WSe2 nanosheets with peroxidase-mimetic activity and carbon dots based ratiometric fluorescent strategy for D-galactose sensing.

D-Galactose (D-Gal), an essential monosaccharide, plays multiple physiological roles in living organisms. Abnormal fluctuations in its concentration are closely associated with various genetic metabolic disorders, such as galactosemia and galactose deficiency. Therefore, the development of an efficient, sensitive, and accurate method for D-Gal detection is critical for disease diagnosis and treatment. In this study, a ratiometric fluorescence-based sensing platform was constructed for the quantitative detection of D-Gal. Galactose oxidase can catalyze the oxidation of D-Gal, resulting in the generation of hydrogen peroxide (H₂O₂). When combined with WSe₂ nanosheets prepared via liquid-phase exfoliation and functioning as nanozymes, in the presence of H₂O₂, the substrate o-phenylenediamine (OPD) undergoes oxidation to generate 2,3-diaminophenazine (DAP), which exhibits a fluorescence peak at 570 nm. Simultaneously, DAP quenches the fluorescence of carbon dots (CDs) at 430 nm via an inner filter effect, thereby enabling ratiometric detection with enhanced accuracy and sensitivity. The method exhibits a Limit of detection of 0.004 mM, Linear ranges spanning from 0.01 to 1 mM and from 1 to 300 mM, with recoveries ranging between 91.0 and 100.4%. Furthermore, the proposed method was effectively utilized for the detection of D-Gal in human serum specimens, demonstrating excellent selectivity and reliability. This research presents a novel method for D-Gal detection based on WSe₂ nanosheets and CDs, offering potential applications in the biomedical and biosensing fields.