MIP Nanoparticle-Based SPR Sensor for Diethyl Phthalate: Design, Characterization, and Analytical Applications

Phthalates (PAEs) are a group of chemicals widely used as plasticizers in various industrial and consumer products. Due to their extensive use and potentially harmful effects on human health, particularly as endocrine-disrupting compounds, the rapid and efficient detection of PAEs is crucial. Recent developments in sensor technology have significantly enhanced the monitoring of environmental and food contaminants. This study aimed to develop a surface plasmon resonance (SPR) sensor utilizing diethyl phthalate-imprinted nanoparticles (DEP-MINPs) for the sensitive and selective detection of DEP. DEP-MINPs were synthesized via microemulsion polymerization and immobilized onto a bare gold SPR chip as a recognition layer. The DEP-MINPs were characterized using FTIR, TEM, and zeta potential analyses. The kinetic performance was investigated within a concentration range of 1.0–135.0 μM, observing a strong linear correlation between DEP concentration and SPR sensor response. The calculated limit of detection was 0.30 μM. The Langmuir model best described the interaction, suggesting monolayer adsorption on a homogeneous surface. Selectivity studies using structurally similar compounds, including dimethyl phthalate, styrene, and vanillic acid, revealed that the sensor was 2.64, 5.00, and 4.83 times more selective for DEP, confirming the success of the molecular imprinting process. The developed SPR sensor was successfully used for DEP analysis in bottled water and sanitary pad samples. The DEP-MINPs SPR sensor demonstrated excellent reproducibility and stability over multiple measurements and days, supporting its potential for practical applications in environmental monitoring.