SERS-based Nanoplasmonic Exosome Analysis: Enabling Liquid Biopsy for Cancer Diagnosis and Monitoring Progression

Exosomes, membrane-bound vesicles having a diameter of 30-150nm, are secreted by most cell types, including tumor cells. These vesicles mediate intercellular communication by transferring bioactive molecules (including a variety of proteins and nucleic acids) from donor to recipient cells. Notably, tumor cells secrete more exosome into microenvironment than nontumoral cells. Tumor-derived exosomes are enriched in molecular and genetic traits of tumor cells that facilitate cancer initiation, progression, and metastasis. Due to their abundance and stability, exosomes are one of the promising diagnostic and prognostic biomarkers for various cancers. Despite promising clinical potential, exosome-based diagnostics remains challenging because of the heterogeneity of exosome and difficulties in the profiling of exosomal contents. Therefore, there is a necessity to develop the sensing platform for molecular fingerprinting of exosomes toward clinical application. In this critical review, we explore the emerging use of nanoplasmonic biosensors to detect exosomal biomarkers and the application of this technology to the diagnosis and monitoring of cancer.