DFT theoretical study and experimental verification for sensitive detection of baicalein based on Bi2MoO6/GO composites

Baicalein (BAI), exhibits diverse pharmacological activities, making its accurate and sensitive detection crucial for clinical and pharmaceutical applications. To address the need for highly sensitive and precise detection of BAI, a novel composite electrochemical sensor Bi 2 MoO 6 /GO/GCE was developed. The electrochemical analysis revealed a synergistic interplay between the catalytic properties of Bi 2 MoO 6 and the exceptional conductivity of graphene oxide (GO), resulting in the sensor exhibiting remarkable sensitivity (1.27 μA μM −1 ) and a low detection limit (0.05 μM) within the BAI concentration range of 0.1–10 μM. Mechanistic investigations demonstrated that BAI undergoes a two-electron, two-proton oxidation process at 0.2 V (vs. SCE, saturated calomel electrode). Kinetic assessments confirmed that the electrode process is governed by a combined diffusion/adsorption mechanism. Notably, Density Functional Theory (DFT) calculations revealed that neutral BAI molecules (HA state) exhibit the highest adsorption energy (E ads = −4.01 eV) and the most substantial charge transfer (Δq = 1.29 e) on the Bi 2 MoO 6 surface, offering a molecular-level rationale for the observed optimal catalytic activity at pH 6.0. The sensor demonstrated outstanding reproducibility, long-term stability (signal decay < 3% over 15 days) and successful quantification in human serum samples. This study offers a robust sensing platform for monitoring drug metabolism through an integrated materials-performance-mechanism approach.