Sensitive ratiometric sensor for Al(III) detection in water samples using luminescence or eye-vision.

A facile, quick, and sensitive ratiometric luminescence sensor is designed for detection aluminum ions in water samples using luminescence or eye-vision. This approach relies on the emission change of the europium(III) complex with 3-(2-naphthoyl)-1,1,1,-trifluoro acetone (3-NTA) after interaction with various concentration of aluminum ions. The addition of aluminum ions suppressed the Eu(III) emission at 615 nm under 333 nm excitation, while simultaneously enhancing the ligand emission at 480 nm. Optimum detection was obtained in methanol. The quantification of aluminum ions using ratiometric method was determined by plotting the luminescence ratio (F480nm/F615nm) versus aluminum ions concentration. The calibration plot was obtained within the range 0.1-100 µM with LOD = 0.27 µM. Additionally, the concentration of aluminum ions can be estimated semi-quantitatively by visually observing the luminescence colour change of the probe from red to light green and then to dark green after being excited by a UV lamp with 365 nm. As far as we are aware, this is the first luminescent lanthanide complex-based ratiometric probe for the detection of aluminum ions. The probe showed remarkable aluminum ions selectivity relative to that of other metal ions. The suggested sensor was used effectively to identify aluminum ions in water samples with good results.

Fluorescence determination of Fe(iii) in drinking water using a new fluorescence chemosensor.

A new fluorescence chemosensor based on (Z)-2-(1-(3-oxo-3H-benzo[f]chromen-2-yl)ethylidene)hydrazine-1-carbothioamide (CEHC) has been developed for the determination of Fe(iii) in drinking water. The optimum conditions were acetate buffer solution with a pH 5.0. In this approach, the determination of Fe(iii) is based on static quenching of the luminescence of the probe upon increasing concentrations of Fe(iii). The CEHC sensor binds Fe(iii) in a 1 : 1 stoichiometry with a binding constant K a = 1.30 × 104 M-1. CEHC responds to Fe(iii) in a way that is more sensitive, selective, and quick to turn off the fluorescence than to other heavy metal ions. Selectivity was proved against seven other metal ions (Mn(ii), Al(iii), Cu(ii), Ni(ii), Zn(ii), Pb(ii), and Cd(ii)). The calibration curve was constructed based on the Stern-Volmer equation. The linear range was 2.50-150 µM with the correlation coefficient of 0.9994, and the LOD was 0.76 µM. The method was successfully applied to determine Fe(iii) in drinking water samples, and the accuracy of the chemosensor was validated by atomic absorption spectrometry.

Fast and Reliable Synthesis of Melanin Nanoparticles with Fine-Tuned Metal Adsorption Capacities for Studying Heavy Metal Ions Uptake.

PURPOSE: Adsorption and uptake of heavy metals by polymeric nanoparticles is driven by a variety of physicochemical processes. In this work, we examined heavy metal uptake by synthetic melanin nanoparticles and analyzed physicochemical properties that affect the extent of metal uptake by the nanoparticles. METHODS: Eumelanin nanoparticles were synthesized in a one-pot fast process from a 5,6-diacetoxy indole precursor that is hydrolyzed in situ into dihydroxy indole (DHI). The method allows the possibility of changing the level of sodium ions that ends up in the nanoparticles. Two variants of synthetic DHI-melanin (low-sodium and high sodium variants) were evaluated and demonstrated different relative adsorption efficiencies for heavy metal cations. RESULTS AND DISCUSSION: For the low-sodium DHI-melanin and in terms of percentages of metal ion removal, the relative order of extraction from 50 ppm solutions was Zn2+ > Cd2+ > Ni2+ > Co2+ > Cu2+ > Pb2+, with the extraction percentages ranging from 90% down to 76%, for a 30-minute adsorption time before equilibrium. The lower-sodium DHI-melanin consistently removed more Zn2+ than the higher-sodium variant. Electron microscopy (SEM) showed an increase in melanin particle size after metal ions uptake. In addition, X-ray photoelectron spectroscopy (XPS) of DHI-melanin particles with depth profiling after Zn ions uptake supported particle swelling and ion transport within the particles. CONCLUSION: These initial studies showed the potential of this straightforward synthesis to obtain synthetic DHI-melanin nanoparticles similar to those from biological sources with the possibility to fine-tune their metal adsorption capacity. These synthetic nanoparticles can be used either for the removal of a variety of metal ions or to mimic and study mechanisms of metal uptake by melanin deriving from biological sources, with the potential to understand, for instance, differential heavy metal uptake by various melanic pigments.

Echinococcosis of the rib with epidural extension: a rare cause of paraplegia.

Skeletal echinococcosis is a relatively rare entity and that of the rib is exceptional. Less than 50 cases of costal echinococcosis have been reported in the literature so far. Accurate pre-operative diagnosis aids in appropriate management and helps to eradicate the disease. This also prevents the dissemination of parasite and further complications. We report a case of echinococcosis of the rib with epidural extension in a young adult who presented with paraparesis and back pain. His laboratory investigations were within normal limits. Plain radiographs of the dorsal spine, CT scan of thorax and MRI of dorsal spine were performed. The imaging features were suggestive of echinococcosis involving the rib with epidural extension. The cyst was completely resected. Histopathology of the resected specimen confirmed the diagnosis of echinococcosis.