Optical biosensors for detection of exosomes

Exosomes, nanoscale extracellular vesicles secreted by various cell types, have emerged as critical mediators of intercellular communication and valuable indicators of physiological and pathological states. Their stable presence in biofluids and ability to carry disease-specific molecular cargo make them ideal candidates for non-invasive diagnostics. Traditional exosome isolation and detection techniques, while foundational, often exhibit limitations in sensitivity, specificity, and scalability. In response, optical biosensors have gained increasing attention due to their rapid response, high sensitivity, and compatibility with miniaturized analytical systems. This review presents a comprehensive overview of recent advancements in optical biosensor technologies developed for exosome detection. It explores various sensing modalities, including fluorescence, surface plasmon resonance (SPR), colorimetric, and surface-enhanced Raman scattering (SERS), and emphasizes how the incorporation of nanomaterials and engineered recognition elements has substantially improved detection performance. This review examines the biological significance and diagnostic potential of exosomes and explores recent progress in optical biosensing technologies, with particular emphasis on advances in sensor architecture, signal enhancement techniques, and the use of functional nanomaterials to improve analytical performance.