Molecular screening of cancer-derived exosomes by surface plasmon resonance spectroscopy

We report on a generic method to detect and iden- tify the molecular profile of exosomes either derived from cultured cell lines or isolated from biofluids. Exosomes are nanovesicles shed by cells into their microenvironment and carry the molecular identity of their mother cells. These vesi- cles are actively involved in intercellular communication un- der physiological conditions and ultimately in the spread of various diseases such as cancer. As they are accessible in most biofluids (e.g., blood, urine, or saliva), these biological entities are promising tools for cancer diagnostics, offering a non- invasive and remote access to the molecular state of the dis- ease. The composition of exosomes derived from cancer cells depends on the sort and state of the tumor, requiring a screen- ing of multiple antigens to fully characterize the disease. Here, we exploited the capacity of surface plasmon resonance bio- sensing to detect simultaneously multiple exosomal and can- cer biomarkers on exosomes derived from breast cancer cells. We developed an immunosensor surface which provides efficient and specific capture of exosomes, together with their identification through their distinct molecular profiles. The successful analysis of blood samples demonstrated the suit- ability of our bioanalytical procedure for clinical use