Electrochemical oxidation of o-phenylenediamine and 1,3 dihydrospiro[benzo[d]imidazole-2,1′-cyclohexane]. A comprehensive study and introducing a novel case of CE mechanism

Flexible, Electrochemical Skin-Like Platform for Inflammatory Biomarker Monitoring

Addressing global challenges in wound management has greatly encouraged the emergence of home diagnosis and monitoring devices. This technological shift has accelerated the development of new skin patch sensors for continuous health monitoring. A key requirement is the creation of flexible platforms capable of mimicking human skin features. Here, for the first time, an innovative, highly adaptable electrochemical biosensor with molecularly imprinted polymers (MIPs) is customized for the detection of the inflammatory biomarker interleukin-6 (IL-6). The 3-electrode gold pattern is geometrically standardized onto a 6 µm thick polyimide flexible membrane, an optically transparent, and biocompatible polymeric substrate. Subsequently, a biomimetic sensing layer specifically designed for the detection of IL-6 target is produced on these transducers. The obtained MIP biosensor shows a good linear response within the concentration range 50 pg mL-1-50 ng mL-1, with a low limit of detection (8 pg mL-1). X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations confirm the modifications of the flexible gold transducer. After optimization, the biosensing device shows remarkable potential in terms of sensitivity, selectivity, and reproducibility. Overall, the integration of a low-cost electrochemical sensor on biocompatible flexible polymers opens the way for a new generation of monitoring tools with higher accuracy, less invasiveness, and greater patient comfort.

Direct Electrodeposition of Electrically Conducting Ni3(HITP)2 MOF Nanostructures for Micro-Supercapacitor Integration

Micro-supercapacitors emerge as an important electrical energy storage technology expected to play a critical role in the large-scale deployment of autonomous microdevices for health, sensing, monitoring, and other IoT applications. Electrochemical double-layer capacitive storage requires a combination of high surface area and high electronic conductivity, with these being attained only in porous or nanostructured carbons, and recently found also in conducting metal-organic frameworks (MOFs). However, techniques for conformal deposition at micro- and nanoscale of these materials are complex, costly, and hard to upscale. Herein, the study reports direct, one step non-sacrificial anodic electrochemical deposition of Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 - Ni3(HITP)2, a porous and electrically conducting MOF. Employing this strategy enables the growth of Ni3(HITP)2 films on a variety of 2D substrates as well as on 3D nanostructured substrates to form Ni3(HITP)2 nanotubes and Pt@ Ni3(HITP)2 core-shell nanowires. Based on the optimal electrodeposition protocols, Ni3(HITP)2 films interdigitated micro-supercapacitors are fabricated and tested as a proof of concept.

Dual-emissive carbonized polymer dots for the ratiometric fluorescence imaging of singlet oxygen in living cells

Singlet oxygen (¹O₂) is a type of reactive oxygen species (ROS), playing a vital role in the physiological and pathophysiological processes. Specific probes for monitoring intracellular ¹O₂ still remain challenging. In this study, we develop a ratiometric fluorescent probe for the real-time intracellular detection of ¹O₂ using o-phenylenediamine-derived carbonized polymer dots (o-PD CPDs). The o-PD CPDs possessing dual-excitation-emission properties (blue and yellow fluorescence) were successfully synthesized in a two-phase system (water/acetonitrile) using an ionic liquid tetrabutylammonium hexafluorophosphate as a supporting electrolyte through the electrolysis of o-PD. The o-PD CPDs can act as a photosensitizer to produce ¹O₂ upon white LED irradiation, in turn, the generated ¹O₂ selectively quenches the yellow emission of the o-PD CPDs. This quenching behavior is ascribed to the specific cycloaddition reaction between ¹O₂ and alkene groups in the polymer scaffolds on o-PD CPDs. The interior carbon core can be a reliable internal standard since its blue fluorescence intensity remains unchanged in the presence of ¹O₂. The ratiometric response of o-PD CPDs is selective toward ¹O₂ against other ROS species. The developed o-PD CPDs have been successfully applied to monitor the ¹O₂ level in the intracellular environment. Furthermore, in the inflammatory neutrophil cell model, o-PD CPDs can also detect the ¹O₂ and other ROS species such as hypochlorous acid after phorbol 12-myristate 13-acetate (PMA)-induced inflammation. Through the dual-channel fluorescence imaging, the ratiometric response of o-PD CPDs shows great potential for detecting endogenous and stimulating ¹O₂in vivo.

Mechanochemical Synthesis of Polyanilines and Their Nanocomposites: A Critical Review

The mechanochemical synthesis of polyanilines (PANIs), made by oxidative polymerization of anilines, is reviewed. First, previous knowledge of the polymerization reaction in solution is discussed to understand the effect of different parameters: oxidant/monomer ratio, added acid, oxidant, temperature and water content on the properties of the conducting polymers (molecular weight, degradation, doping/oxidation level, conductivity, and nanostructure). The work on mechanochemical polymerization (MCP) of anilines is analyzed in view of previous data in solution, and published data are critically reconsidered to clarify the interpretation of experimental results. A key factor is the production of acids during polymerization, which is often overlooked. The production of gaseous HCl during MCP of aniline hydrochloride is experimentally observed. Since some experiments involves the addition of small amounts of water, the kinetics and heat balance of the reaction with concentrated solutions were simulated. A simple experiment shows fast (<2 min) heating of the reaction mixture to the boiling point of water and temperature increments are observed during MCP in a mortar. The form and sizes of PANI nanostructures made by MCP or solution are compared. The extensive work on the production of nanocomposites by MCP of anilines together with different nanomaterials (porous clays, graphene, carbon nanotubes, metal, and oxide nanoparticles) is also described.

A green protocol for the electrochemical synthesis of a fluorescent dye with antibacterial activity from imipramine oxidation

Electrochemical oxidation of imipramine (IMP) has been studied in aqueous solutions by cyclic voltammetry and controlled-potential coulometry techniques. Our voltammetric results show a complex behavior for oxidation of IMP at different pH values. In this study, we focused our attention on the electrochemical oxidation of IMP at a pH of about 5. Under these conditions, our results show that the oxidation of IMP leads to the formation of a unique dimer of IMP (DIMP). The structure of synthesized dimer is fully characterized by UV-visible, FTIR, ¹H NMR, ¹³C NMR and mass spectrometry techniques. It seems that the first step in the oxidation of IMP is the cleavage of the alkyl group (formation of IMPH). After this, a domino oxidation-hydroxylation-dimerization-oxidation reaction, converts IMPH to (E)-10,10',11,11'-tetrahydro-[2,2'-bidibenzo[b,f]azepinylidene]-1,1'(5H,5'H)-dione (DIMP). The synthesis of DIMP is performed in an aqueous solution under mild conditions, without the need for any catalyst or oxidant. Based on our electrochemical findings as well as the identification of the final product, a possible reaction mechanism for IMP oxidation has been proposed. Conjugated double bonds in the DIMP structure cause the compound to become colored with sufficient fluorescence activity (excitation wave-length 535 nm and emission wave-length 625 nm). Moreover, DIMP has been evaluated for in vitro antibacterial. The antibacterial tests indicated that DIMP showed good antibacterial performance against all examined gram-positive and gram-negative bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Shigella sonnei).