Self-Assembly and Disassembly of Membrane Curvature-Sensing Peptide-Based Deep-Red Fluorescent Probe for Highly Sensitive Sensing of Exosomes

With increasing knowledge of the diverse roles of exosomes in biological processes, much attention has been paid to the development of analytical methods for exosome analysis. Here, we developed a new class of amphipathic helical (AH) peptide-based fluorescent probes for highly sensitive detection of exosomes in a mix and read manner. Membrane curvature-sensing AH peptide (ApoC) was coupled with lipophilic tail (C12)-carrying thiazole red (TR) for construction of a self-assembly/disassembly based fluorescence "off-on" sensing system for target exosomes. ApoC-TR_C12 has extremely weak emission due to the formation of the aggregates, whereas it becomes emissive in response to the target exosomes through the binding-induced disassembly of ApoC-TR_C12. We demonstrated that the C12 unit attached to the TR unit had a favorable effect on both fluorescence response (signal-to-background: S/B) and binding affinity. ApoC-TR_C12 was applicable to rapid and simple detection of exosomes with high detection sensitivity (limit of detection ≈ 10³ particles/μL).