Integrated nanophotonic imaging and spectroscopy technology for scalable, purification-free, multi-parametric single exosome analysis

About This Grant

PROJECT SUMMARY Exosomes are nanoscale extracellular vesicles (30–150 nm in diameter) secreted by nearly all cell types into biological fluids such as blood, urine, saliva, and cerebrospinal fluid. Exosomes are known to play important roles in a variety of basic science and applied research fields such as cancer biology, neurological disorders, regenerative medicine, and dermatology. Exosomes are also heavily pursued for various diagnostic and therapeutic applications such as liquid biopsy and drug delivery. Current methods of analyzing exosomes have many limitations such as inadequate sensitivity and specificity, insufficient resolution for single exosome profiling, demanding sample volume, and heavily reliant on DNA amplification and sequencing techniques. In addition, most existing exosome pre-analytical sample preparation protocols require a multitude of steps involving purification, isolation, concentrating, and sophisticated labeling. These barriers have hampered the advances in exosome-centric basic and applied research and technology development. To address such an unmet need, the PI proposes to develop an Integrated Nanophotonic imaging and Spectroscopy Technology (INSPECT) for scalable, multi-parametric Single Exosome Analysis (SEA). The core is a nanophotonic chip to enable multi-modal imaging and spectroscopy based on three well-known nanoplasmonic enhancing mechanisms demonstrated in PI’s previous works: localized surface plasmon resonance (LSPR), plasmon- enhanced fluorescence (PEF), and surface-enhanced Raman scattering (SERS). These three techniques are highly complementary and can provide strong synergy in acquiring structural as well as compositional/molecular information from individual exosomes. Using LSPR-imaging, the PI has demonstrated individual exosomes can be detected, counted, and sized with 20 µL of undiluted and unpurified blood plasma. The same exosome population can then be interrogated by PEF using various fluorophore-labeled antibodies and molecular beacons to reveal exosomal surface and intravesicular molecular targets such as proteins and microRNAs. SERS will then provide a comprehensive, “non-targeting” molecular fingerprint.