Heteropentanuclear Oxalato‐Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis,Crystal Structures,Aqueous Stability and Antiproliferative Activity

A series of heteropentanuclear oxalate‐bridged Ru(NO)‐Ln (4d–4f) metal complexes of the general formula (nBu₄N)₅[Ln{RuCl₃(μ‐ox)(NO)}₄], where Ln=Y ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ) and ox=oxalate anion, were obtained by treatment of (nBu₄N)₂[RuCl₃(ox)(NO)] ( 1 ) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1 , 2 , and 5 were in addition analyzed by X‐ray crystallography, 1 by Ru K‐edge XAS and 1 and 2 by ¹³C NMR spectroscopy. X‐ray diffraction showed that in 2 and 5 four complex anions [RuCl₃(ox)(NO)]^2? are coordinated to Y^III and Dy^III, respectively, with formation of [Ln{RuCl₃(μ‐ox)(NO)}₄]^5? (Ln=Y, Dy). While Y^III is eight‐coordinate in 2 , Dy^III is nine‐coordinate in 5 , with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu₄N⁺ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium‐lanthanide complexes 2 – 5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC‐5) and compared with those obtained for the previously reported Os(NO)‐Ln (5d–4f) analogues (nBu₄N)₅[Ln{OsCl₃(ox)(NO)}₄] (Ln=Y ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 )). Complexes 2 – 5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6 – 9 in terms of IC₅₀ values. The highest antiproliferative activity with IC₅₀ values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP‐MS data, indicating five‐ to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells.     

Combinatorial electrochemistry using metal nanoparticles: from proof-of-concept to practical realisation for bromide detection

Principles and practical application of combinatorial electrochemistry in search for new electroactive materials in electroanalysis have been explored. Nanoparticles of three different metals: silver, gold and palladium have been independently synthesized on the glassy carbon spherical powder surface by electroless deposition process and characterized using both spectroscopic and electrochemical techniques. These three materials were then combined together onto basal plane pyrolytic graphite electrode surface and the application of the combinatorial approach to find the electrode material for bromide detection as model target analyte was demonstrated. The component electroactive for bromide detection was next identified and it was found that silver nanoparticles were the active ones. A composite electrode based on silver nanoparticle modified glassy carbon powder and epoxy resin was then fabricated and it was found to allow accurate determination of bromide. The electroactivity for the bromide determination of the composite electrode was compared with that of a bulk silver electrode and it was shown that the composite electrode is very efficient with a comparable electroactivity with only a portion of precious metals being used for its construction.     

Comparison of Hydroxyapatite/Poly(lactide-co-glycolide) and Hydroxyapatite/Polyethyleneimine Composite Scaffolds in Bone Regeneration of Swine Mandibular Critical Size Defects: In Vivo Study

Reconstruction of jaw bone defects present a significant problem because of specific aesthetic and functional requirements. Although widely used, the transplantation of standard autograft and allograft materials is still associated with significant constraints. Composite scaffolds, combining advantages of biodegradable polymers with bioceramics, have potential to overcome limitations of standard grafts. Polyethyleneimine could be an interesting novel biocompatible polymer for scaffold construction due to its biocompatibility and chemical structure. To date, there have been no in vivo studies assessing biological properties of hydroxyapatite bioceramics scaffold modified with polyethyleneimine. The aim of this study was to evaluate in vivo effects of composite scaffolds of hydroxyapatite ceramics and poly(lactide-co-glycolide) and novel polyethyleneimine on bone repair in swine’s mandibular defects, and to compare them to conventional bone allograft (BioOss). Scaffolds were prepared using the method of polymer foam template in three steps. Pigs, 3 months old, were used and defects were made in the canine, premolar, and molar area of their mandibles. Four months following the surgical procedure, the bone was analyzed using radiological, histological, and gene expression techniques. Hydroxyapatite ceramics/polyethyleneimine composite scaffold demonstrated improved biological behavior compared to conventional allograft in treatment of swine’s mandibular defects, in terms of bone density and bone tissue histological characteristics.     

Electrocatalytic Behavior of an Amide Functionalized Mn(II) Coordination Polymer on ORR,OER and HER

The new 3D coordination polymer (CP) [Mn(L)(HCOO)]_n (Mn-CP) [L = 4-(pyridin-4-ylcarbamoyl)benzoate] was synthesised via a hydrothermal reaction using the pyridyl amide functionalized benzoic acid HL. It was characterized by elemental, FT-IR spectroscopy, single-crystal and powder X-ray diffraction (PXRD) analyses. Its structural features were disclosed by single-crystal X-ray diffraction analysis, which revealed a 3D structure with the monoclinic space group P21/c. Its performance as an electrocatalyst for oxygen reduction (ORR), oxygen evolution (OER), and hydrogen evolution (HER) reactions was tested in both acidic (0.5 M H₂SO₄) and alkaline (0.1 M KOH) media. A distinct reduction peak was observed at 0.53 V vs. RHE in 0.1 M KOH, which corresponds to the oxygen reduction, thus clearly demonstrating the material’s activity for the ORR. Tafel analysis revealed a Tafel slope of 101 mV dec⁻¹ with mixed kinetics of 2e⁻ and 4e⁻ pathways indicated by the Koutecky–Levich analysis. Conversely, the ORR peak was not present in 0.5 M H₂SO₄ indicating no activity of Mn-CP for this reaction in acidic media. In addition, Mn-CP demonstrated a noteworthy activity toward OER and HER in acidic media, in contrast to what was observed in 0.1 M KOH.     

Phytochemistry and Antihyperglycemic Potential of Cistus salviifolius L., Cistaceae

Cistus salviifolius has been previously reported as a traditional remedy for hyperglycemia. However, the plant has been scarcely investigated from scientific point of view. Thus, the aim was to examine the chemical composition and to evaluate its antioxidant and antihyperglycemic potential in vitro. Aqueous and ethanolic extracts were evaluated for total phenolic, tannin, and flavonoid content using spectrophotometric methods. Detailed chemical characterization was performed by high-performance liquid chromatography (HPLC-DAD). The volatile organic compounds (VOCs) profile was assessed by gas chromatography technique. The potential in diabetes treatment was evaluated through tests of free radicals neutralization, inhibition of lipid peroxidation process, and test of ferric ion reduction; activity in tests of inhibition of α-amylase, α-glucosidase and dipeptidyl peptidase-4 was also evaluated. High content of phenolics (majority being tannins) was detected; detailed HPLC analysis revealed high content of gallic acid, followed by rutin, chlorogenic and caffeic acids. The VOCs analysis determined sesquiterpene hydrocarbons and oxygenated sesquiterpenes as the main groups of compounds. The assays classified extracts as potent neutralizers of 2,2-diphenyl-1-picrylhydrazil and nitroso radicals formation and potent inhibitors of α-amylase and α-glucosidase. In conclusion, Cistus salviifolius represents a rich source of phenolics and essential oil with sesquiterpenes. The established results suggested its promising antioxidant and antihyperglycemic activities.     

pH-Responsive Hydrogel Beads Based on Alginate, κ-Carrageenan and Poloxamer for Enhanced Curcumin,Natural Bioactive Compound,Encapsulation and Controlled Release Efficiency

Polyphenolic compounds are used for treating various diseases due to their antioxidant and anticancer properties. However, utilization of hydrophobic compounds is limited due to their low bioavailability. In order to achieve a greater application of hydrophobic bioactive compounds, hydrogel beads based on biopolymers can be used as carriers for their enhanced incorporation and controlled delivery. In this study, beads based on the biopolymers-κ-carrageenan, sodium alginate and poloxamer 407 were prepared for encapsulation of curcumin. The prepared beads were characterized using IR, SEM, TGA and DSC. The curcumin encapsulation efficiency in the developed beads was 95.74 ± 2.24%. The release kinetics of the curcumin was monitored in systems that simulate the oral delivery (pH 1.2 and 7.4) of curcumin. The drug release profiles of the prepared beads with curcumin indicated that the curcumin release was significantly increased compared with the dissolution of curcumin itself. The cumulative release of curcumin from the beads was achieved within 24 h, with a final release rate of 12.07% (gastric fluid) as well as 81.93% (intestinal fluid). Both the in vitro and in vivo studies showed that new hydrogel beads based on carbohydrates and poloxamer improved curcumin’s bioavailability, and they can be used as powerful carriers for the oral delivery of different hydrophobic nutraceuticals.     

Effects of Precursors and Plasma Parameters on Fullerene Synthesis in RF Thermal Plasma Reactor

Synthesis of fullerenes from graphite powders of different grade was studied in a radiofrequency (RF) plasma reactor. Dependence of fullerene yield on the properties and feed rate of precursors and on the helium content of plasma gas was studied in details. The fullerene yield was influenced by the mean size and the thermal conductivity of graphite particles on the one hand, and the helium content of the gas phase on the other. Soot containing fullerene mixture of 5.9% was produced in best conditions found in this work. The main component of the fullerene mixture was C₆₀. In addition, it contained about 30% of C₇₀ (corresponding to a C₆₀/C₇₀ mass ratio of 2.64). Higher fullerenes such as C₈₄ were also detected by mass spectroscopy (MS) and high performance liquid chromatography (HPLC).     

Application of potentiometric stripping analysis with constant inverse current for determining soluble lead in human teeth

A method for the determination of soluble lead in human teeth by potentiometric stripping analysis with constant inverse current in the analytic step (PSA-i_R), is described. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. This paper examined effect of various factors on the PSA-i_R results including the electrolysis potential, the solution stirring rate, and the constant inverse current. Quantitative analysis was carried out by both standard addition and calibration curve methods; a good linearity was obtained in the concentration range from 5 to 25 μg/dm³. A detection limit of 0.64 μg/dm³ was obtained, with a 5.21% coefficient of variation. Results obtained for teeth were not significantly different from these obtained by flameless atomic absorption spectrophotometry (FAAS).     

A note on the article “Fuzzy alpha-sets and alpha-continuous maps”

In this note we show that some results which appeared in the article by M.K. Singal and N. Rajvanshi [Fuzzy Sets and Systems 48 (1992) 383–390] are incorrect.     

Determination of carbamazepine and its impurities iminostilbene and iminodibenzyl in solid dosage form by column high-performance liquid chromatography

An accurate and precise RP-HPLC method was developed and validated for the determination of carbamazepine and its impurities iminostilbene and iminodibenzyl in a tablet formulation with fluphenazine as an internal standard. Buffer-methanol (50 + 50, v/v) was used as the mobile phase. During validation, specificity, linearity, precision, accuracy, LOD, LOQ, and robustness of the method were tested. The method was proven to be specific against placebo interference. Linearity was evaluated over the concentration range of 100-500, 0.05-0.25, and 0.1-0.5 microg/mL, and the r values were 0.9994, 0.9997, and 0.9979 for carbamazepine, iminostilbene, and iminodibenzyl, respectively. Intraday precision of the method was good, and RSD was below 2% for all analytes. The accuracy of the method ranged from 100.69 to 102.10, 99.76 to 102.66, and 99.26 to 100.08% for carbamazepine, iminostilbene, and iminodibenzyl, respectively. LOD was 0.0125, 0.025, and 0.05 microg/mL and LOQ was 0.05, 0.05, and 0.1 microg/mL for carbamazepine, iminostilbene, and iminodibenzyl, respectiviely. Robustness of the method was proven by using a chemometric approach. The method was successfully applied to the analysis of commercially available carbamazepine tablets and showed good repeatability, with RSD below 2%.