A novel signal-amplified electrochemical aptasensor based on supersandwich G-quadruplex DNAzyme for highly sensitive cancer cell detection

•A novel electrochemical biosensor for cancer cell detection was developed.•The aptamer–cancer cell interaction was transduced into DNA-based assay.•The sensitivity can be dramatically enhanced by supersandwich G-quadruplex DNAzyme.

A novel electrochemical biosensor for cancer cell detection was developed based on aptamer-based competition and supersandwich G-quadruplex DNAzyme amplification strategy. Due to the stronger affinity between the aptamer and cancer cells than that with its complementary oligonucleotide, the complementary oligonucleotide will be facilely replaced. As a consequence, we can detect cancer cells indirectly by detecting the releasing DNA which is proportional to the concentration of K562 cells. Through the supersandwich G-quadruplex DNAzyme amplification strategy, the sensitivity can be dramatically enhanced with detection limit down to 14 cells.