Unifying Ultrafiltration-on-a-Chip and Metamaterial Sensing for Extracellular Vesicle Diagnostics in Acute Kidney Injury

Acute kidney injury (AKI) affects over 13 million individuals globally, causes nearly 1.7 million deaths annually, and occurs in 20–40% of COVID-19 intensive care patients. Despite its prevalence and severity, the lack of efficient and reliable biomarkers continues to hinder early diagnosis and therapeutic monitoring. Extracellular vesicles (EVs) have recently emerged as promising next-generation biomarkers and nanocarriers for therapeutic applications; however, their isolation and analysis from complex biological fluids remain major obstacles to clinical translation. Here, we report a facile, rapid, and low-cost dual-platform technology for the isolation and characterization of urinary EVs from AKI patients. The system integrates an ultrafiltration-on-a-chip module and a nanostructured metamaterial sensor, both optimized for clinical feasibility. The ultrafiltration chip isolates EVs from cell culture and patient urine samples within an hour and at a material cost of around $5, yielding ~10⁹ vesicles/mL—comparable to conventional ultracentrifugation. The metamaterial sensor, fabricated by repurposing nanograting plastic substrates, is functionalized with EV-specific antibodies to enable label-free detection. This sensor exhibits ~100-fold higher sensitivity and a four-order-of-magnitude broader dynamic range than commercial ELISA assays. EV identity and purity were confirmed via NTA, fNTA, Western blotting, SEM, and XPS analyses. Furthermore, surface marker profiling using the metamaterial sensor successfully differentiated AKI patients from healthy controls through a comprehensive biomarker panel (ATF3, NGAL, THP, AQP1, CD133, and Fetuin A) in addition to tetraspanins. Collectively, this work for the first time introduces a clinically translatable, cost-effective, and high-performance EV-based platform for next-generation point-of-care diagnostics in AKI.

Funding: Dr. Inci thanks support from the TÜBİTAK Incentive Award and TÜBİTAK 2232 Program (118C254).