Antifouling fusion-mediated diagnostic platform to detect viral DNA-positive extracellular vesicles for in situ blood-based liquid biopsy

In liquid biopsy, extracellular vesicles (EVs) have emerged as promising biomarkers due to their ability to carry protected nucleic acids. In particular, DNA enclosed within these vesicles shows great diagnostic potential for monitoring oncovirus-related disease progression. However, current methods still require labor-intensive procedures and bulk analysis. Additionally, in situ detection from blood is hindered by abundant serum proteins, interfering with the accuracy of diagnosis. To address these limitations, we developed an antifouling fusion-mediated CRISPR/Cas detector (AFFECTOR) as a user-friendly and efficient diagnostic platform for directly detecting EV-contained viral DNA in serum samples. Leveraging zwitterionic phosphatidylcholine to resist protein interference, the platform enables stable membrane fusion with intact EVs even in serum-containing environments, allowing highly specific and sensitive detection of internal DNA via the CRISPR/Cas12a sensing system, lasting just 2 h at 37 °C. In clinical samples from oncovirus-infected patients and healthy donors, the platform achieved one-step detection of viral DNA-positive EVs. Notably, viral DNA in circulating EVs was found for the first time to correlate with oncovirus infection stages. Overall, this platform provides a practical tool for diagnostic applications and expands the detection window in liquid biopsy.