A novel DNA sensor of homogeneous electrochemical signal amplification strategy

A simple homogeneous electrochemical biosensing platform was developed for efficient and ultrasensitive detection of K-rat sarcoma (K-ras) gene fragment via exonuclease III-assisted target recycling and pi-pi stacking between graphene and nucleotide bases. The presence of fully complementary target DNA, triggers the cycle of target DNA with the aid of exonuclease III (Exo III), resulting in short single strand DNA probe formation. Furthermore, a novel biferrocene was newly synthesized and used for probe labeling; the two ferrocene units provide a large electrochemical signal compared with single. The cyclic release biferrocene is adsorbed on graphene electrode due to DNA conformational change. Moreover, the method has a simple operation process, and is cost effective. Taking advantage of the unique surface property of graphene and high efficiency of DNA Exo III, our sensor shows good ability toward K-ras detection. The detection limit of 20.4 fM could be achieved possesses great potential in detect K-ras normal gene.