Highly efficient quenching of electrochemiluminescence from CdS nanocrystal film based on biocatalytic deposition

Aiming to find an alternative electrochemiluminescence (ECL) quenching route of high efficiency, biocatalytic precipitation (BCP) was firstly coupled with ECL for investigating its insulating effect on ECL. Experimental data revealed that an insulating layer could be formed via BCP onto the electrode surface, inhibiting the reaction between the coreactant and luminophore and thereby impairing the ECL emission dramatically. Since the extent of insulating effect associated strongly with analyte concentration, a new ECL biosensor was successfully realized. In a model horseradish peroxidase (HRP)-based system, the fabricated biosensor possessed high sensitivity and wide linear range from 1.0 × 10−10 M to 1.0 × 10−6 M for H2O2 determination with a detection limit of 4 × 10−11 M (S/N = 3). This method has great potential in extending the application of ECL biosensor for various bioanalytes.