Au@ZnNi-MOF labeled electrochemical aptasensor for detection of enrofloxacin based on AuPt@h-CeO2/MoS2 and DNAzyme-driven DNA walker triple amplification signal strategy

Abstract

Herein, an aptasensor based on Pb2+ dependent DNAzyme driven DNA Walker with the triple amplification signal strategy was developed for ultrasensitive detection of enrofloxacin (ENR). The composite of Au & Pt coated hollow cerium oxide (AuPt@h-CeO2), and polyethyleneimine (PEI) functionalized molybdenum disulfide (PEI-MoS2) were used as the substrate material to increase the specific surface area of the electrode and attach more DNA probes. In the presence of ENR, the aptamer can break away from the double-stranded structure, releasing DNAzyme capable of cleaving circular RNA with the help of Pb2+, which in turn will generate a large number of capture probes that bind the signal probes. In-situ reduced gold nanoparticles coated bimetallic metal-organic framework (Au@ZnNi-MOF) as signal labeled to catalyze thionine (Thi) to amplify the signal, which could be observed a significant electrochemical signal in square wave voltammetry (SWV). As expected, under the optimal conditions, the current in SWV is linearly related with the concentration of ENR in the range of 5.0 × 10−6 to 1.0 × 10−2 ng/mL with a limit of detection of 1.02 × 10−7 ng/mL. Further, it has been successfully used in real environmental water and milk samples and showed satisfactory performances.