Multi-signal amplification electrochemical DNA biosensor based on exonuclease III and tetraferrocene
Homogeneous electrochemical DNA biosensor’s unique qualities has been of great interest to researchers, mainly due to its high recognition efficiency in solutions. However, the process of introducing additional markers and extra operations to obtain a signal are tedious and time consuming, which limits their overall potential applications. Herein, a novel tetraferrocene was synthesized and used as homogeneous electrochemical DNA biosensor probe label. It contains four ferrocene units that provide a greater signaling potential compared to monoferrocene, Furthermore, the target DNA triggers the cycle of double hairpin DNA probe with the aid of exonuclease III, promoting short single stranded DNA probe formation. The combination of the incorporated tetraferrocene labeled short DNA probe strands and graphene’s ability to adsorption single stranded DNA, the hybridization process can transform in an electrode signal provided by tetraferrocene. A low detection limit of 8.2 fM toward target DNA with excellent selectivity was achieved. The proposed sensing system avoids tedious and time-consuming steps of DNA modification, making the experimental processes simpler and convenient. The advantages of high sensitivity, selectivity and simple operation, makes this strategy applicable to DNA detection.