Innovative Zr-MOF-driven ECL-RET system: highly specific rituximab detection with epitope mimetic peptide CN-14

Therapeutic drug monitoring (TDM) of monoclonal antibodies (mAbs) is critical for realizing personalized dosing and optimizing the benefit-to-risk ratio for patients. In this work, a novel competitive electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was developed for ultra-sensitive rituximab (RTX) detection. A Zr-based metal-organic framework (Zr-MOF) was synthesized via a rapid, facile route using Zr⁴⁺ as the metal node and 9,10-di(p-carboxyphenyl)-anthracene (DPA) as the organic luminescent ligand. The as-prepared Zr-MOF exhibited durable and intense ECL output in 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid buffer with advantages of facile synthesis, remarkable operational stability and outstanding luminescence efficiency. The CD20 epitope mimetic peptide CN-14 was selected as the recognition element for its specific binding affinity to RTX, rendering it ideal for detecting low-concentration analytes in complex biological matrices. By integrating Zr-MOF (as ECL donor) and CN-14 (as affinity ligand) with CoOOH (as ECL acceptor), the constructed ECL-RET immunosensor achieved ultra-sensitive RTX detection with a wide linear range of 1.00 × 10⁻⁴-1.00 × 10² pg mL⁻¹ and an ultra-low limit of detection of 1.44 × 10⁻⁵ pg mL⁻¹. This strategy provides a novel platform for advancing the detection of RTX and other therapeutic mAbs, opening new avenues for clinical TDM applications.