A Home-Built Magnetic Particle-Based Automated System for Viral Detection in Large-Volume Wastewater

Enriching trace viruses in large-volume wastewater samples is essential to ensure the detection accuracy of wastewater-based epidemiology, yet it is limited by laborious operations and low recovery efficiency. Magnetic particle (MP)-based approaches have the potential for automating enrichment processing and are considered a convenient alternative. However, automated applications for large-volume samples are hindered by the lack of MPs with satisfactory properties. In this study, we presented a novel large-volume viral enrichment system composed of elaborately prepared MPs and an automated platform. Due to the high magnetic responsiveness, excellent dispersibility, and selective absorption performance of MPs, the system enabled the automatic processing of up to 180 mL of large-volume samples without requiring centrifugation or ultrafiltration. A 0.2 copies/mL experimental sensitivity was achieved in spiked samples, which is 25-fold more sensitive than previous automated studies. The practical applicability has been validated through testing real wastewater samples, demonstrating a 4.5-fold detection accuracy for SARS-CoV-2 monitoring compared with the traditional protocol. Overall, the successful explorations on the designs of MPs address the challenges for automatedly enriching large-volume samples and endow the system with simplicity and efficiency, which offer a novel alternative tool for large-scale epidemiological surveillance.