One-step synthesis of fluorescent CDs for highly selective and sensitive detection of TNP and invisible ink applications

Abstract

Glycolurils and substituted glycolurils were utilized for the first time to detect nitro compounds, made possible by a highly sensitive and selective method developed using carbon dots (CDs). This method involves the development of unique and highly selective fluorescent sensors, known as glycoluril-based CDs (GCDs) and diphenyl glycoluril-based CDs (PCDs), which exhibit a “turn-off” response to TNP. Upon the introduction of TNP, the fluorescent sensors exhibited a notable change in color, and rapid fluorescence quenching occurred. The emission behavior of the synthesized GCDs and PCDs displayed two distinct patterns, with the GCDs exhibiting excitation-dependent behavior and PCDs demonstrating excitation-independent characteristics. The sensor probe operated via a FRET mechanism, as confirmed by UV-visible spectroscopy. In addition to good selectivity, the GCDs and PCDs also displayed good sensitivity towards TNP up to 90.53 and 79.423 nM, respectively. Furthermore, we developed a test strip-based sensor that can be used to effectively visualize nitro compounds under UV light. These CDs can be used as fluorescent inks for imaging purposes instead of traditional inks in future applications.