Intact Photosynthetic Bacteria-Based Electrochemical Biosensors

Abstract

Utilizing photosynthetic entities in electrochemical systems enables converting solar energy into electrical energy, obtaining bio-hybrid photo-electrochemical systems. Such systems have been recently proposed for micro power generation, bioelectrosynthesis, and biosensing for in-situ water quality monitoring.[1] However, due to the photosynthetic apparatus in bacteria (i.e., purple bacteria and cyanobacteria) being physically separated from the electrode surface by the presence of various membrane layers, artificial approaches to divert the photoexcited electrons are required. As a result, research efforts have been focused on developing bio-compatible approaches to facilitate the transfer of photoexcited electrons from these bacteria to the electrodes (and vice versa).[2] Herein, a sustainable biophotoanode based on intact purple bacteria is utilized for the monitoring of phenol-class contaminants that affects photocurrent generation. Specifically, we focused on nitro-phenols and other phenols that might be released in water when food/agricultural wastes are disposed into the environment. All the investigated compounds are known to be toxic, affecting both humans and animals’ health. Furthermore, to follow the green chemistry and bio-circular economy principles, approaches for the possible removal/recovery of these phenols and their degradation products were also investigated, with their possible re-use as active compounds in biomedical applications.[3] Challenges and future research directions for the application of these systems in the field will be discussed.