Liquid biopsy has significant advantages over traditional tumor biopsies, because it is minimally invasive and uses biofluids, such as blood and urine, to diagnose cancer and other diseases in their early stages. Exosomes, which are actively secreted from cancer cells, carry molecular constituents of their originating cells. Because these membranous extracellular vesicles can serve as cellular surrogates, exosomes have emerged as a new type of potent biomarkers. However, conventional exosome analysis methods such as immunoblotting or enzyme-linked immunosorbent assays are costly and require approximately twelve hours and excessive volumes of serum to detect transmembrane proteins on the surface of exosomes. Exosome separation requires complex steps to remove debris or cellular components that will confound downstream analysis. High-throughput molecular profiling of exosomes using miniature label-free biosensors is not available. The goal of this project is to develop a new capability to rapidly screen and profile exosomes based on both molecular and size characteristics. This research will lead to a transformative change in exosome analysis by integrating two state-of-the-art technologies on a single silicon chip. In addition, this research will be integrated with education through adding new lab modules to existing undergraduate biomedical engineering minor program curriculum, recruiting female students, and providing summer internship opportunities to African-American students to participate in the project at Iowa State University, and developing a new undergraduate-level course related to nanobiotechnology at Arizona State University.
The project will lead to an integrated silicon-based nano-opto-fluidic platform for rapidly and continuously profiling of both molecular and size features of exosomes. Cascaded nanoscale deterministic lateral displacement pillar arrays will be developed to simplify the isolation and size profiling of exosomes. The exosomes will be effectively separated from interference molecules present in the fluid sample. High-performance lateral flow-through optical biosensors will be developed to quantify the separated exosomes. The exosome samples can flow through the nanoscale biosensor and be immobilized and enriched on the functionalized sensor surface. Because both the separation and detection modules have the features of lateral flow designs, they can be integrated on a single silicon chip using the nanoimprint lithography process. The integration of these two functions will lead to an unprecedented ability to continuously streamline exosome separation, enrichment and detection processes to profile multi-dimensional molecular and size information for multiple protein markers within one hour. The biological validation plan of the project will be carried out using the proposed device to sort and sense exosomes released from a parasitic nematode and etiological agent of the human disease, Lymphatic Filariasis. The proposed technology is advantageous over the lab-based methods in terms of cost, sample consumption, and throughput, and could be extended to the profiling of circulating exocellular exosomes in human or animal biofluids to diagnose a variety of diseases, identify companion biomarkers that are important for drug discovery, and monitor the progress of a therapy.