Bionanoconjugates of horseradish peroxidase and Mn-doped ZnS quantum dots for phosphorescence detection of phenolic compounds

Phenolic compounds have increasingly serious damage to the environment, and it is imperative to develop new detection means for them. In this study, Mn-doped ZnS quantum dot (Mn/ZnS QDs) were synthesized and conjugated with horseradish peroxidase (HRP) via its ligand N-acetyl-L-cysteine (NAC) to form a bionanoconjugates with the phosphorescent response, named Mn/ZnS QDs-HRP. In the presence of a small amount of hydrogen peroxide, phenolic compounds can quench the phosphorescence of Mn/ZnS QDs-HRP, and the quenching type is speculated to be a synergistic effect of dynamic mechanism and internal filtration effect. Taking catechol as an experimental object, the phosphorescence signal of Mn/ZnS QDs-HRP showed a good linear correlation with the concentration of catechol, and the detection limit was 0.068 μM (S/N = 3). The strong anti-interference ability of room temperature phosphorescence endows the probe with excellent sensitivity, and the specific recognition performance of the enzyme makes it have excellent selectivity. Moreover, the probe exhibits good repeatability and stability. When used for actual sample detection, Mn/ZnS QDs-HRP provides stable and reliable quantification of catechol in different water samples with spiked recoveries of 92.3–104.4 %. This study provides a sensitive, convenient, and efficient phosphorescent response sensor for detecting phenolic compounds, which is of positive significance for environmental protection.