Simple aminophenol-based electrochemical probes for non-enzymatic, dual amperometric detection of NADH and hydrogen...

Non enzymatic detection of NADH and H₂O₂ is of practical significance for both environmental and biological prospective. However, there is no simple, straight forward electrochemical sensor available for sensing of them in real samples. Addressing this challenge, we report a simple stimuli responsive aminophenol, pre-anodized screen printed carbon electrode (SPCE*/AP) based electrochemical probes for dual detection of NADH and H₂O₂. Aminophenol prepared and adsorbed on the electrode from aminophenylboronic acid via boronic acid deprotection with H₂O₂. The SPCE*/AP fabricated with this process was characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), Raman spectroscopy, UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). Amperometric detection results showed that SPCE*/AP electrodes exhibited linearity from 50 µM to 500 µM and from 200 µM to 2 mM with a detection limit (S/N = 3) of 4.2 µM and 28.9 µM for NADH and H₂O₂, respectively. Excellent reproducibility and selectivity for NADH and H₂O₂ were observed for this electrochemical platform. In addition, the matrix effect was investigated further using the same technique to analyze NADH and H₂O₂ in human urine samples, human serum samples, cell culture medium (containing 10% fetal bovine serum, FBS), and environmental water samples (tap water and rain water). Also, the present sensor demonstrated promising outcomes with living cells (normal cells and cancer cells).