Aptamer-based biosensing detection for exosomes: From selection to aptasensors

Exosomes reflect their source cells' phenotypic state, making them key biomarkers for tumors, cardiovascular diseases, neurodegenerative diseases, and immune responses. Therefore, detecting exosomes opens up new possibilities for disease prevention and treatment by improving patient survival and avoiding the risk of overdiagnosis and overtreatment. Among all available detection methods, aptasensors have the advantages of high sensitivity, significant selectivity, cost-effectiveness, stability, simple operation, and high detection throughput, which promote their wide application in biosensing. In this review, we provide a comprehensive summary of the recent advances in detecting exosomes using aptasensors. First, the current screening techniques and strategies for exosome-specific aptamers are explored, and guidance on selecting the appropriate strategy for generating aptamers with the optimal performance for exosome recognition is offered. Moreover, we introduce six main detector types used in aptasensors including electrochemical, fluorescent, colorimetric, surface plasmon resonance, surface-enhanced Raman scattering, and dual-mode. Based on these, the novel sensing material and mechanism, construction method, recognition mechanism, detection performance, and existing problems for aptasensors are systematically introduced. Finally, we explore the potential applications of aptasensors in exosome isolation, detection, and identification. We propose possible directions and address the challenges to harness the full potential of aptasensors in this field.