Developing slow-off dickkopf-1 aptamers for early-diagnosis of hepatocellular carcinoma

In this work, we obtained fast-off and slow-off aptamer recognizing dickkopf-1(DKK1), a promising biomarker for detection of early-stage hepatocellular carcinoma (HCC), with high affinity in a single SELEX procedure. The two types of aptamer possessed distinct characteristics confirmed via different validation methods. In comparison to fast-off aptamers, slow-off aptamers were proven more suitable for aptamer-based ELISA assay. Using slow dissociation SELEX, slow-off aptamers were selectively retained. Meanwhile, a mutant (34del) of slow-off D10 was estimated with picomolar affinity (371.9 pM). The mutant was further truncated into 39nt before pairing with an antibody in the aptamer-based ELISA. The aptamer-target-antibody construction showed similar performance as conventional ELISA with a detection limit of 62.5 pg/ml. Quantification in 60 sera samples with the construction was also correlated with conventional ELISA. The results demonstrated novel DKK1 aptamer could replace capture antibody for potential early HCC diagnosis.