An Efficient Luminol–H₂O₂ Electrochemiluminescence System with Porous Bimetallic Organic Gels as Signal Booster and Elaborate Heterosequence Aptamer as Recognition Component for Ultrasensitive Biosensing

Herein, an efficient luminol-H₂O₂ electrochemiluminescence (ECL) system with bimetallic organic gels as an ECL signal booster and an innovative heterosequence aptamer recognition as a target conversion strategy is used to construct a sensitive and specific ECL aptasensor for the detection of β₂-microglobulin (B2M), a key biomarker for end-stage renal disease (ESRD). Impressively, the porous Fe@Cu bimetallic organic gels (Fe@Cu MOGs) act as coreaction accelerators and confinement-enhanced reactors of the luminol-H₂O₂ ECL system, amplifying the ECL signal by 21-fold compared to the traditional luminol-H₂O₂ ECL system, which greatly enhanced the sensitivity of the biosensor. Compared to the homosequence aptamer approach with competitive binding of aptamers to a single site, the heterosequence aptamer approach with synergistic binding to multiple sites could greatly improve the specificity of aptasensor, which is validated by experiments and molecular docking simulations. Therefore, the developed aptasensor exhibits a remarkable dynamic range of 10 fg/mL-1 μg/mL with an ultralow detection limit of 0.9 fg/mL, which is superior to previously reported works. Additionally, the aptasensor demonstrated consistent performance with conventional clinical immunoturbidimetric assays for high B2M concentration detection in 14 clinical samples, as well as exhibiting superior sensitivity for trace B2M levels that are undetectable by immunoturbidimetry. This strategy offers a sensitive and accurate platform for biomarker recognition, with promising applications in trace clinical biomarker detection, disease diagnosis, and therapeutic monitoring, as well as in advancing scientific research on early pathological changes and biomarker discovery.