Oxamic acid and p-aminobenzoic acid functionalized gold nanoparticles as a probe for colorimetric detection of Fe3+ ion

In this work, we have developed a sensitive and selective colorimetric method for detection of Fe3+ ion using oxamic acid (OA) and p-aminobenzoic acid (PABA) functionalized gold nanoparticles (OA-PABA-Au NPs) as a probe. The functionalized Au NPs (OA-PABA-Au NPs) were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopic (FT-IR), and transmission electron microscopic (TEM) techniques, respectively. The Fe3+ ion was induced the aggregation of OA-PABA-Au NPs, yielding a color change from red to blue. The characteristic surface plasmon resonance (SPR) peak of OA-PABA-Au NPs at 523 nm was red-shifted to 685 nm, which confirms the coordination bond between OA-PABA-Au NPs and Fe3+ ions. Under the optimum conditions, a good linear relationship (correlation coefficient R-2 = 0.9905) was obtained between the absorption ratio at A(685)/A(523) and the concentration of Fe3+ over the range of 10-400 mu M. The method showed good selectivity for the assay of Fe3+ ion over other metal ions, and detection limit as low as 5.83 mu M, respectively. The OA-PABA-Au NPs acted as colorimetric sensor for the selective detection of Fe3+ ion in water and biological samples. (C) 2016 Elsevier B.V. All rights reserved.