Experimental and theoretical investigations for selective colorimetric recognition and determination of arginine and histidine in vegetable and fruit samples using bare-AgNPs

Abstract

We demonstrate the use of bare silver nanoparticles (AgNPs) as a nanoprobe for selective recognition and determination of arginine (Arg) and histidine (His) in ultraviolet visible (UV–Vis) spectrophotometry. The method is based on the measurement of hypochromic shift of localized surface plasmon resonance (LSPR) absorption band at 395 nm for Arg and 400 nm for His along with new absorption band at 510 nm in the visible region for both the analytes. Further, transmission electron microscope (TEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR) were used to validate the experimental results for selective interaction of target amino acids with AgNPs. The interaction energies between Ag and amino acids were calculated through the optimization of Ag-amino acid complexes using density functional theory (DFT). Experimental results and theoretical calculations provide evidence that the Arg and His bind with guanidinium (N) and imidazole (N) moieties, respectively which causes the aggregation of AgNPs and color change of sample solution. The linear range for determination of Arg and His was calibrated from 0.5–4.5 to 0.5–3.5 µM, respectively with a limit of detection (LOD) of 0.15 µM. The bare-AgNPs is effectively applied for determination of Arg and His in vegetable and fruit samples.