Ru(bpy)₃²⁺‐Loaded Mesoporous Silica Nanoparticles as Electrochemiluminescent Probes of a Lateral Flow Immunosensor for Highly Sensitive and Quantitative Detection of Troponin I

Abstract

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)32+‐loaded mesoporous silica nanoparticles (RMSNs). A large amount of Ru(bpy)32+ 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.

Integrated electrochemical lateral flow immunoassays (eLFIAs): recent advances

“…E-mail: uestc_gjc@163.com attempted to combine ICTSs with electrochemical analysis methods. Since then, the numbers of investigations into eLFIA have increased dramatically; it has been widely applied in numerous fields, including medical diagnosis, 15 food safety, 16 livestock production 13 and drug testing (Fig. 1).…”

Recent Advancements in Enzyme-Based Lateral Flow Immunoassays

“…EC-LFIA systems have been reported in literature based on amperometric, voltammetric and impedimetric detection methods [ 42 , 43 ]. In addition, integration of electrodes on the LFIA strip enabled the use of electrochemiluminescent (ECL) tracers for ECL-LFIA applications, providing high sensitivity, wide detection range and high reproducibility [ 44 ]. However, EC-LFIA systems still suffer from limited applicability, as they present several disadvantages in terms of design of the LFIA system, relatively high costs and complexity of procedures, which involve the addition of specific reagents and require to perform the assay in the solution phase.…”

Integrating high-performing electrochemical transducers in lateral flow assay

“…Further improvements focused on tracer strategies, like metal ligand complexes [17], cellulose nanobeads [18], and the coupling to a smartphone [19]. In the past few years, the research has been focused on further developing labels like Ptnanoparticles (PtNP) [20], the use of Ag staining for amplification [21], combining LFA with SERS [22], implementing nanofibers (NF) [23], using different shapes of colloidal gold [24], using different nanoparticles (NP) like IrO 2 [25] or CuO [26], and integrating electrodes for electrochemiluminescence (ECL) [27]. The texts shown in blue, green, purple, and red represent the development focusing on assay format, signal tracer, detection technique, and recognition element, respectively.…”

“…Figures reprinted from (i) [7], (iv) [19], (v) [23] with permission from Elsevier. Figures reprinted from (ii) [10] and (vi) [27] with permission from John Wiley and Sons. Figure (iii) reprinted from [12] with permission from Royal Society of Chemistry A more recent review focused on detection strategies available for LFAs has also been published by Nguyen et al [32].…”

“…Figures reprinted from (i) [ 7 ], (iv) [ 19 ], (v) [ 23 ] with permission from Elsevier. Figures reprinted from (ii) [ 10 ] and (vi) [ 27 ] with permission from John Wiley and Sons. Figure (iii) reprinted from [ 12 ] with permission from Royal Society of Chemistry …”