A Rapid and Facile Separation-Detection Integrated Strategy for Exosome Profiling Based on Boronic Acid-Directed Coupling Immunoaffinity

Exosomes are a promising noninvasive tumor biomarker for cancer diagnosis and classification. However, efficient capture and precise analysis of exosomes in complex biological samples remain challenging. Here, sensitive profiling of exosomes with an integrated separation-detection strategy of 37 min is performed based on boronic acid-directed coupling immunoaffinity. The modification of g-C₃N₄ nanosheets with boronic acid (BCNNS) contributes to antibody binding under physiological conditions, which is accompanied by fluorescence enhancement. When exosomes are captured by an antibody equipped with BCNNS, a decrease in fluorescence can be induced; moreover, using the dispersion property of BCNNS, the exosomes can be separated by a simple centrifugation step. The protocol shows a favorable sensitivity with a detection limit of 2484 particles/mL. By changing only the fused antibody, exosome phenotype information profiling can be achieved, and exosomes derived from four different cell lines (HeLa, HepG2, MCF-7, and MCF-10A) can be successfully distinguished. More significantly, the positive prediction accuracy results reach 100% for serum samples from different individuals and have the advantage of multiple parameters; thus, the method has great potential in noninvasive diagnosis and point-of-care testing.