Electrochemically enhanced peroxidase-like activity of nanohybrids for rapid and sensitive detection of H2O2 and Dopamine

Longer detection times and low sensitivities are the two main drawbacks of applying colorimetric detection methods in field applications where rapid and sensitive detection is required. A discovery of the enhancement of nanozymatic activity via electrochemical means which significantly reduces the analyte detection time and enables ultra-low detection levels has been reported in this paper. A novel, simple and facile approach for the synthesis of carbon quantum dot-gold nanoparticles (CQD-AuNPs) has been developed. The CQD-AuNPs showcased catalytic activity through the oxidation of 3,3′,5,5′-Tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) and followed the characteristic Michaelis-Menten equation. Surprisingly, the catalytic activity of CQD-AuNPs nanohybrids enhanced considerably while the reaction was completed under an electrochemical process and assisted the detection of H2O2 and Dopamine (DA) with a limit of detection (LOD) value of 240 nM, and 0.75 μM, respectively. Most importantly, the detection time decreased by 60-fold compared to conventional nanozymatic reactions. The work covered in this paper provides a novel approach to develop the nanocomposite and a new detection technique that can be utilized across various fields of science and engineering to improve and exploit enzymatically dependent reactions.