Homogeneous electrochemical protein assay based on repeated DNA hairpin self-folding and catalyzed extension

As a significant functional protein in maintaining genomic stability, flap endonuclease 1 (FEN1) is widely recognized as a promising disease biomarker and a druggable target for therapy. We herein fabricate a novel homogeneous electrochemical method for FEN1 assay based on highly efficient self-priming amplification strategy. A screen-printed electrode is first prepared coupling reaction and detection chambers with a microchannel for solution transportation. A single dumbbell structured probe is designed to respond to target FEN1, which undergoes repeated DNA hairpin self-folding, catalyzed extension and concatemer formation processes. The obtained product offers remarkable electrochemical response by intercalating electrochemical species. This homogeneous electrochemical method exhibits a limit of detection as low as 0.0114 mU. The high specificity for FEN1 is validated by comparing with other interfering proteins. It is also successfully used for the analysis of inhibitors, cells samples and clinical samples. These satisfactory results suggest that it may provide a promising sensing platform for the applications of biomedical research, clinical diagnosis and drug screening.