Ru(bpy)3 2+ -Loaded Mesoporous Silica Nanoparticles as Electrochemiluminescent Probes of a Lateral Flow Immunosensor for Highly Sensitive and Quantitative Detection of Troponin I.

The lateral flow immunosensor (LFI) is a widely used diagnostic tool for biomarker detection; however, its sensitivity is often insufficient for analyzing targets at low concentrations. Here, an electrochemiluminescent LFI (ECL-LFI) is developed for highly sensitive detection of troponin I (TnI) using Ru(bpy)3 2+ -loaded mesoporous silica nanoparticles (RMSNs). A large amount of Ru(bpy)3 2+ is successfully loaded into the mesoporous silica nanoparticles with excellent loading capacity and shows strong ECL signals in reaction to tripropylamine. Antibody-immobilized RMSNs are applied to detect TnI by fluorescence and ECL analysis after a sandwich immunoassay on the ECL-LFI strip. The ECL-LFI enables the highly sensitive detection of TnI-spiked human serum within 20 min at femtomolar levels (≈0.81 pg mL-1 ) and with a wide dynamic range (0.001-100 ng mL-1 ), significantly outperforming conventional fluorescence detection (>3 orders of magnitude). Furthermore, TnI concentrations in 35 clinical serum samples across a low range (0.01-48.31 ng mL-1 ) are successfully quantified with an excellent linear correlation (R2  = 0.9915) using a clinical immunoassay analyzer. These results demonstrate the efficacy of this system as a high-performance sensing strategy capable of capitalizing on future point-of-care testing markets for biomolecule detection.