Synthesis and Characterization of 1H-Imidazole-4,5-dicarboxylic Acid-Functionalized Silver Nanoparticles: Dual Colorimetric Sensors of Zn²⁺ and Homocysteine

Abstract

A colorimetric assay has been developed for Zn 2+ and homocysteine (Hcy) detection using functionalized silver nanoparticles (AgNPs). AgNPs have been synthesized using silver nitrate, where sodium citrate is used as a stabilizing agent and NaBH 4 as a reducing agent. Then, the nanoparticles (citrate@AgNPs) were functionalized with 1 H -imidazole-4,5-dicarboxylic acid (IDCA). UV–visible and FTIR spectra suggested that IDCA was functionalized on the surface of citrate@AgNPs through the N atom of the imidazole ring. The IDCA-functionalized silver nanoparticles (IDCA@AgNPs) simultaneously detected Zn 2+ and Hcy from aqueous solution and showed different responses to the two analytes (Zn 2+ and Hcy) based on the aggregation-induced color change of IDCA@AgNPs. They showed the color change from yellow to red, which was easily discriminated by visual inspection as well as UV–visible spectroscopy. The surface plasmon resonance absorbance values of Zn 2+ and Hcy are 485 and 512 nm, respectively, when Zn 2+ and Hcy react with IDCA@AgNPs. IDCA@AgNPs showed linearity with Zn 2+ and Hcy concentrations, with the detection limit of 2.38 μM and 0.54 nM, respectively (S/N = 3). The IDCA@AgNPs showed excellent selectivity toward Zn 2+ and Hcy compared to the different metal ions and amino acids, respectively. Optimal detection was achieved toward Zn 2+ and Hcy in the pH range 3–10. In addition, IDCA@AgNPs were used to detect Zn 2+ and Hcy from lake water, showing low interference.

Catalytic Reduction of 4-Nitrophenol and Methylene Blue with Silver Nanoparticles Decorated with Drymoglossum piloselloides Extract

“…i.e., hydroxyl signals at 3000-3750 cm -1 , carbonyl and C=C aromatics at 1500-1750 cm -1 , as well as ether and alkyl groups at 1000-1300 cm -1 , were similar to the FTIR spectrum of the extract. A new absorption signal at 682 cm -1 came from the interaction between D. piloselloides extract with silver as reported in the previous study [37]. The average size of the successfully synthesized silver nanoparticles was 12.630 nm, in agreement with findings in several previous studies showing that nanoparticles with diameters of less than 15 nm generally display remarkable catalytic properties, particularly in the context of reduction catalysis because of their large surface area [38].…”

Silver Nanoparticle-Embedded Carbon Nitride: Antifungal Activity on Candida albicans and Toxicity toward Animal Cells

“…The peaks observed at 809 cm –1 are attributed to the stretching vibrations of the C–N bonds in the triazine units, confirming the presence of nitrogen-containing functional groups in the material. Notably, a new peak observed at approximately ∼671 cm –1 is attributed to the stretching vibrations of Ag–N bonds, confirming the successful incorporation of silver nanoparticles into g-CN . The observed shifts and intensity changes in the bands of Ag@g-CN suggest interactions between g-CN and silver nanoparticles, leading to modifications of the chemical structure and the bonding environment.…”

“…Notably, a new peak observed at approximately ∼671 cm −1 is attributed to the stretching vibrations of Ag−N bonds, confirming the successful incorporation of silver nanoparticles into g-CN. 44 The observed shifts and intensity changes in the bands of Ag@g-CN suggest interactions between g-CN and silver nanoparticles, leading to modifications of the chemical structure and the bonding environment.…”