A facile homogeneous electrochemical biosensing strategy based on displacement reaction for intracellular and...

Traditional electrochemical hydrogen peroxide (H₂O₂) assays all indispensably require the immobilization of enzyme or nanomaterials on electrode surface. These complex electrode surface modifications are laborious and time-consuming. To overcome such limitations, we developed here a facile homogeneous electrochemical biosensor based on displacement reaction for detection of intracellular and extracellular H₂O₂ produced by living cells. Methylene blue-labeled short single-stranded DNA strand (DNA-MB) was ingeniously designed as the reporter, which was adsorbed on CeO₂ nanoparticles to result in low electrochemical signal. In the presence of H₂O₂, DNA-MB was released from CeO₂ nanoparticles, leading to the significant enhancement of current signal. Therefore, a simple homogeneous electrochemical H₂O₂ assay is successfully achieved. This strategy also displays excellent anti-interference capability and reproducibility for H₂O₂ determination. More importantly, this method was capable of conveniently realizing intracellular and extracellular H₂O₂ assay. Thus, with the excellent merits of simplicity, rapidness, good repeatability, high specific and sensitivity, the proposed strategy has great potential to be applied in exploring the roles of H₂O₂ in physiological and pathological processes.