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Nanoconfined-structured Ru@COF-LZU1 microenvironment facilitated homogeneous electrochemiluminescence biosensor for ultrasensitive N-nitrosodimethylamine detection

Zhenjie Zheng,Jingxuan Wang,Mengqi Ma,Yunpeng Xu,Da Huang,Jian Wang,Cuiying Lin,Zhenyu Lin,Fang Luo

Sensitive and selective detection of N -nitrosodimethylamine (NDMA), a highly carcinogenic environmental contaminant, is essential for public health and safety. In this study, we have developed a homogeneous electrochemiluminescence (ECL) biosensor for ultrasensitive NDMA detection by integrating Nafion-functionalized covalent organic framework (COF) with aptamer recognition and magnetic separation. The imine-linked COF (COF-LZU1) scaffold not only enables stable encapsulation of Ru(bpy) 3 2 + , but also creates a confined microporous environment that locally concentrates c (TPrA) and enhances the generation and survival of TPrA radicals, thereby amplifying the ECL signal. Nafion further improves Ru loading and ionic conductivity. Biotinylated aptamers were initially immobilized on streptavidin-coated magnetic beads (MBs) and hybridized with complementary DNA-modified Ru@COF-LZU1 to form Ru@COF-LZU1-MBs complex. Upon NDMA binding, a conformational switch releases Ru@COF-LZU1 into the solution. After magnetic separation, the ECL signal of the supernatant is measured in the presence of TPrA. This homogeneous format avoids electrode surface modification, which is commonly required in conventional Ru@COF-LZU1-based ECL sensors, offering improved reproducibility and simplified operation. The biosensor exhibits a wide linear range (100 fg/mL - 100 ng/mL) with a low detection limit of 9.11 fg/mL. This platform offers a sensitive, reproducible, and facile strategy for monitoring NDMA and similar small-molecule contaminants in complex matrices.