Advances of surface-enhanced Raman spectroscopy in exosomal biomarkers analysis

Cancer derived exosomal biomarkers (e.g. proteins, RNAs) could reflect important information about the cancer microenvironment. For ultrasensitive analysis of exosomal biomarkers, surface-enhanced Raman scattering (SERS) is one of the primary methods. Regarding the specific requirement of exosomal analysis, we firstly summarized the SERS substrates from zero-dimensional (0D) colloidal substrates to 2D planar substrates, and 3D stereoscopic substrates in the past five years. In terms of exosomal biomarkers analysis, we systematically subdivided label-free and label-aid SERS analysis into exosome, exosomal protein, and exosomal miRNA detection, according to the actual detection targets. Ultimately, we made a brief summary of the overview and look forward to the forthcoming directions of SERS-based exosomal analysis. This review will attract researchers who dedicated to analysis of cancer derived exosomal biomarkers via SERS, and shed light on the important status of exosomes in the early diagnosis of cancer.