A comparative performance evaluation of cephalosporin's drugs for fluoride recognition.

In this manuscript, readily available cephalosporin's drugs cefuroxime axetil (L1) cefpdoxime proxetil (L2), and cefditoren pivoxil (L3) possess dihydrothiazine ring as signaling unit, and -NH groups as the binding site were used for the sensing of fluoride (F-) ions. In the presence of F-, the drug selectively portrayed a naked-eye detectable color change from colorless. The binding constant of 1:1 stoichiometric complex of L1, L2, and L3 with F- was found to be 2.36 × 104 M-1, 2.44 × 103 M-1 and 1.02 × 104 M-1 respectively. The lowest detection limit (LOD) of F- was found to be 11 µM (209 ppb) with drug L1 and L2. The binding mechanism of the drug with F- was studied by 1H and 19F nuclear magnetic resonance (NMR) spectral titration, electrospray ionization mass spectra (ESI-MS) analysis, and density functional theory (DFT) studies. The presence of F- was monitored in various spiked water and Colgate toothpaste samples. Overall, cephalosporin's drug demonstrates a promising potential for the detection of F- ions in the semi-aqueous phase.

In vitro studies on the selective cytotoxic effect of luminescent Ru(II)-p-cymene complexes of imidazo-pyridine and imidazo quinoline ligands.

In recent years, Ru(II) complexes have gained high importance in medicinal chemistry due to their significant anti-cancer activities, which are directly related to their DNA binding ability. In this report, the chemistry and cytotoxicity of two new Ru(II) complexes containing imidazole pyridine (Ru-1) and imidazole quinoline (Ru-2) have been studied. The prepared compounds were characterized using infrared (IR), nuclear magnetic resonance (NMR), mass spectrometry (MS), isothermal titration calorimetry (ITC), UV-Vis, and fluorescence spectral techniques. The structural analyses show that the Ru(II) complexes exhibit a 'piano stool' coordination geometry and they are composed of one bound arene, two sigma bonded benzil nitrogen atoms, and labile chlorine linked to Ru(II). The photo-physical properties of these complexes were examined, and they exhibit absorption peaks at 260 nm and 380 nm, which are due to the involvement of intra-ligand charge transitions (ILCT) and metal-to-ligand charge transitions (MLCT), respectively. The binding process of the Ru(II) complexes with DNA and BSA is non-covalent in nature and the binding constants of Ru-1 and Ru-2 complexes with DNA and BSA were found to be 1 × 105 M-1 and 1 × 103 M-1, respectively. In the presence of the Ru(II) complexes, ethidium bromide (EtBr) is competitively displaced from DNA by intercalation of the Ru(II) complexes in DNA and it is well corroborated by viscosity and in silico studies. Both the ligands and Ru(II) complexes were carefully investigated in vitro for cytotoxicity against HeLa, MCF-7, and MDA-MB-231 cells. Surprisingly, both Ru(II) complexes exhibit superior cytotoxicity to cisplatin with a low LD50 value against the examined cancer cells. Besides, an insignificant effect on HEK normal cells (LD50 > 140 µM) was observed.

Rapid detection strategies for the ultra-level chemosensing of uranyl ions.

A simple and reliable colorimetric probe N,N'-bis-(4-diethylamino-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-carbohydrazide (L) has been synthesised by reacting 4-(diethylamino)salicylaldehyde with 1,10-phenanthroline-2,9-dicarbohydrazide. The sensing ability of L was studied by its interactions with various f-block metal ions and other selected metal ions from s- and d-block by colorimetry, UV-visible spectrophotometry, and smartphone integrated red-green-blue (RGB) model in DMSO : H2O (7 : 3, v/v). The pale-yellow colour of L turns to wine-red upon interaction with uranyl ions (UO22+) and yellow-orange in the presence of Th4+, Zr4+, Fe3+, and Lu3+ ions. Other tested metal ions did not show any colour change of L. This color change offered a simple, quick, and consistent method for the selective and sensitive visual detection of trace levels of UO22+ ions without any need for sophisticated instruments. Sensor L exhibits two absorption bands at 358 and 389 nm due to ligand-to-ligand charge transfer (LLCT). Upon interaction of L with UO22+ and Th4+ ions, absorption bands are exhibited at 480 nm and 422 nm, respectively, due to ligand-to-metal charge transfer (LMCT). The UV-vis spectral studies indicated the formation of a 1 : 2 ligand-to-metal complex between L and UO22+ with an estimated association constant of 1.0 × 104 M-2. Using L, the concentration of UO22+ can be detected as low as 73 nM and 150 nM by spectrophotometry and RGB methods, respectively, without any interference from other tested ions with an RSD < 5% (n = 3). The binding mechanism was studied by 1H NMR titration, ESI mass, and FT-IR spectral analysis and was well supported by theoretical results. Overall, sensor L demonstrates promising analytical applicability for the detection of UO22+ ions in a semi-aqueous medium.

A light activated CMP conjugated 8-aminoquinoline turn-on fluorescent optode for selective determination of Th4+ in an aqueous environment.

A new dibutyl(2-oxo-2-(quinolin-8-ylamino)ethyl)phosphinate (L) was designed, synthesised and developed as a light activated optode for Th4+ determination. The sensing performance of L was studied in solution and in the polymeric membrane phase using absorbance and emission techniques. The neutral ion carrier L exhibits weak fluorescence at 400 nm in CH3CN : H2O (9 : 1, v/v). Upon complexation of L with Th4+, the emission intensity at 486 nm was increased 100-fold due to chelation induced enhanced fluorescence. The L-Th4+ binding interaction was studied using both Hill's and Job's plots. They indicate the formation of complex species in a 2 : 1 ratio with an estimated binding constant of 2.66 × 104 M-2. Complex formation between L and Th4+ was studied by NMR (1H, 31P), FTIR and LC-MS analyses. In order to synthesize a probe for the sensing of Th4+ in 100% aqueous medium, the optode was prepared by immobilizing L as a neutral ion carrier in a PVC support using dioctyl phthalate (DOP) as a membrane solvent. The best performance of the optode was observed with a membrane composition of PVC : L : NaTPB : DOP in proportions of 35 : 5 : 3 : 57 (%, w/w) in the pH range of 4.0-8.0. The optode can detect Th4+ concentrations down to 1.1 nM with a fast response time of 15 s and the optical response remains unaltered even after 3 months; the optode sensor can be regenerated using Na2EDTA solution. Finally, the optode was used for the quantification of Th4+ in various water samples, monazite sand, and gas mantle samples.

Highly selective CHEF-type chemosensor for lutetium (III) recognition in semi-aqueous media.

A simple phosphoryl quinolone (L) based sensor has been synthesized for the selective recognition of Lu3+ by spectrofluorimetric method. In methanol-water (1:1, v/v), the ligand L exhibits a weak emission peak at 400 nm upon excitation at 280 nm. Upon interaction with various f-metal and other selected metals from s, p, and d-block elements, the fluorescence of L is selectively enhanced in the presence of Lu3+ due to the chelation enhanced fluorescence (CHEF) effects. The quantum yield (φ) of L (φ = 0.063) is enhanced to φ = 0.118 upon chelation with Lu3+ ion. From the titration experiment, the limit of detection (LOD) of sensor L to recognize Lu3+ is estimated down to 24.2 nM, which is much lower than the WHO guidelines (76 µM) in drinking water. The formation of host-guest complexation between L and Lu3+ in 2:1 binding stoichiometry is studied by Job's method and the binding constant is estimated by band fit analysis (logKf = 5.1). Further, the coordination behaviour between L and Lu3+ is well supported by FT-IR, 1H NMR, 13C NMR, 31P NMR, ESI mass spectral data and the theoretical results.

Accuracy of filter paper method for measuring glycated hemoglobin.

BACKGROUND AND OBJECTIVES: Glycated hemoglobin (HbA1c) provides an accurate and reliable method to assess the glycemic control in patients with Diabetes. Its measurement is limited by the inconvenience of sample collection that requires venipuncture, sample handling and storage factors. The aim of this study was to assess the feasibility of using a dried capillary blood spot on a filter paper to estimate HbA1c, to check its stability at room temperature and to compare these values with the venous sample HbA1c by Turbidimetric Inhibition Immunoassay (TINA, Tina-quant HbA1c II). METHODS: Venous blood samples of seventy eight patients with Type 1 or type 2 diabetes, were collected in EDTA containing vacutainers. Stability of HbA1c was studied in capillary blood samples blotted on to Whatman number 1 filter paper and stored at room temperature, for the first 20 patients enrolled in the study. After establishing the stability over a ten day period, HbA1c values obtained on the capillary blood spots were compared with those obtained from the venous blood samples of the remaining 58 patients. RESULTS: Glycated hemoglobin is found to be stable in dried capillary blood spots on filter paper till the 10th day, stored at room temperature. It however, shows an inherent variability of +/- 15%, which falls within the permissible variability (18%) of the quality control material. Seventy nine percent of the capillary HbA1c values were found to fall within this range. With linear regression, we derived the relationship between filter paper and venous HbA1c values. The regression equation was as follows: Cap.HbA1c = 0.95 (Ven.HbA1c) + 1.4. The filter paper results were highly correlated with the venous sample values (r = 0.889, p < 0.01). CONCLUSION: Measurement of glycated hemoglobin in dried blood spots on filter paper gives reliable and reproducible results. In our study, the mean capillary sample HbA1c value was 12% higher compared to the venous sample HbA1c values. Therefore a higher normal range may have to be used for interpreting the dried blood spot capillary blood HbA1c values.