State-of-the-Art Applications of Field-Effect Transistor Biosensors in Exosome Detection: A Comprehensive Review

Exosomes are a kind of nanoscale extracellular vesicle secreted by almost all cell types and considered promising biomarkers for disease diagnosis since they could carry abundant proteins, nucleic acids, and lipids that reflect parental cell states. However, conventional exosome detection methods suffer from several limitations including insufficient specificity, low throughput, high costs, and inadequate sensitivity for clinical applications. By contrast, field-effect transistor (FET) biosensors are a promising alternative by enabling label-free, real-time, and ultrasensitive detection of exosomes through direct transduction of biorecognition events into electrical signals. This review first introduces the fundamental principles and device structure of FET biosensors, as well as exosome isolation strategies. The recent advances in exosome analysis using FET-based biosensors are then presented, which are categorized into two primary strategies: (1) direct detection of intact exosomes based on surface markers, including tetraspanin proteins (CD9, CD63, CD81, etc.) and disease-specific biomarkers, and (2) detection of exosomal contents including microRNA and protein biomarkers following exosome lysis. Finally, we discuss current challenges of FET-based exosome detection and provide perspectives on future developments.