Examples of Raman scattering techniques for exosome detection and quantification. The figure permissions are as follows: (A) license number 5071621135225, license date May 17, 2021, licensed content publisher John Wiley and Sons. Licensed content publication of “Quantitative and Specific Detection of Exosomal miRNAs for Accurate Diagnosis of Breast Cancer Using a Surface-Enhanced Raman Scattering Sensor Based on Plasmonic Head-Flocked Gold Nanopillars”. (B) Adapted with permission from Pramanik, A. et al. 2020. Mixed-dimensional heterostructure material-based SERS for trace level identification of breast cancer-derived exosomes. ACS omega, 5(27), pp. 16602–16611. Copyright (2021), hps://pubs.acs.org/doi/10.1021/acsomega.0c01441, and further permissions related to the excerpted material should be directed to ACS. (C) Adapted from Smith, Z.J. et al. 2015. Single exosome study reveals subpopulations distributed among cell lines with variability related to membrane content. Journal of extracellular vesicles, 4(1), p. 28533. The work was made available under the Creative Commons CC0 public domain dedication 10/2021 (http://creativecommons.org/licenses/by-nc/4.0/). (D) License number 5071700114394, license date 17 May 2021, licensed content publisher Elsevier. Licensed content publication of “Quantitative detection of exosomal microRNA extracted from human blood based on surface-enhanced Raman scattering”.