Biomimetic Iron-Doped Polydopamine Sensor for Selective Detection of Polystyrene Nanoplastics

Abstract

Polystyrene (PS) nanoplastics have emerged as a significant environmental contaminant, posing risks to ecosystems and human health. Herein, a novel biomimetic electrochemical sensor has been developed for the sensitive and selective detection of PS nanoplastics, utilizing an iron-incorporated polydopamine (FePDA) matrix on a carbon paste electrode (CPE). Inspired by mussel adhesion proteins, the FePDA system mimics biological processes, combining strong adhesion, selective molecular interactions, and enhanced electron transfer properties. The FePDA/MCPE sensor demonstrated exceptional sensitivity, achieving a detection limit of 1 mg/L, facilitated by Fe³⁺/Fe²⁺ redox cycling that improves the electron transfer efficiency and reduces charge transfer resistance. Molecular docking simulations revealed strong π−π stacking interactions between PS nanoplastics and the FePDA matrix, contributing to high selectivity over other polymers such as polyethylene glycol and poly(vinyl alcohol). Electrochemical impedance spectroscopy measurements confirmed these findings, with a notable reduction in charge transfer resistance at the FePDA-modified electrode compared to the unmodified electrode. Validation experiments conducted with spiked tap water samples yielded 91 and 96% detection efficiencies, demonstrating the sensor’s applicability in real-world environmental monitoring scenarios. This biomimetic sensor provides a robust, portable platform for real-time, on-site detection of PS nanoplastics, addressing critical environmental monitoring and public health protection needs. A biomimetic electrochemical sensor enables the specific detection of PS nanoplastics, addressing their widespread environmental contamination and mitigating associated ecological and public health risks.