Fig. 1

Proteomic data for individual sEVs from youth (20–30 years old, n = 44) and senior (60–84 years old, n = 45) serum samples were analyzed by PBA. A. Schematic diagram of the PBA. PBA probes were antibodies with chemical conjugation of barcoding DNA oligonucleotides, which included 8-nt protein tag to specify each protein and 8-nt molecular tag to distinguish protein molecules. The 3’- part of DNA oligonucleotides on PBA probes were able to hybridize to the RCA product with repeated segments containing the same unique 15-nt EV tag. After extension reaction, the PBA probes on the same EV were incorporated with the EV tag. The whole sequences were employed to analyze the links between EV tag and related protein type and molecular count. Therefore, the protein expression on single EVs was quantified. B. Electron microscope image of sEVs captured by PBA. C. The number of sEVs detected in each sample. D. The number of proteins detected in each sample. E. The number of proteins detected per sEV. F. Volcano plot of the proteomic data (Senior vs. Youth). G. ROC curve of sEV biomarkers for distinguishing between the senior group and the youth group. H. Significant GO terms and KEGG pathways for intergroup differential proteins