Carbon dots were synthesized by a simple and green strategy for selective and sensitive Cu(2+) ion detection using both down and upconversion fluorescence. These fluorescent nanosensors show low cytotoxicity and are applied for intracellular sensing and imaging of Cu(2+) in biological systems.

Herein, the reproducibility and a double validation of on-body measurements provided by new wearable potentiometric ion sensors (WPISs) is presented. Sweat collected during sport practice was first analyzed using the developed device, the pH-meter, and ion chromatography (IC) prior to on-body measurements (off-site validation). Subsequently, the accuracy of on-body measurements accomplished by the WPISs was evaluated by comparison with pH-meter readings and IC after collecting sweat (every 10–12.5 min) during sport practice. The developed device contains sensors for pH, Cl–, K+, and Na+ that are embedded in a flexible sampling cell for sweat analysis. The electrode array was fabricated employing MWCNTs (as an ion-to-electron transducer) and stretchable materials that have been exhaustively characterized in terms of analytical performance, presenting Nernstian slopes within the expected physiological range of each ion analyte (Cl–, 10–100 mM; K+, 10–10 mM; and Na+, 10–100 mM and pH, 4.5–7.5), drift suitable for midterm exercise practice (0.3 ± 0.2 mV h–1), fast response time, adequate selectivity for sweat measurements, and excellent reversibility. Besides that, the designed sampling cell avoids any sweat contamination and evaporation issues while supplying a passive sweat flow encompassing specifically the individual’s perspiration. The interpretation of ion concentration profiles may permit the identification of personal dynamic patterns in sweat composition while practicing sport.

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This work presents a detailed study of the photothermal ablation of Kapton® polyimide by a laser diode targeting its electrical conductivity enhancement. Laser-treated samples were structurally characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), as well as Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The results show that the laser-assisted ablation constitutes a simple one-step and environmental friendly method to induce graphene-derived structures on the surface of polyimide films. The laser-modified surface was also electrically characterized through the Transmission Line Method (TLM) aiming at the improvement of the conductivity of the samples by tuning the laser power and the extraction of the contact resistance of the electrodes. Once the laser-ablation process is optimized, the samples increase their conductivity up to six orders of magnitude, being comparable to that of graphene obtained by chemical vapor deposition or by the reduction of graphene-oxide. Additionally, we show that the contact resistance can be decreased down to promising values of ∼2 Ω when using silver-based electrodes.

Four different palladium catalysts were evaluated in order to optimize the conditions in the Suzuki coupling protocol with 1,4-diphenylboronic acid and 9,9-bis(6′-bromohexyl)-2,7-dibromofluorene. The commercially available catalysts [Pd(PPh3)4], (1); [Pd(PPh3)2Cl2], (2); [PdCl2(dppe)], (3) and [PdCl2(dppf)]·CH2Cl2, (4) were chosen. Palladium catalysts 1-4 have been previously used successfully in polymerization. K2CO3 was used as base in the presence of the adequate solvent mixture. Poly[9,9-bis(6′-bromohexylfluoren-2,7-diyl)-alt-co-(benzen-1,4-diyl)], PFPBr 2 , was obtained and selected as model to study the polymerization degree. Calibration curves of fluorene were used to perform a real estimation of the molecular weights of the polymers, and also typical polydispersity values were measured. Polymer conversion was determined using coupled size exclusion chromatography−evaporative light scattering detector (SEC−ELSD). The (Z)-Pd(II) catalyst, (4), which contains the electron acceptor ligand dppf, showed the fastest conversion rate at low reaction times, followed closely by catalyst (2), (E)-Pd(II), which presents a conventional PPh3 ligand. The typical Pd(0) catalyst, (1), with phospane ligands, was slower than others and this process needed almost 12 h to convert the monomers in real polymer. Taken together, all these results provide new insights into the polymerization mechanism using different Pd(II) and Pd(0) catalysts, which seem to behave differently when different ligands are used.

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A novel conjugated polymer microsphere of high value for fluorescent sensing in aqueous media has been synthesized. New conjugated polymers were functionalized in the side chain with imidazole moieties (recognition element) and a terminal double bond (covalently linked to an organic matrix) through a post-functionalization strategy.