Metastasis are responsible for more than 90% of cancer-associated mortality; thus the clinical need for early metastasis detection is high. Exosomes are small membrane vesicles (50-150nm) which contain membrane-associated proteins and RNA which mirrors the cell of origin. Recent studies show that exosomes serve communication between the primary tumor and the metastasis. Viewing cancer within the context of ecosystems may provide opportunities to exploit exosomes as diagnostic agents. The current methods for exosomes isolation are insufficient. They mostly copurify protein aggregates and the protocols are not reproducible. The final aim of this project is to develop nanobody-based immunoaffinity capture protocols to purify exosomes from plasma. These protocols will distinguish normal exosomes from cancer exosomes, and mRNA sequencing will allow the identification of disease-specific signatures. Recombinant nanobodies have a reduced mass, are easily engineered, are stable and easily to produce. Furhtermore, panning pre-immune phage display libraries do not need animals, avoiding ethical concerns.