Nanostructured Biosensors with Ultra-Low Detection Limit and High Selectivity for Real-Time and Continuous Sewage Monitoring.

Wastewater-Based Epidemiology (WBE) has emerged as a powerful tool for rapid monitoring and forecasting community health trends. However, conventional WBE relies on real-time polymerase chain reaction (RT-PCR) techniques, which are reliable but time-consuming. Additionally, the batchwise sampling approach may not accurately provide a full picture of daily virus profile in sewage, potentially leading to misleading forecasts. In this study, we report printable electrochemical biosensors with an ultralow limit of detection (LOD) of 0.025 fg/mL and desirable stability for continuous monitoring of SARS-CoV-2 and H3N2 viruses in sewage. Such attractive characteristics can be attributed to the dendritic gold electrodes that provide a large and robust surface for immobilizing extra antibodies. Besides, the sensors possess metrics including rapid response and high selectivity against common sewage interferents. An integrated and portable sensing patch was further designed and demonstrates comparative reliability to standard qRT-PCR methods, offering a promising strategy for viral surveillance and outbreak management in WBE.