Self-assembled emissive probe for efficient sensing of Fe(iii) and cysteine in a physiological medium: application in real water and food samples

Abstract

This investigation involved the synthesis of a novel naphthalimide derivative containing amide functionality (PAD). The study aimed to examine the colorimetric and fluorescence responses of PAD towards different metal ions in an aqueous HEPES buffer solution. The receptor demonstrated a notable preference for Fe(III) when challenged with a significant excess of other ions that compete for binding, resulting in detectable changes in optical and fluorescence properties. The complex between PAD and Fe(III) exhibits notable efficacy in detecting L-cysteine (Cys) with high selectivity. In addition, fluorescence microscopic investigations have indicated that the PAD compound possesses the potential to serve as an imaging probe to detect the uptake of these ions into plant cells, along with the fabrication of portable test strips. Additionally, the demetallation process is involved in the sensing of cysteine. The selective sensing behaviour of PAD towards Fe(III) can be elucidated using the chelation-enhanced fluorescence (CHEF) process, which is further validated by theoretical calculations.