Ratiometric fluorescent aptasensor for determination of Golgi Protein 73 based on boron, nitrogen co-doped carbon...

Hepatocellular carcinoma (HCC), characterized by poor early diagnosis, exhibits the second-highest lethality rate among malignancies. This clinical challenge underscores the significance of Golgi protein 73 (GP73) as a promising serum biomarker for HCC detection. Herein, a ratiometric fluorescent aptasensor was constructed employing a dual-signal modulation strategy. The system integrated boron, nitrogen co-doped carbon quantum dots (BNCQDs) as the first fluorescent signal (I₄₄₅) with a functional copper-based metalorganic framework conjugated with GP73-specific aptamer (Cu-MOF-Apt). The latter served dual functions: target recognition and peroxidase-mimetic catalyst for converting o-phenylenediamine (OPD) to 2,3-diaminophenazine (DAP), another fluorescent signal (I₅₆₀). The peroxidase-like activity of Cu-MOF increased with the increase of GP73_Apt attached. In the presence of GP73, target binding induced structural disintegration of Cu-MOF-Apt through GP73-Apt complex formation, thereby suppressing DAP generation. This target-responsive process led to the reduction of the fluorescence intensity of DAP and the increase of the fluorescence intensity of BNCQDs. Under the optimal conditions, the established ratiometric relationship (I₄₄₅/I₅₆₀ = 0.0007X + 0.7021, R² = 0.997) enables quantitative detection of GP73 in the range of 25.00-600.00 ng/mL with the limit of detection (LOD) of 14.06 ng/mL. Clinical validation using serum specimens demonstrated excellent reproducibility (RSD 0.28 %-0.98 %) and recovery rates (99.75 %-107.49 %). The ratiometric fluorescent aptasensor's linear range effectively covers clinically relevant GP73 concentrations in HCC patients, while the robust serum analysis performance confirms its potential for practical diagnostic applications.