Photobioelectrochemical sensor based on WO3 modified by chloroplast as a platform for simazine detection in environmental waters

Photobioelectrochemical systems have gained prominence in environmental contaminant monitoring due to their high sensitivity, selectivity, and ability to operate under visible light. In this study, we investigated the incorporation of chloroplasts, the organelle responsible for photosynthesis, into a tungsten trioxide (WO₃) n-type semiconductor electrode modified with a thin polydopamine (PDA) layer. PDA plays a crucial role in efficiently immobilizing chloroplasts, facilitating electron transfer, and enhancing light energy conversion. The biosensor's performance was evaluated based on its photocurrent response in the presence and absence of simazine (SMZ), a widely used herbicide classified as an emerging pollutant. The proposed methodology exhibited a linear response in the range of 0.005 to 10.0 μM, with a detection limit of 0.002 μM (0.410 ppb) and a quantification limit of 0.004 μM (0.759 ppb). Its application in aqueous samples (tap, mineral, river, groundwater) demonstrated good recovery rates. The electrode efficiency response was compared with chromatographic analysis (LC/MS/MS and GC/MS), which provided similar results, confirming the accuracy and reliability of the device. Additionally, the sustainability of the method was assessed using AGREE software, where the biosensor achieved a score of 0.78, indicating a significantly greener profile compared to the chromatograph (score of 0.55). This study establishes the chloroplast-based biophotoelectrode as a viable, sustainable, and cost-effective alternative for SMZ herbicide monitoring in environmental samples, combining analytical efficiency with reduced environmental impact.