CTAB assisted electrochemically synthesized zinc-based metal-organic framework film for rapid detection of polystyrene nanoplastics

A cetyltrimethylammonium bromide (CTAB)-modified zinc-based metal-organic framework (Zn-MOF) was developed for rapid detection of nanoplastics in aqueous environments. The Zn-MOF-CTAB was synthesized via an electrochemical in-situ method under ambient temperature and pressure conditions. To enhance nanoplastics capture, the organic ligand aminoterephthalic acid was incorporated to impart positive charges to the Zn-MOF within a wide pH range, while the cationic surfactant CTAB introduced hydrophobic groups, synergistically boosting the material’s adsorption capacity for aqueous nanoplastics. The MOF exhibited inherent electrochemical activity from the Zn(II)/Zn(I) redox couple, measured via linear sweep voltammetry (LSV). The peak current of this redox process decreased quantitatively upon nanoplastics adsorption. This current suppression was used as the direct detection signal for quantifying nanoplastic concentrations. For polystyrene (PS) nanoplastics (100 nm, 500 nm, 1 μm), the sensor achieved a low detection limit of 0.1 μg/mL. Furthermore, the practical applicability of this electrochemical sensing platform was validated in real water samples.