Glutathione and Magnetic Nanoparticle-Modified Nanochannels for the Detection of Cadmium (II) in Cereal Grains

We developed a novel and portable magnetic nanochannel electrochemical sensor for the sensitive detection of cadmium ions (Cd2+), which pose serious risks to food safety and human health. The sensor was fabricated by co-modifying an anodic aluminum oxide (AAO) nanochannel membrane with a composite of glutathione (GSH) and ferric oxide nanoparticles (Fe3O4), denoted as GSH@Fe3O4. This modified membrane was then integrated with a screen-printed carbon electrode (SPCE) to construct the GSH@Fe3O4/GSH@AAO/SPCE sensing platform. The performance of the sensor was evaluated using differential pulse voltammetry (DPV), which demonstrated a strong linear correlation between the peak current response and the concentration of Cd2+ in the range of 5–120 μg/L. The calibration equation was IDPV(μA) = −0.31 + 0.98·CCd2+(μg/L), with an excellent correlation coefficient (R2 = 0.999, n = 3). The calculated limit of detection (LOD) was as low as 0.1 μg/L, indicating the high sensitivity of the system. These results confirm the successful construction of the GSH@Fe3O4/GSH@AAO/SPCE portable nanochannel sensor. This innovative sensing platform provides a rapid, sensitive, and user-friendly approach for the on-site monitoring of heavy metal contamination in agricultural products, especially grains.