A dual-mode electrochemiluminescence/fluorescence biosensor based on CeO₂:Eu³⁺-Au@Au nanomaterials for highly...

Ulinastatin (UTI) is a glycoprotein extracted and purified from human urine. As a protease inhibitor, it mainly functions to inhibit the activity of various proteases such as trypsin and elastase, while also exerting anti-inflammatory effects and protecting tissues and organs. Therefore, the detection of UTI is of great significance in guiding clinical medication, evaluating disease severity, monitoring treatment effects, and judging prognosis. Based on CeO₂:Eu³⁺ nanomaterials and luminol molecules, a dual-mode biosensor integrating electrochemiluminescence (ECL) and fluorescence (FL) was constructed for the sensitive detection of UTI. CeO₂:Eu³⁺ significantly enhanced the ECL intensity of luminol; combined with a sandwich-type immunoreaction, this enabled sensitive and selective ECL detection of UTI. Meanwhile, FL detection of UTI was realized by leveraging the change in the intensity of luminol's characteristic emission peak in FL. Moreover, this dual-mode detection strategy can effectively improve detection accuracy, enabling the detection of UTI with high sensitivity, accuracy, and selectivity. Experimental results showed that the ECL sensor exhibited good linearity for UTI with a limit of detection (LOD) of 8.28 pM in the concentration range of 10^-11-10^-5 M. The FL sensor exhibited good linearity for UTI with a LOD of 0.026 nM in the linear range of 10^-10 - 10^-4 M. When this dual-mode biosensor was applied to the detection of UTI in serum samples, the results of both detection modes were satisfactory.