Exosomal analysis: Advances in biosensor technology.

Exosomes, a subtype of extracellular vesicle secreted by cells, have been a subject of intense research interest. Unfortunately, a simple and reliable method to separate exosomes has yet to be developed. As can be expected, the lack of a standardized method for extraction and purification has contributed to suboptimal inter-laboratory correlation and difficulty in comparison studies. Traditional techniques such as centrifugation, immunoaffinity and size exclusion chromatography, suffer from low purity and tend to be labor intensive thus making their use limited. To mitigate these drawbacks, an integrated biosensor-based exosome separation and detection has recently been developed. In this review, we examine five biosensors that use a variety of detection technology (colorimetric, fluorescent, surface plasmon resonance, surface-enhanced Raman scattering and electrochemical) and propose thoughts on standardization of exosomal analysis.