Combining Electrochemiluminescence Detection with Aptamer-Gated Indicator Releasing Mesoporous Nanoparticles Enables ppt Sensitivity for Strip-Based Rapid Tests.

The combination of electrogenerated chemiluminescence (ECL) and aptamer-gated indicator delivering (gAID) magnetic mesoporous silica nanoparticles embedded into glass fibre paper functionalised with poly(ethyleneglycol) and N-(3-triethoxysilylpropyl)diethanolamine allowed the development of a rapid test that detects penicillin directly in diluted milk down to 50±9 ppt in <5 min. Covalent attachment of the aptamer "cap" to the silica scaffold enabled pore closure through non-covalent electrostatic interactions with surface amino groups, while binding of penicillin led to a folding-up of the aptamer thus releasing the ECL reporter Ru(bpy)32+ previously loaded into the material and letting it be detected after lateral flow by a smartphone camera upon electrochemical excitation with a screen printed electrode inserted into a 3D-printed holder. The approach is simple, generic and presents advantages with respect to sensitivity, measurement uncertainty and robustness compared with conventional fluorescence or electrochemical detection, especially for point-of-need analyses of challenging matrices and analytes at ultra-trace levels.

Enhanced electrochemiluminescence by ZnO nanowires for taurine determination.

A novel electrochemiluminescence (ECL) sensor for the sensitive detection of taurine was developed. Taurine contains an aliphatic amine that gives it co-reactant properties. The ECL response of the taurine/[Ru(bpy)3]2+ system was analyzed on two different electrodes surfaces, screen-printed graphene and gold electrodes, before and after modification with ZnO nanowires (ZnO NWs). The ZnO NWs modified electrode yielded an enhanced ECL signal, allowing rapid detection of taurine at 5.5 × 10-6 mol L-1 detection limit. The ECL signal is stable and reproducible. The sensor has been applied to the determination of taurine in a commercial taurine supplement.