*High-Throughput Single Extracellular Vesicle Profiling DOI: http://dx.doi.org/10.5772/intechopen.97544*

(RCA) products were prepared from circularized oligonucleotides comprising a 15-nt random sequence. Because15-nt random sequence are capable of encoding 415 (about one billion) unique sequences to work as EV tags, RCA products are utilized as templates to barcode antibody conjugated oligonucleotides on single EVs (**Figure 14b**). EVs were incubated with PBA probes and then captured via immobilized cholera toxin subunit B (CTB). Oligonucleotides on PBA probes brought together by binding the same EV are allowed to hybridize to a unique RCA product and therefore obtain the same EV tag via enzymatic extension. Successfully extended DNA molecules on PBA probes are amplified by PCR. The PCR product were subjected to DNA sequencing to record the combinations of EV tag - protein tag thus revealing the proteomic profiles of individual EVs.

In the study of 38-plex PBA analysis, individual EVs of 16 types of cell lines, prostasome and serum could be profiled. The information researchers could obtain includes protein expression and the pattern of protein combinations on individual EVs. The differences of samples were visualized by t-SNE according to their protein compositions.
