Current methods for the early diagnosis of cancer can be invasive and costly. In recent years, exosomes have been recognized as potential biomarkers for cancer diagnostics. The common methods for quantitative detection of exosomes, such as nanoparticle tracking analysis (NTA) and flow cytometry, rely on large-scale instruments and complex operation, with results not specific for cancer. Researchers at Central South University have developed a tri-channel electrochemical immunobiosensor for enzyme-free and label-free detecting carcino-embryonic antigen (CEA), neuron-specific enolase (NSE), and cytokeratin 19 fragments (Cyfra21-1) from exosomes for specific early diagnosis of lung cancer. The electrochemical immunobiosensor showed good selectivity and stability. Under optimum experimental conditions, the linear ranges were from 10−3 to 10 ng/mL for CEA, 10−4 to 102 ng/mL for NSE, and 10−3 to 102 ng/mL for Cyfra21-1, and a detection limit down to 10−4 ng/mL was achieved. Furthermore, the researchers performed exosome analysis in three kinds of lung cancer. The results showed a distinct expression level of exosomal markers in different types. These works provide insight into a promising alternative for the quantification of exosomal markers in specific diseases in the following clinical bioassays.
Schematic representation of the designed immunosensor for exosome biomarkers detection
(a) Principle of silanization process by APTES and aldehyde‐ammonia condensation by glutaraldehyde on the hydroxyled working electrode, (b) Schematic illustration of antibody, (c) Fabrication procedures of the electrochemical immunosensor, (d) Principle of differential pulse voltammetry for the detection of exosomes.