A novel electrochemical biosensor based on MIL-101-NH2 (Cr) combining target-responsive releasing and self-catalysis strategy for p53 detection

A novel electrochemical biosensor was constructed to detect p53 gene based on MIL-101-NH2 (Cr) by combining target-responsive releasing and self-catalysis strategy. MIL-101-NH2 (Cr) with suitable pore structure was used to encapsulate methylene blue (MB) as signal probe. The hairpin DNA (HP) containing rich-G sequences was used as gatekeeper to seal up the pores and avoid MB leakage through covalent immobilization. The p53 gene could hybridize with the loop portion of HP for the formation of dsDNA, which had the specific nicking site of the nicking endonuclease (Nt.BstNBI). Then Nt.BstNBI recognized the specific recognition site and cleaved HP to open the pore for releasing of MB. Meanwhile, the cleavage of HP released the target DNA to trigger the target recycling for signal amplification. More importantly, the plentiful rich-G sequences were exposed to form Hemin/G-quadruplex DNAzymes, which could unite MIL-101-NH2 (Cr) to catalyze redox reaction of MB released by itself for signal amplification. The biosensor for p53 had wide linear range from 1 × 10-14 to 1 × 10-7 M and a low detection limit of 1.4 × 10-15 M. The combination of target-responsive releasing and self-catalysis strategy provided a promising way for constructing ultrasensitive and simple biosensor.