3D plasmonic nanobowl platform for the study of exosomes in solution.

Thin silver film coated nanobowl Surface Enhanced Raman Spectroscopy (SERS) substrates are used to capture exosomes in solution for SERS measurements that can provide biochemical analysis of intact and ruptured exosomes. Exosomes derived via Total Exosome Isolation Reagent (TEIR) as well as ultracentrifugation (UC) from the SKOV3 cell line were analyzed. Spectra of exosomes derived via TEIR are dominated by a signal characteristic for the TEIR kit that needs to be subtracted for all measurements. Differences in SERS spectra recorded at different times during the drying of the exosome solution are statistically analyzed with Principal Component Analysis (PCA). At the beginning of the drying process, SERS spectra of exosomes exhibit peaks characteristic for both lipids and proteins. Later on during the drying process, new SERS peaks develop, suggesting that the initially intact exosome ruptures over time. This time-dependent evolution of SERS peaks enables analysis of exosomal membrane contents and the contents inside the exosomes.