Correlation between Cancerous Exosomes and Protein Markers Based on Surface-Enhanced Raman Spectroscopy (SERS) and Principal Component Analysis (PCA)

Abstract

Exosomes, which are nanovesicles secreted by cells, are promising biomarkers for cancer diagnosis and prognosis, based on their specific surface protein compositions. Here, we demonstrate the correlation of nonsmall cell lung cancer (NSCLC) cell-derived exosomes and potential protein markers by unique Raman scattering profiles and principal component analysis (PCA) for cancer diagnosis. On the basis of surface enhanced Raman scattering (SERS) signals of exosomes from normal and NSCLC cells, we extracted Raman patterns of cancerous exosomes by PCA and clarified specific patterns as unique peaks through quantitative analysis with ratiometric mixtures of cancerous and normal exosomes. The unique peaks correlated well with cancerous exosome ratio (R 2 > 90%) as the unique Raman band of NSCLC exosome. To examine the origin of the unique peaks, we compared these unique peaks with characteristic Raman bands of several exosomal protein markers (CD9, CD81, EpCAM, and EGFR). EGFR had 1.97-fold similarity in Raman profiles than other markers, and it showed dominant expression against the cancerous exosomes in an immunoblotting result. We expect that these results will contribute to studies on exosomal surface protein markers for diagnosis of cancers.

Fourier‐transform Infrared (FT‐IR) spectroscopy fingerprints subpopulations of extracellular vesicles of different sizes and cellular origin

“…This drawback is often circumvented by coupling the analytes with plasmonic nanoparticles (SERS) [15,16], by labelling them with organic dyes (Raman reporters), or immune-labelling with nanoprobes [17]. These strategies allowed to distinguish EVs from various sources, disease contexts [18,19] and singlevesicle analysis [20][21][22]. SERS-active nanostructures can enhance the Raman signals of target molecules by several orders of magnitude, but can have problems in stability, poor reproducibility, and sample damaging according to their material composition and architecture [23,24].…”

An Expedient SERS Strip Tactic for Rapid On‐Site Detection with Long‐Time Sensitivity and Repeatability

“…Such algorithms mainly require good reproducibility and consistency between the labelled samples and the detected unknown samples and are relatively less influenced by the poetical chemical or physical change during the tests if the same change happens in both the labelled samples and the detected unknown samples. Herein, we applied the principle component analysis (PCA), which was frequently applied for the classification goals [29], to these spectra to attempt to cluster the spectra based on species. Overall, the first two components covered over 95% of the information of the original spectra, indicating the feasibility of the PCA method to these spectra.…”

Nanoplasmonic Approaches for Sensitive Detection and Molecular Characterization of Extracellular Vesicles

“…Cancerous exosome-specific protein markers are associated in terms of signal similarity. Reprinted with permission from Shin et al (2018) Copyright (2018) American Chemical Society.…”

“…In that study, a cationic AuNP coating further facilitated binding of anionic nEVs, and SERS spectra from lipid and proteins distinguished pancreatic cancer serum samples from healthy controls in most patients with sensitivity and specificity of 90.6 and 97.1%, respectively. Shin et al used antibody-coated 80 nm AuNPs in a similar fashion to detect characteristic SERS bands associated with nEV chemical content that distinguished NSCLC nEVs from healthy controls (Figure 13) (Shin et al, 2018). A more exotic SERS substrate was introduced by way of its strong plasmonic “gap-mode” (Sivashanmugan et al, 2017).…”