The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing

Construction of an ECL Detection Platform for Sensitive Detection of Carbaryl Based on an Eu3+-Functionalized Metal–Organic Framework Encapsulated with Nanogold

In this work, an Eu3+-MOF-253@Au electrochemiluminescence sensor was successfully constructed for the first time by encapsulating nanogold in the metal–organic frameworks (MOFs) backbone and pore channels, and assembling Eu3+ on the MOF backbone. Firstly, the introduction of nanogold overcomes the weakness of MOFs, which was difficult to achieve, and enhances its catalytic performance, followed by the modification of Eu3+ to confer the electrochemiluminescence performance and the function of target detection on the sensor. Moreover, carbaryl was placed in an alkaline working solution to enhance the intensity of electrochemiluminescence signal, as well as to promote the hydrolysis of carbaryl into 1-naphthol, which caused the burst of Eu3+-MOF-253@Au electrochemiluminescence sensor, thereby achieving the sensitive detection of carbaryl. On this basis, the electrochemiluminescence detection conditions were optimized, the performance was analyzed, and finally it was successfully used for the detection of carbaryl with good linearity in the range of 0.2–200 μg L−1 and a low detection limit (0.14 μg L−1).

One-step sensitive thrombin detection based on a nanofibrous sensing platform

Convenient and time-saving one-step strategies for detecting ultralow concentrations of protein biomarkers play key roles in rapid disease diagnosis. In this study, we report a one-step detection method based on a nanofibrous sensing platform via the combination of proximity-induced DNA strand displacement (PiDSD), catalytic hairpin assembly (CHA) amplification and thioflavin T (ThT) binding. The interface behaviors on the nanofibrous membrane were studied to promote interface reaction kinetics and thermodynamics. Thrombin was used as a model biomarker, and the nanofibrous sensing platform achieved a limit of detection as low as 1.0 pM, a wide linear range of 50 pM to 5 nM, excellent specificity and good long-term stability. Compared with previous one-step thrombin detection methods, our one-step detection method is label-free, convenient and much more sensitive; it has potential applications for protein detection in point-to-care testing (POCT) and early diagnosis.

Combined electrochemiluminescent and electrochemical immunoassay for interleukin 6 based on the use of TiO2 mesocrystal nanoarchitectures

A dual-responsive sandwich-type immunosensor is described for the detection of interleukin 6 (IL-6) by combining electrochemiluminescent (ECL) and electrochemical (EC) detection based on the use of two kinds of TiO₂ mesocrystal nanoarchitectures. A composite was prepared from TiO₂ (anatase) mesocages (AMCs) and a carboxy-terminated ionic liquid (CTIL) and then placed on a glassy carbon electrode (GCE). In the next step, the ECL probe Ru(bpy)₃(II) and antibody against IL-6 (Ab₁) were immobilized on the GCE. Octahedral anatase TiO₂ mesocrystals (OAMs) served as the matrix for immobilizing acid phosphatase (ACP) and secondary antibody (Ab₂) labeled with horseradish peroxidase (HRP) to form a bioconjugate of type Ab₂-HRP/ACP/OAMs. It was self-assembled on the GCE by immunobinding. 1-Naphthol, which is produced in-situ on the surface of the GCE due to the hydrolysis of added 1-naphthyl phosphate by ACP, is oxidized by HRP in the presence of added H₂O₂. This results in an electrochemical signal (typically measured at 0.4 V vs. Ag/AgCl) that increases linearly in the 10 fg·mL^-1 to 90 ng·mL^-1 IL-6 concentration range with a detection limit of 0.32 fg·mL^-1. Secondly, the oxidation product of 1-naphthol quenches the ECL emission of Ru(bpy)₃²⁺. This leads to a decrease in ECL intensity which is linear in the 10 ag·mL^-1 to 90 ng·mL^-1 concentration range, with a detection limit of 3.5 ag·mL^-1. The method exhibits satisfying selectivity and good reproducibility which demonstrates its potential in clinical testing and diagnosis. Graphical abstract A dual-responsive sandwich-type immunosensor was fabricated for the detection of interleukin 6 by combining electrochemiluminescence and electrochemical detection based on the use of two kinds of TiO₂ mesocrystal nanoarchitectures.

Ultrasensitive Visual Detection of HIV DNA Biomarkers via a Multi-amplification Nanoplatform

Methodologies to detect disease biomarkers at ultralow concentrations can potentially improve the standard of living. A facile and label-free multi-amplification strategy is proposed for the ultrasensitive visual detection of HIV DNA biomarkers in real physiological media. This multi-amplification strategy not only exhibits a signficantly low detection limit down to 4.8 pM but also provides a label-free, cost-effective and facile technique for visualizing a few molecules of nucleic acid analyte with the naked eye. Importantly, the biosensor is capable of discriminating single-based mismatch lower than 5.0 nM in human serum samples. Moreover, the visual sensing platform exhibits excellent specificity, acceptable reusability and a long-term stability. All these advantages could be attributed to the nanofibrous sensing platform that 1) has a high surface-area-to-volume provided by electrospun nanofibrous membrane, and 2) combines glucose oxidase (GOx) biocatalysis, DNAzyme-catalyzed colorimetric reaction and catalytic hairpin assembly (CHA) recycling amplification together. This multi-amplification nanoplatform promises label-free and visual single-based mismatch DNA monitoring with high sensitivity and specificity, suggesting wide applications that range from virus detection to genetic disease diagnosis.