Online-monitoring of biofilm formation using nanostructured electrode surfaces

The direct monitoring of biofilm formation enables valuable insights into the industrial processes, microbiology, and biomedical applications. Therefore, in the present study, nano-structured bioelectrochemical platforms were designed for sensing the formation of biofilm of P. aeruginosa along with monitoring its electrochemical/morphological changes under different stresses. Through the assay optimizations, the performances of different electrode modifiers such as reduced graphene oxide (rGO) nanosheets, hyperbranched chitosan nanoparticles (HBCs NPs), and rGO-HBCs nano-composite were tested to assess the influence of the electrode materials on biofilm progression. As a need for the anodic respiration, the bioelectrochemical responses of the adhered bacterial cells changed from a non-electrochemically active (planktonic state) to an electrochemically active (biofilm matrix) state. Our results demonstrated that electrode modifications with conductive nanostructured elements is highly sensitive and enable direct assay for the biofilm formation without any preachments. Consequently, the morphological changes in bacterial cell wall, upon switching from the planktonic state to the biofilm matrix were imaged using scanning electron microscopy (SEM), and the changes in cell wall chemical composition were monitored by the Energy Dispersive X-ray analysis (EDX). Thus, the designed microbial electrochemical system (MES) was successfully used to monitor changes in the biofilm matrix under different stresses through direct measurements of electron exchanges.