A sensitive colorimetric sensor for methamphetamine detection based on the peroxidase-like activity of Fe3O4-VB2@CeO2 nanozyme

A Fe 3 O 4 -VB 2 @CeO 2 ternary nanozyme was designed for METH detection. • Selective recognition of METH over HER/MOR via –NH and electrostatic attraction. • The sensor shows a low LOD of 3.4 ng mL −1 and a wide linear range. • It enables on-site colorimetric detection in serum with good specificity. Selective detection of methamphetamine (METH) over other illicit drugs is essential for forensic analysis and clinical screening, yet conventional methods are expensive, complex, and unsuited for on-site use. Herein, we developed a colorimetric platform based on a Fe 3 O 4 -VB 2 @CeO 2 ternary composite nanozyme for specific METH recognition. The nanozyme was synthesized via a two-step solvothermal method, where Fe 3 O 4 acts as the magnetic core, riboflavin (VB 2 ) serves as an electron mediator, and CeO 2 provides abundant catalytic active sites. Mechanistic studies (FT-IR, XPS, Zeta potential) suggest that METH is adsorbed onto the nanozyme surface through a combination of electrostatic interactions and other non-covalent forces, potentially including hydrogen bonding and π–π stacking interactions. This adsorption appears to modulate the surface chemistry and interfacial electron transfer dynamics, which may contribute to the suppressed generation of hydroxyl radicals (·OH) and the reduced peroxidase (POD)-like activity of the nanozyme. Under optimized conditions, the colorimetric signal shows an excellent linear relationship with the logarithm of METH concentration from 0.005 to 12 μg/mL, with a detection limit of 3.4 ng/mL. The sensor exhibits high specificity for METH, with negligible response to heroin (HER) or morphine (MOR), and shows negligible interference from various metal ions, amino acids, metabolites, and serum components. This work presents a visual strategy for on-site rapid METH detection and offers a plausible mechanistic interpretation of nanozyme inhibition based on indirect evidence. Download: Download high-res image (339KB) Download: Download full-size image