Water-stable Cu-based coordination polymer for ratiometric fluorescence detection of riboflavin

Riboflavin was first isolated from milk and widely used in food, biological and pharmaceutical fields. Accurate detection of riboflavin content is of great significance for the treatment of related diseases and the supervision of food/drug quality. In this paper, a 1D chain copper-based coordination polymer with excellent water stability was synthesized by hydrothermal method using rigid ligand 1,10-phenanthroline and flexible ligand 1,4-phenylenedioxydiacetic acid, named Cu-phen-PEDA. Based on the Förster resonance energy transfer (FRET) and dynamic quenching detection mechanism, the emission spectrum of Cu-phen-PEDA overlaps with the absorption spectrum of riboflavin. As an energy donor in this case, Cu-phen-PEDA significantly increases the fluorescence intensity of riboflavin (energy acceptor), while simultaneously decreasing its own fluorescence intensity, which is an effective proportional-building strategy. In the lower concentration range, riboflavin can be specifically recognized by ratiometric fluorescence with a good linear relationship, and the detection limit is as low as 23 nM. The potential aspects of its specificity, stability, reusability and practical application were explored.