Enhanced luminol electrochemiluminescence triggered by an electrode functionalized with dendrimers modified with titanate nanotubes

Screening for electrically conductive defects in thin functional films using electrochemiluminescence

Multifunctional thin films in energy-related devices often must be electrically insulating where a single nanoscale defect can result in complete device-scale failure. Locating and characterizing such defects presents a fundamental problem where high-resolution imaging methods are needed to find defects, but imaging with high spatial resolution limits the field of view and thus the measurement throughput. Here, we present a novel high-throughput method for detecting sub-micron defects in insulating thin films by leveraging the electrochemiluminescence (ECL) of luminol. Through a systematic study of reagent concentrations, buffers, voltage, and excitation time, we identify optimized conditions under which it is possible to detect sub-micron defects at high-throughput. Extrapolating from the signal to background observed for detecting 440 nm wide lines and 620 nm diameter circles, we estimate the minimum detectable features to be lines as narrow as 2.5 nm in width and pinholes as small as 70 nm in radius. We further explore this method by using it to characterize a nominally insulating poly(phenylene oxide) film and find conductive defects that are cross-correlated with high-resolution atomic force microscopy to provide feedback to synthesis. Given this assay's inherent parallelizability and scalability, it is expected to have a major impact on the automated discovery of multifunctional films.

A cloth-based single-working-electrode electrochemiluminescence sensor for simultaneous detection of diabetes complication markers

As one of the most common noninfectious diseases, diabetes and diabetic complications (DDC) have attracted great attention in the field of life and health. However, simultaneous detection of DDC markers usually requires labor- and time-consuming steps. Here, a novel cloth-based single-working-electrode electrochemiluminescence (SWE-ECL) sensor was designed for the simultaneous detection of multiple DDC markers. For this sensor, three independent ECL cells are distributed on the SWE, which is a simplification of the configuration of traditional sensors for simultaneous detection. In this way, the modification processes and ECL reactions occur at the back of the SWE, eliminating the adverse effects caused by human intervention on the electrode. Under optimized conditions, glucose, uric acid and lactate were determined, with corresponding linear dynamic ranges of 80-4000 μM, 45-1200 μM and 60-2000 μM, and detection limits of 54.79 μM, 23.95 μM and 25.82 μM, respectively. In addition, the cloth-based SWE-ECL sensor exhibited good specificity and satisfactory reproducibility, and its actual application potential was verified by measuring complex human serum samples. Overall, this work developed a simple, sensitive, low-cost and rapid method for the simultaneous quantitative determination of multiple markers related to DDC and demonstrated a new route for multiple-marker detection.

TiO2 Nanotubes Decorated with CdSe Quantum Dots: A Bifunctional Electrochemiluminescent Platform for Chiral Discrimination and Chiral Sensing

Chiral analysis is of significant importance for living organisms since chirality is the fundamental phenomenon in nature. In this work, a bifunctional electrochemiluminescent (ECL) platform is constructed for chiral discrimination and chiral sensing. 3-Mercaptopropionic acid-functionalized CdSe quantum dots (CdSe QDs) are combined with aminated TiO₂ nanotubes (NH₂-TiNTs) via amidation. The resultant CdSe QDs/TiNTs display significantly enhanced ECL signals due to the synergistic effect between CdSe QDs and TiNTs, which are then used for the chiral discrimination of the isomers of nine chiral amino acids (AAs) in the presence of d-AA oxidase (DAAO). DAAO can selectively catalyze the oxidation of d-AAs to generate H₂O₂, which acts as the coreaction reagent and triggers the ECL signals of CdSe QDs/TiNTs, and thus, the isomers of the nine chiral AAs can be effectively discriminated. In addition, the as-constructed ECL platform can also be used for the sensitive detection of d-AAs in the presence of DAAO with a wide linear range and a low limit of detection. These findings suggest that the CdSe QDs/TiNTs can work as a bifunctional ECL platform (chiral discrimination and chiral sensing), which might be an advanced ECL platform for biomedical applications.

PAMAM dendrimers: A multifunctional nanomaterial for ECL biosensors

Polyamido amine (PAMAM) dendrimers have been shown to function as electrochemiluminescence (ECL) co-reactant and have the inherent capability of improving immobilization of molecules on surfaces due to their dendritic structure. Here, we investigated the combination of both of these properties as the basis for biosensor development. Dendrimers with 5, 8, 10 and 16 terminal amine groups, respectively, were used. These were covalently coupled to biotin as model recognition site, and tagged with Ru(bpy)₃²⁺ via adsorption. Due to their hydrophilicity, Ru-dendrimers showed significantly improved electrochemical activity in comparison to the standard tripropylamine (TPA) assisted ECL and similar luminescence yields even though 10 fold less dendrimer concentration was required in comparison to TPA. Best signals were obtained for D8 and D10 dendrimers. These Ru-dendrimers were subsequently used for the quantification of streptavidin, as its binding to the biotin-tag caused a proportional decrease in ECL signal with a dynamic range of 5nM to 1μM. These preliminary studies demonstrate that PAMAM dendrimers can function as responsive signal generators in solution-based ECL-bioassays with an assumed even higher impact when being immobilized directly on the electrode-surface.

An ionogel composite including copolymer nanowires for disposable electrochemiluminescent sensor configurations

Aniline derivatives such as luminol and benzidines can be electropolymerized for the preparation of electrochemiluminescent sensors.