Visual Quantitative Detection of Tumor-Derived Exosomes Based on Catalyzed Decomposition of H 2 O 2 Using a Portable Microchannel Device

Current diagnostic methodologies are predominantly characterized by intricate procedures and reliance on expensive instrumentation, thereby limiting their applicability for point-of-care testing (POCT). In this study, a portable pressure-based visual biosensor (PVB) is developed for rapid and quantitative analysis of tumor-derived exosomes with smartphone assistance for breast cancer diagnosis. CD63 and mucin1 (MUC1) aptamers are employed to recognize exosomal membrane proteins, forming a magnetic bead (MB)-exosome-platinum nanoparticle (PtNP) sandwich complex. Through a simple inversion of the microchannel device, MUC1-positive exosomes can be quantitatively detected by measuring the displacement of the stained substrate, which is positively correlated to the oxygen (O₂) generated through PtNP-catalyzed decomposition of hydrogen peroxide (H₂O₂). This strategy enables efficient analysis of MUC1-positive exosomes within 25 min using smartphone imaging, demonstrating a limit of detection (LOD) of 496 particles/μL. Clinical trial results revealed that this method effectively differentiated breast cancer patients from healthy controls, achieving a diagnostic concordance rate of 84.62%. In addition to advantages such as being instrument-free, user-friendly, and lowcost, this technique can be quickly extended and provides a practical approach to the rapid analysis of various biomarkers.