(Invited) Targeting Sustainability in Bioelectrochemical Systems for Water Quality Monitoring

Abstract

Bioelectrochemical systems provide a sustainable approach to perform in-situ water quality monitoring, enabling the on-line detection of harmful contaminants in water samples. Specifically, interfacing intact microorganisms with abiotic electrodes allows developing bioelectrochemical systems for the early monitoring of several heavy metals and organic contaminants. Reports of microbial electrochemical sensors showed that a great number of contaminants can be monitored, achieving relevant sensitivity and stability.1 However, the sustainability of the utilized approaches, from biosensor setup to the choice of electrode materials, is not always considered, potentially limiting the applicability of the technology in the field.Here, focus is posed on the importance of targeting sustainability from the development to the application of microbial electrochemical sensors. Accordingly, a bio-inspired and bio-compatible approach for bacteria immobilization and redox mediation, as well as a bio-compatible route for electrode material development will be presented. Anoxygenic photosynthetic purple bacteria are utilized as the biophotocatalyst of choice, thanks to their extremely versatile metabolism where solar energy powers the oxidation of a broad variety of organic compounds. The use of these photosynthetic organisms is further motivated by their capability to cope and adapt to various environmental conditions (i.e., saline and non-saline environments, variable illumination conditions, presence of heavy metals)2, 3, making them of particular interest for applications in the field.4 Inspired by the natural approach utilized by mussels to obtain adhesive plaques, we explored an engineered deposition of polydopamine (PDA) for bacteria immobilization. The bio-inspired approach ensured firmly anchored purple bacteria on abiotic electrode surfaces while providing exogenous redox mediators to enhance photoexcited electrons harvesting. Focusing on the electrode material, we investigated the use of polyhydroxylkanoates (PHAs), biopolymers accumulated by a number of microorganisms, as biopolymer matrix to obtain homogeneous, flexible and free-standing electrodes. The coupling of these electrodes with photosynthetic bacteria for biophotoanodes development will be discussed, presenting advantages as well as future possibilities and challenges. References Chen, H.; Simoska, O.; Lim, K.; Grattieri, M.; Yuan, M.; Dong, F.; Lee, Y. S.; Beaver, K.; Weliwatte, S.; Gaffney, E. M.; Minteer, S. D. Chem. Rev. 2020, 120, 12903-12993.Giotta, L.; Agostiano, A.; Italiano, F.; Milano, F.; Trotta, M. Chemosphere 2006, 62, 1490-9.Gaffney, E. M.; Grattieri, M.; Beaver, K.; Pham, J.; McCartney, C.; Minteer, S. D. Electrochim. Acta 2020, 337, 135731.Grattieri, M. Photochem. Photobiol. Sci. 2020, 19, 424-435.