally-friendly process which also allows flexibility in the sensor design. We showed that the sensors are ideally suited for real time study of the dynamics of phenazine production over several days.…”