CRISPR/Cas12a-based electrochemical aptasensor for determination of breast cancer-derived exosomes

Tumor-derived exosomes take an important role in the onset and progression of cancer and are promising biomarkers for early tumor diagnosis. However, detecting exosomes with ultra-sensitivity and high specific still remains a challenge. Herein, we developed an ultra-sensitivity and simple electrochemical method based on the subtly combination of CRISPR/Cas12a, aptamer and magnetic nanoparticles (MNPs) for the determination of breast cancer (BC)-derived exosomes. The complex of the aptamer and its partially complementary DNA (probe 1, P1) were conjugated to magnetic nanoparticles. In the presence of the exosome, the surface proteins of exosomes can specifically bind with the aptamer resulting in the release of P1. The freed P1 combines with crRNA, triggering the trans-cleavage activity of CRISPR/Cas12a, leading to the methylene blue labeled singlestranded DNA reporter (probe 2, P2) modified on the gold electrode being cut. Benefiting from the outstanding trans-cleavage activity of Cas12a, the high specific binding between the target and aptamer, and the excellent separation ability of the MNPs, our platform achieved an ultrasensitive and highly specific detection of exosomes with the limit of detection as low as 280 particles/mL. In addition, our platform has demonstrated the capability to accurately discriminate the healthy individuals from breast cancer patients, thereby expanding the avenues and insights of exosomes detection and providing a novel and attractive tool for early diagnosis BC.