In the past decade, the study of exosomes, nanosized vesicles (50-150 nm) released into the extracellular space via the fusion of multivesicular bodies with the plasma membrane, has burgeoned with impressive achievements in theranostics applications. These nanosized vesicles have emerged as key players in homeostasis and in the pathogenesis of diseases owing to the variety of the cargos they can carry, the nature of the molecules packaged inside the vesicles, and the robust interactions between exosomes and target cells or tissues. Accordingly, the development of exosome-based liquid biopsy techniques for early disease detection and for monitoring disease progression marks a new era of precision medicine in the 21st century. Moreover, exosomes possess intrinsic properties – a nanosized structure and unique “homing effects” – that make them outstanding drug delivery vehicles. In addition, targeted exosome-based drug delivery systems can be further optimized using active targeting ligands such as nucleic acid aptamers. Indeed, the aptamers themselves can function as therapeutic and/or diagnostic tools based on their attributes of unique target-binding and non-immunogenicity. Researchers at Deakin University provide a current picture of the research on exosomes and aptamers and their applications in cancer theranostics, highlighting recent advances in their transition from the bench to the clinic.
A scheme of exosome isolation and/or analysis via an electrochemical aptasensor
In this platform, the electrode is made of gold and carbon surfaces for the detection of different target analytes, e.g., tumor-derived exosomes of various sizes. Changes in the redox signal are proportional to the concentration of exosomes. After aptamer immobilization followed by incubation with exosomes, the signal is typically significantly suppressed due to the decreased electrode surface area.