Sensitive and Rapid Detection of Glutamic Acid in Colloidal Solution by Surfactant Mediated Silver Nanoparticles

Abstract

A convenient and economical colorimetric chemo-sensor was developed for glutamic acid (Glu) detection in actual samples. The nanoscale sensor was synthesized by coating silver ions with sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The sensor, exhibited color change from yellow to pink when cross linked with Glu molecules and showed strong quenched in peak at 426 nm with the appearance of another absorption peak between 490 nm and 620 nm. The interaction mechanism of Glu and AOT-AgNPs was discussed with sophisticated analytical techniques i.e. Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Atomic force microscopy (AFM), and Dynamic light scattering (DLS). The results suggested that Glu interacted with the spheres of AOT-AgNPs through non-covalent bonding and electrostatic attractions of RNH3+ and COOH− groups, which caused time dependent complexation. In this manner, rapid method having detection and quantification limits of 1.64 µM and 4.98 µM in between 0.1 µM and 200 µM was achieved. Furthermore, this technique exhibited high selectivity toward Glu over a range of amino acids, biological relevant metal ions and molecules. Moreover, Glu molecules were effectively detected in physiological fluids with satisfactory recoveries in acceptable limit. Hence, this research offers an on-site colorimetric detection for Glu under easy operational conditions for vitro/non-invasive analyses.