Rapid and Sensitive Gold Nanoparticles Based Colorimetric Sensor for Mn(II) Ions Detection: A Potential Approach for Urinary Health Monitoring

Abstract

Manganese (Mn) is an essential trace element, but excessive accumulation in the human body can cause severe neurotoxic effects, making sensitive monitoring in biological fluids such as urine important for public health. This study reports a rapid colorimetric sensor based on ethylenediaminetetraacetic acid (AuNPs-EDTA) for selective Mn(II) detection. AuNPs were synthesized by chemical reduction of HAuCl4 using NaBH4, producing spherical nanoparticles with a surface plasmon resonance (SPR) peak at 525 nm and a size of 20-40 nm. EDTA functionalization was confirmed by an SPR red shift to 535 nm, a zeta potential change from -32.34 to -45.68 mV, FTIR spectral shifts of carboxylate and hydroxyl groups, and retention of spherical morphology with a size of 25-40 nm. Upon addition of Mn(II), the AuNPs-EDTA suspension exhibited a concentration-dependent color change from wine red to blue accompanied by an LSPR shift from 535 to 670 nm. This sensor showed good linearity over 0.5-7.0 μg/L Mn(II) (R² = 0.9905), with a limit of detection (LOD) of 0.392 μg/L and a limit of quantification (LOQ) of 1.189 μg/L. High selectivity was obtained against common urinary ions and interferents, including Na+, K+, Ca²+, Mg²+, Zn²+, Cu²+, Pb²+, Cd²+, Co²+, Ni²+, Fe²+, Cl−, urea, uric acid, and creatinine. Recovery values of 94.46-98.01% (RSD < 2%) were achieved in spiked urine samples. These results demonstrate that AuNPs-EDTA provides a rapid, cost-effective, and promising platform for urinary Mn(II) monitoring.