Biosensor-based methods for exosome detection with applications to disease diagnosis

Exosomes are nanoscale extracellular vesicles (EVs) secreted by most eukaryotic cells and can be found in nearly all human body fluids. Increasing evidence has revealed their pivotal roles in intercellular communication, and their active participation in myriad physiological and pathological activities. Exosomes' functions rely on their contents that are closely correlated with the biological characteristics of parental cells, which may provide a rich resource of molecular information for accurate and detailed diagnosis of a diverse array of diseases, such as differential diagnosis of Alzheimer's disease, early detection and subtyping of various tumors. As a category of sensitive detection devices, biosensors can fully reveal the molecular information and convert them into actionable clinical information. In this review, recent advances in biosensor-based methods for the detection of exosomes are summarized. We have described the fabrication of various biosensors based on the analysis of exosomal proteins, RNAs or glycans for accurate diagnosis, with respect to their elaborate recognition designs, signal amplification strategies, sensing properties, as well as their application potential. The challenges along with corresponding technologies in the future development and clinical translation of these biosensors are also discussed.