RESUMO
We report an enzyme-free, sensitive strategy for DNA detections through fluorescence amplification. The sensing method employs molecular beacons (MBs) and two single-stranded helper DNA probes. In the presence of a DNA target, it binds and opens an MB. This triggers the hybridizations between the MB and helper probes, and consequently releases the DNA target, which becomes available to react with another MB and enhances the fluorescence emission of the MBs. The detection limit of the proposed strategy is 0.58 pM, which is about 3 orders of magnitude better than the conventional MB-based method. This method is also fast and exhibits good selectivity. It is superior to previous MB-based amplification approaches employing enzymes or nanomaterials.
Assuntos
DNA/análise , Técnicas de Amplificação de Ácido Nucleico/métodos , Técnicas Biossensoriais/economia , Técnicas Biossensoriais/métodos , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , DNA de Cadeia Simples/química , DNA de Cadeia Simples/genética , Fluorescência , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/economia , Espectrometria de Fluorescência/economia , Espectrometria de Fluorescência/métodosRESUMO
The comparative study on the electro-generation of H2O2 using an activated carbon fiber cathode and graphite cathode was investigated. The effect of the operating parameters on the H2O2 generation concentration and current efficiency, such as the initial pH, current density and electrolyte concentration, was also evaluated. The results revealed that the activated carbon fiber cathode was more effective compared to the graphite cathode. The maximum value of H2O2 concentration could be achieved with pH 3.00, current density 8.89 mA/cm2 and electrolyte concentration 0.05 mol/L. However, due to the formation of competitive electrode reactions, the current efficiency of this electrolysis system is lower than other electrolysis system. In addition, a new kinetic model was established to well describe the electro-generation of H2O2. The experimental data were fitted well using the kinetic model.
