Cu2S/AFCNTs-based MIP sensors: voltammetric mechanism for sensitive BPA detection in milk

An electrochemical molecularly imprinted polymer (MIP) sensor is developed for sensitive detection of bisphenol A (BPA) based on leaf-like Cu 2 S/activated functionalized carbon nanotubes (AFCNTs) nanocomposite as the conductive substrate. The Cu 2 S/AFCNTs composite shows a BET specific surface area of 24.7 m 2 g − 1 , which is approximately eight times higher than that of the pure Cu 2 S (3.3 m 2 g − 1 ). This enlarged surface area contributes to abundant accessible active sites and promotes efficient electron transfer. The electroactive area of the Cu 2 S/AFCNTs-modified electrode is 0.40 cm 2 which is fivefold higher than the bare electrode (0.08 cm 2 ). The MIP film is electropolymerized onto the composite surface with a thickness of 2.91 nm. Mechanistic studies confirm that BPA oxidation is an adsorption-controlled irreversible process involving 2H + /2e − . Under optimized conditions, the sensor displays a broad linear range from 0.9 to 20 µM and a limit of detection of 0.19 µM with high selectivity against common interferents. The sensor also demonstrates good reproducibility (RSD 4.2%) and stability. Practical applicability is validated by determination of BPA in milk samples, with recoveries ranging from 99% to 102.1% (RSD 2.1 ~ 3.7%). This work highlights the synergistic enhancement of Cu 2 S and AFCNTs for constructing high-performance MIP-based electrochemical sensors for food safety monitoring.