Rapid microwave-assisted green synthesis of guanine-derived carbon dots for highly selective detection of Ag+ in aqueous solution

Abstract

In this work, a simple and green synthetic approach of novel guanine decorated carbon dots (G-CDs) using guanosine 5'-monophosphate and ethylenediamine through a domestic microwave oven was established for the first time. The as-prepared fluorescent G-CDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The obtained fluorescent G-CDs with a uniform morphology had desirable functional groups and excellent optical performances. Furthermore, the fluorescence intensity of G-CDs was remarkably quenched by Ag⁺ than that of other nucleotides-derived CDs. The density functional theory calculations were performed to confirm that the strong interaction of guanine-Ag⁺ was responsible for the remarkable fluorescence response of G-CDs towards Ag⁺. In addition, as a label-free fluorescence probe, the G-CDs displayed a good linear detection for highly selective Ag⁺ sensing over the range of 0-80 μM with the low detection limit of 90 nM. Therefore, the proposed G-CDs had the capacity for Ag⁺ detection in the real samples.

Keywords: Ag(+) detection; Carbon dots; Fluorescent probe; Mechanism analysis; Microwave synthesis.