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

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) 3 2+ /ICPn) as the anode luminophore. Under optimized experimental conditions, when potassium persulfate (K 2 S 2 O 8 ) 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 10 4  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.