Nanomechanical sandwich assay for multiple cancer biomarkers in breast cancer cell-derived exosomes.

The use of exosomes as cancer diagnostic biomarkers is technically limited by their size, heterogeneity and the need for extensive purification and labelling. We report the use of cantilever arrays for simultaneous detection of multiple exosomal surface-antigens with high sensitivity and selectivity. Exosomes from breast cancer were selectively identified by detecting over-expressed membrane-proteins CD24, CD63, and EGFR. Excellent selectivity however, was achieved when targeting the cell-surface proteoglycan, Glypican-1 at extraordinary limits (∼200 exosomes per mL, ∼0.1 pg mL(-1)).