Exosomes are phospholipid nanovesicles secreted by mammalian cells that have recently been a topic of interest in cancer research and reports. These miniscule particles are released in large numbers by most types of cancers and often carry molecular information about the parent tumor cell: information that could be useful in diagnostic and tumor response to therapy situations. However, current methods of exosome analysis tend to be difficult to use in clinical settings where exosome concentration is low, or that require high throughput. A group of researchers at the Center for Systems Biology at Massachusetts General Hospital has recently developed a surface plasmon resonance (SPR) assay based on optical transmission through periodic nanoholes called the nano-plasmonic exosome (nPLEX) assay. This generation of the nPLEX sensor was designed for label-free detection of exosomes and validated across different ovarian cancer cell lines and ascites samples from ovarian cancer patients. A next generation nPLEX sensor is being created with the goal of establishing and validating the clinical utility of the sensor across a wide range of human cancers including glioblastoma multiforme, pancreatic, and ovarian cancer.
One of the critical components in proteomic research, including exosome studies, is selecting the correct antibodies and validating their qualities in a high-throughput way. The affinity, specificity, reproducibility, and selectivity of antibodies tend to have some variation by many factors including vendor, clonality, target epitopes, species, and storage condition. Using microarray spotting technology, a protocol on high-throughput antibody validation will be established for nPLEX. Specifically, different antibodies (e.g. antibodies for CD63, a well known exosome surface marker) will be conjugated on the nPLEX chip using the microarray spotting system; antibodies will then be tested through exosome interactions. The antibody validation protocol is expected to reduce assay development costs and improve the accuracy of the nPLEX assays.
The nPLEX chip loaded into the microarray spotting system. This technique allows for antibody conjugation on the nPLEX for exosome interaction testing.