Shedding Light on the Diversity of Surfactant Interactions with Luminol Electrochemiluminescence for Bioanalysis

A Green-Emitting Luminol Analogue as the Next-Generation Chemiluminescent Substrate in Biochemical Analysis

Luminol and its derivatives are extensively used as chemiluminogenic substrates in bioimaging and biochemical analysis. Luminol reagents can typically emit blue chemiluminescence (CL), whose wavelength is normally outside the most sensitive detection range of human naked eyes and most CL analyzers with silicon-based charge-coupled device (CCD) detectors. Development of luminol analogues with longer wavelength emission is thus attractive. Herein, four new phthalhydrazide CL probes (GL-1/2/3/4) have been prepared through the derivatization of luminol. The most promising one, 5-(4-hydroxy-1,3-dioxoisoindolin-2-yl)-2,3-dihydrophthalazine-1,4-dione (GL-1), emits bright green CL upon oxidation and shows enhanced CL performance compared to its parent luminol. Bloodstain imaging, horseradish peroxidase (HRP)-based immunoassay, and the analysis of glucose/glucose oxidase reaction have been performed using the GL-1 reagent. These results indicate that GL-1 is a new chemiluminogenic luminol analogue with great potential in real analytical applications and will be an alternative to replace luminol in practical CL analysis.

Genotoxic and inflammatory effects of spruce and brown coal briquettes combustion aerosols on lung cells at the air-liquid interface

Solid fuel usage in residential heating and cooking is one of the largest sources of ambient and indoor air particulate matter, which causes adverse effects on the health of millions of peoples worldwide. Emissions from solid fuel combustion, such as biomass or coal, are detrimental to health, but toxicological responses are largely unknown. In the present study, we compared the toxicological responses regarding cytotoxicity, inflammation and genotoxicity of spruce (SPR) and brown coal briquette (BCB) combustion aerosols on human alveolar epithelial cells (A549) as well as a coculture of A549 and differentiated human monocytic cells (THP-1) into macrophages exposed at the air-liquid interface (ALI). We included both the high emissions from the first hour and moderate emissions from the third hour of the batch combustion experiment in one ALI system, whereas, in the second ALI system, we exposed the cells during the whole 4-hour combustion experiment, including all combustion phases. Physico-chemical properties of the combustion aerosol were analysed both online and offline. Both SPR and BCB combustion aerosols caused mild cytotoxic but notable genotoxic effects in co-cultured A549 cells after one-hour exposure. Inflammatory response analysis revealed BCB combustion aerosols to cause a mild increase in CXCL1 and CXCL8 levels, but in the case of SPR combustion aerosol, a decrease compared to control was observed.

A dual signal-amplified electrochemiluminescence immunosensor based on core-shell CeO2-Au@Pt nanosphere for procalcitonin detection

A dual signal-amplified sandwich electrochemiluminescence (ECL) immunosensor was fabricated for trace detection of procalcitonin (PCT). CeO₂-Au@Pt composed of sea urchin-like Au@Pt nanoparticles coated on CeO₂ hollow nanospheres was immobilized on electrode surface to electrochemically catalyze H₂O₂ to produce a large number of superoxide anion (O₂^•-). The immunosensor was prepared by linking the capture antibody on immobilized CeO₂-Au@Pt with heptapeptide (HWRGWVC), which could maintain the activity of the antibody. The prepared Au star@BSA was used to bind abundant luminol for labeling the secondary antibody (Ab₂). Upon the sandwich-typed immunoreactions, the O₂^•- could react with the introduced luminol on the immunosensor surface to produce strong ECL intensity. With an outstanding linear detection range and a low detection limit of 17 fg/mL, the ECL immunosensor permitted ultrasensitive detection of PCT at a low H₂O₂ concentration and demonstrated its high application potential in the clinical assay.

Co-reactant-free self-enhanced solid-state electrochemiluminescence platform based on polyluminol-gold nanocomposite for signal-on detection of mercury ion

Development of a self-enhanced solid-state ECL platform creates a straightforward experimental design for the fabrication of point-of-care applications. Herein, we develop a promising method for self-enhanced solid-state ECL platform of polyluminol gold nanocomposite on glassy carbon electrode [(PL-Au)_nano/GCE] via simple one-step electrochemical deposition process without involving any additional co-reactants. The presence of gold nanoparticles (AuNPs) augments the electron transfer kinetics of PL (polyluminol) and enhances the solid-state ECL intensity and promotes label-free, excellent sensitivity, and selectivity to detect Hg²⁺ in physiological pH through signal-on mode. Unlike pristine PL/GCE, electrochemically co-deposited AuNPs in the (PL-Au)_nano/GCE composite, enable the co-reactant accelerator by improving the catalytic activity of PL towards oxygen reduction reaction (ORR) yielding in-situ ROS (co-reactant) generation. Further, the ECL intensity of (PL-Au)_nano/GCE composite, gradually increases with each addition of Hg²⁺ ion. This is because of the formation of an amalgamation of Au-Hg on (PL-Au)_nano/GCE composite surface which further accelerates the yield of in-situ ROS and enhances the intensity of ECL. Whereas no ECL signals changes were observed for PL/GCE composite. The proposed self-enhanced solid-state ECL platform is selectively sensing the Hg²⁺ ion in the linear range of 0.3–200 nM with a detection limit of 0.1 nM. The demonstrated (PL-Au)_nano/GCE platform might pave new avenues for further studies in the solid-state ECL platform which could be more useful in on-site monitoring of clinical bioassay and immunosensors.