Attention on extracellular vesicle (EV) membrane biomarkers has increased exponentially in recent years. They offer a promising alternative as they have proven potential for novel biomedical applications. As EVs inherit and transport “cargo” molecules such as transmembrane proteins from their cells of origin, they can be used to assess whether a cell is healthy or diseased1.
Within our research group, a previous study had isolated and fully characterised EVs from exhaled breath condensate (EBC)2. The study also found that breath-derived EVs could be captured using an aptamer. Although mostly water, EBC contains particles and molecules from the lower respiratory tract - bronchioles and alveoli, providing a window to the particles residing therein. Thus, EVs in exhaled breath may provide a non-invasive approach to diagnose lung cancer at the early stage. This can complement current methods that are tedious and invasive. Moreover, early diagnosis is desired as symptoms of lung cancer seldom manifest until the disease is already at an advanced stage and can no longer be treated.
In this project, we devised a biosensor platform to capture EVs and biomarkers by immobilising aptamers on gold substrates3. Surface modifications prepare the gold surfaces to be used as sensing electrodes in electrochemical impedance spectroscopy measurements. Capture of EVs and biomarkers produced electrical signals that were monitored, yielding information about the character of the gold substrate and changes taking place. Monolayer optimisation proved to be crucial for platform performance. Successful adaptation could provide non-invasive early detection of lung cancer.