Ratiometric electrochemiluminescence biosensor based on Ru(dcbpy)₃²⁺ and TiO₂ quantum dots for the detection of...

Urokinase (UK), an enzymatic protein predominantly isolated from the urine of healthy humans, serves as a crucial biomarker for evaluating human renal function, cardiovascular diseases, and inflammatory states. In this study, a novel sandwich - type ratiometric electrochemiluminescence (ECL) biosensor was constructed to achieve accurate and sensitive detection of UK. This biosensor was constructed with titanium dioxide magnetic beads (P25) as the cathode luminophore and a terbium monophosphate - guanosine infinite coordination polymer network (Tb - GMP ICPn) encapsulating tris(4,4' - dicarboxylic acid - 2,2' - bipyridyl) ruthenium dichloride (Ru(dcbpy)₃²⁺/ICPn) as the anode luminophore. Under optimized experimental conditions, when potassium persulfate (K₂S₂O₈) and tri - n - propylamine (TPA) were separately utilized as co - reactants, a favorable linear correlation was observed between the variations in ECL intensities and the concentration of UK within the range of 10^-2 to 10⁴ ng mL^-1. The limits of detection (LODs) were determined to be 7.2 and 5.8 pg mL^-1, respectively. Moreover, the application of this biosensor for the detection of UK in real - world samples yielded satisfactory results. These findings suggest that the developed ratiometric ECL biosensor holds significant promise in the realm of clinical detection and diagnosis.