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Emerging evidence indicates that exosomes derived from gastric cancer cells enhance tumor migration and invasion through the modulation of the tumor microenvironment. However, it remains a major problem to detect cancer-specific exosomes due to technical and biological challenges. Most of the methods reported could not achieve efficient detection of tumor-derived exosomes in the background of normal exosomes. Herein, a label-free electrochemical aptasensor is presented for specific detection of gastric cancer exosomes. This platform contains an anti-CD63 antibody modified gold electrode and a gastric cancer exosome specific aptamer. The aptamer is linked to a primer sequence that is complementary to a G-quadruplex circular template. The presence of target exosomes could trigger rolling circle amplification and produce multiple G-quadruplex units. This horseradish peroxidase mimicking DNAzyme could catalyze the reduction of H2 O2 and generate electrochemical signals. This aptasensor exhibits high selectivity and sensitivity toward gastric cancer exosomes with a detection limit of 9.54 × 102 mL-1 and a linear response range from 4.8 × 103 to 4.8 × 106 exosomes per milliliter. Therefore, this electrochemical aptasensor is expected to become a useful tool for the early diagnosis of gastric cancer.
Huang et al. (Mon,) studied this question.