Electrochemical detection of miRNA-100 in the sera of gastric cancer patients based on DSN-assisted amplification.

Gastric cancer (GC) is a common malignant digestive tract tumor that leads to high mortality worldwide. Early diagnosis of GC is very important for adequate treatment. However, a rapid, specific and sensitive method for the detection of GC is currently not available. Here, a biosensor CPs/AuNP-AuE, the gold nanoparticle (AuNP)-modified Au electrode (AuE) which was coupled with DNA capture probes (CPs), was developed to detect the content of miR-100 in the sera of GC patients. The results showed that AuNPs were uniformly deposited on the surface of AuE. AuNPs enhanced the electrical conductivity and improved the effective area of AuE. CPs were successfully assembled on AuNP-AuE that could be digested by duplex-specific nuclease (DSN) from the miR-100/CPs complex on the electrode, improving the sensitivity of the biosensor by recycling miR-100. The data revealed that the biosensor was highly specific for the detection of miR-100, which had the ability to distinguish one base-pair mistake in miR-100. The detection of the biosensor for miR-100 ranged from 100 aM to 10 pM and the limit of detection (LOD) was estimated to be 100 aM. The detection results of 100 human sera samples using this biosensor indicated that the cutoff for the detection of gastric cancer was 5 fM. Therefore the biosensor developed in our study served as a rapid, specific and sensitive strategy for the detection of gastric cancer in clinic.