Highly sensitive electrochemical immunosensor for alpha-fetoprotein detection based on trimetallic metal-organic framework nanozymes with peroxidase-like activity.

Quantitative analysis of alpha-fetoprotein (AFP) in biological samples is essential for early diagnosis, accurate monitoring, and assessment of therapeutic efficacy. We developed a sandwich-type electrochemical biosensor based on trimetallic nanozyme for AFP sensitive detection. The UiO-66-NH2@Au/AgNPs nanozyme was assembled via 11-mercaptoundecanoic acid (MUA) modification, and displayed exceptional peroxidase-like activity, due to its dense catalytic sites and synergistic multimetal effects. Besides, steady-state kinetic experiments were further performed to elucidate the structure-activity relationships of the trimetallic nanozyme. To enhance detection sensitivity, a MoS2/Ni3(HITP)2 composite was employed as the substrate, leveraging its superior electrical conductivity to significantly amplify the biosensor signal. As a result, by determinating the nanozyme-catalyzed current response toward H2O2, the electrochemical platform achieved a wide linear range of 0.075-1000 ng·mL- 1, with a limit of detection (LOD) of 0.05 ng·mL- 1. The practical utility of this method was validated via spiked recovery tests in real samples, yielding an acceptable recovery of 90.98%-109.20%, and relative standard deviations (RSD) below 14.68%. Overall, this sandwich-type strategy combines the rapid response of electrochemical detection with the high specificity of antigen-antibody recognition. Although further optimization and validation are warranted for broader practical applications, the proposed platform demonstrates considerable potential for point-of-care testing and clinical cancer diagnosis.