Microfluidic-based exosome isolation and highly sensitive aptamer exosome membrane protein detection for lung cancer diagnosis

Non-invasive methods of detecting cancer by circulating exosomes are challenged by inefficient purification and identification. This study hereby proposed an automated centrifugal microfluidic disc system combined with functionalized membranes (Exo-CMDS) to isolate and enrich exosomes, which will then be processed by a novel aptamer fluorescence system (Exo-AFS) in order to detect the exosome surface proteins in an effective manner. Exo-CMDS features in highly qualified yields with optimal exosomal concentration of 5.1 × 10⁹ particles/mL from trace amount of blood samples (<300 μL) in only 8 min, which truly accomplishes the exosome isolation and purification in one-step methods. Meanwhile, the limit of detection (LOD) of PD-L1 in Exo-AFS reaches as low as 1.58 × 10⁵ particles/mL. In the trial of clinical samples, the diagnostic accuracy of lung cancer achieves 91% (95% CI: 79%-96%) in contrast to the exosome ELISA (area under the curve: 0.9378 versus 0.8733; 30 patients). Exo-CMDS and Exo-AFS display the precedence in the aspects of inexpensiveness, celerity, purity, sensitivity and specificity when compared with the traditional techniques. Such assays potentially grant a practicable way of detecting inchoate cancers and guiding immunotherapy in clinic.