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Triple Helix Molecular Switch Cascade Multiple Signal Amplification Strategies for Ultrasensitive Chloramphenicol
Suping Deng1, Futing Wang2, Yujin Li2,3
1Hunan Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang421001, China.
Abstract:
A novel self-powered biosensor has been developed for the detection of chloramphenicol (CAP) based on difunctional triple helix molecular switch (THMS)-mediated DNA walkers. The biosensor utilizes the CAP aptamer as the recognition element, a DNA walker and capacitor as dual signal amplification strategies, and a digital multimeter (DMM) as the data readout equipment. In the presence of the target, the CAP aptamer in THMS specifically binds with CAP to release a signal transduction probe (STP) and opens the H1 hairpin structure in the biocathode to trigger the DNA walker and form a double-stranded DNA structure. Then, [Ru(NH3)6]3+ is electrostatically adsorbed on the double-stranded DNA structure through electrostatic adsorption and reduced to [Ru(NH3)6]2+ at the biocathode by accepting electrons entering at the bioanode. In DNA walkers, more double-stranded structures are formed, and a higher open-circuit voltage (EOCV) is observed. This self-powered biosensor with a detection limit (LOD) of 0.012 fM exhibits ultrasensitive CAP detection in milk in the range of 0.1-104 fM as well as excellent selectivity, stability, and reproducibility.
