Band 91, Heft 10

The solvation structure and dynamics of Cu 2+ in 18.6 % aqueous ammonia have been investigated using an ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulation approach at the Hartree–Fock (HF) level of theory applying the LANL2DZ ECP and Dunning DZP basis sets for Cu 2+ , ammonia and water, respectively. During a simulation time of 20 ps, only NH 3 molecules are observed within the first solvation shell of Cu 2+ , resulting in the formation of an octahedral [Cu(NH 3 ) 6 ] 2+ complex. While no exchange of these ligands with the second solvation shell are observed along the simulation, the monitoring of the associated N-N trans distances highlight the dynamics of the associated Jahn-Teller distortions, showing on average 2 elongated axial (2.19 Å) and 4 equatorial Cu–N bonds (2.39 Å). The observed structural properties are found in excellent agreement with experimental studies. In addition, an NBO analysis was carried out, confirming the strong electrostatic character of the Cu 2+ –NH 3 interaction.

Homopolymer bulk hydrogel of methacrylic acid was synthesized through a new single-step facile rout and used as a template for the fabrication of nickel (Ni) nanoparticles and as adsorbent to remove methylene blue (MB) and Rhodamine-6G (Rh-6G) from water. The Ni nanoparticles containing composite hydrogel was applied as catalyst for the degradation of a nitro compound. The carboxylic groups acted as highly efficient adsorption sites and their high degree was responsible for the removal of huge amounts of MB and Rh-6G from water. The maximum adsorption capacity of poly (methacrylic acid) hydrogel was 685 mg g −1 for MB and 1571 mg g −1 for Rh-6G. The adsorption data of MB was best fitted with Langmuir adsorption isotherm while that of Rh-6G with Temkin adsorption isotherm. Catalytic property of prepared hydrogel integrated with Ni nanoparticles was evaluated by using it as a catalyst for the degradation of 4-nitrophenol (4-NP). The apparent rate constant ( k app ) observed in this study for the reduction of 4-NP was as high as 0.038 min −1 . It was found that this catalyst system can be used repetitively with a slight decrease in catalytic activity.

β-Glucosidase (BG) was immobilized by adsorption on wrinkled silica nanoparticles (WSNs) and on tannic acid-templated mesoporous silica nanoparticles (TA-MSNPs). The effect induced by a different morphology of the pores of the sorbent on the catalytic performance of β-glucosidase was investigated. A complete textural and morphological characterization of the two samples was performed by Brunauer–Emmett–Teller (BET) method, Fourier Transform Infrared (FT-IR) and transmission electron microscopy (TEM). The results demonstrated that the catalytic performance of the immobilized enzyme depends on the pores size of sorbent but a key factor is the pores morphology. In fact, the BG immobilized on WSNs and TA-MSNPs (BG/WSNs and BG/TA-MSNPs) shows in both cases good catalytic performances in cellobiose hydrolysis, but the catalyst with the best performance is BG/WSNs, in which the support exhibits a central-radial pore structure and a hierarchical trimodal micro-mesoporous pore size. This peculiar morphology allows the enzyme to settle in a place where the interactions with the walls are maximized, increasing its conformational rigidity. Furthermore, the enzyme is prevalently collocated in the interior of pore so that the pores are not completely capped.

Microcystins (MCs) are dangerous cyanotoxins for the public health, and microcystin-LR (MC-LR) is one of most toxic, dangerous, and frequently found in water bodies. Typically, the detection of MCs is carried out by means of competitive ELISAs which, however, need special precautions for handling and storage, due to the stability of the antibodies used in this test. Molecularly imprinted nanoparticles (nanoMIPs) represents more robust and cost-effective alternative to antibodies. In this work, we developed a competitive pseudo-ELISA based on nanoMIPs (which are used in place of natural antibodies), for the detection of microcystin-LR (MC-LR). This pseudo-ELISA showed a linear response towards MC-LR, showing high affinity and low cross-reactivity against another analogue toxin (microcystin-YR). The analytical recovery of MC-LR in the analysis of water samples by the proposed pseudo-ELISA was 96 %–130 % and the limit of detection was 2.64 × 10 −4 nM. The obtained results suggest that this competitive pseudo-ELISA could have high potential in the detection of toxins, due to its rapid, sensitive and accurate detection of toxin in water samples.

Bioinspired melanin based hybrid materials hold huge promise for developing multifunctional systems for a considerable set of applications. Yet, control of melanogenic pathway is a big challenge to allow rational design of nanostructured systems with tuned structures and improved properties. This study proves the ability of titanium ions interactions with melanin precursors in directing melanogenic pathway. To this purpose complementary spectroscopic evidences were collected to reveal that in the presence of a TiO 2 -sol, amino-acid complex of Ti(IV) ions and DOPA actually inhibits its cyclization, during oxidative process, thus leading to DOPA-based polyphenols, stable even in oxidative environment, rather than eumelanin. This hugely impacts on the biological properties of the final hybrid systems which, discloses relevant and durable antioxidant behavior but poor antimicrobial activity differently from DHICA-based hybrid nanostructures. Overall this study, discloses the high potential of ceramic templated approach in combination with the selection of melanin precursor in achieving a fine tuning of physico-chemical as well as bioactivity of melanin-TiO 2 nanostructures, opening new scenarios towards the design of cutting-edge biomaterials with tailored biological properties.

The stability of interfaces between polymethyl methacrylate (PMMA) and titanium (Ti) are tested in a Ringer solution that is an aggressive medium usually used for biomaterial evaluation. The devices are PMMA-grafted/Ti elaborated via a “grafting-from” method involving three steps, the alkali activation of Ti sheets, their functionalization with an initiator of polymerization through a phosphonate anchoring group and the growth of PMMA brushes. Electrochemical characterizations demonstrate that the stability of the PMMA-grafted/Ti interface in biological medium is satisfactory and that the grafting of PMMA is even acting as a protective barrier for titanium. Indeed, PMMA-grafted/Ti remains passive in Ringer solution until at least +3 V/SCE (saturated calomel electrode), even under inflammatory conditions, while localized corrosion was measured on as-received titanium in similar conditions. This protecting role is attributed to the grafted interface, since spin-coated PMMA does not decrease the corrosion sensitivity of titanium.

Azadirachta indica (neem) is a tropical and semi-tropical tree native to the whole Indian subcontinent. Neem leaves are rich in flavonoids, which exhibit important pharmacological activities targeting almost all human organs. In order to produce a purified extract of neem leaves enriched of antioxidant and antidiabetic flavonoids, the ethanolic extract of neem leaves has been further undergone to liquid-liquid extractions by using three different organic solvents, i.e. dichloromethane, n-butanol and ethyl acetate. Qualitative and quantitative analyses were performed on the extracts obtained by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Astragalin, quercitrin, isoquercitrin, nicotiflorin and rutin were the only flavonoids found among those screened. By comparing all HPLC chromatograms of purified extracts as obtained with different solvents, it was found that the qualitative-quantitative composition of flavonoids depends upon the extraction solvent used; in particular, dichloromethane allows extraction of 89.5 % quercitrin, 5.3 % isoquercitrin, 5.2 % rutin; n-butanol allows extraction of 6.0 % isoquercitrin, 6.2 % nicotiflorin, 87.8 % rutin; ethyl acetate allows extraction of 4.2 % astragalin, 12.0 % quercitrin, 50.3 % isoquercitrin, 6.7 % nicotiflorin, 26.9 % rutin. Thus, depending on the specific purposes and needs, each of these three extraction solvents has the potential to prepare formulations enriched with the most suitable flavonoids composition.

The role of muscarinic receptors has been largely documented over the past few decades. Recently we demonstrated that the activation of M2 muscarinic receptors arrested cell proliferation and induced apoptosis in glioblastoma and in other tumour types. This paper aims to evaluate the expression of the M2 muscarinic receptor subtypes in different neuroblastoma cell lines and its role in the control of cell proliferation and survival. Neuroblastoma is the most common solid extracranial tumour, appearing during childhood and displaying a differentiated clinical behaviour. Considering the high homology between muscarinic receptor subtypes, we have identified Arecaidine Propargyl Ester (APE) as a selective orthosteric agonist for M2 muscarinic receptors. Using this agonist, we demonstrate how a selective activation of the M2 receptor subtype negatively modulates cell growth without affecting cell survival in different human neuroblastoma cell lines. As similarly demonstrated in other cell types, following the M2 receptor silencing by short-interference RNA, the effects of APE are completely abolished. We conclude by confirming the ability of APE to bind selectively M2 muscarinic receptor subtypes. Moreover, for the first time we demonstrate that M2 receptor activation inhibits cell growth also in human neuroblastoma cells, indicating that M2 receptors may be an interesting therapeutic target in several solid tumours.

Catalysts based on porous polymeric microspheres were prepared from N,N′-Bis(3,3′-allyl-salicylidene)-o-phenylenediamine Pd(II) (PdAS) metallo-monomer, styrene (STY), and divinylbenzene (DVB) as co-monomers. The effects of the STY/PdAS mass ratio of co-monomers were investigated to synthesize the optimal catalyst. All the prepared materials were characterized by scanning electron microscopy (SEM), N 2 adsorption-desorption isotherms, inductively coupled plasma optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), solid-state diffuse-reflectance UV Vis (DRS UV-Vis) spectrometry, and X-ray photoelectron spectroscopy (XPS). Increasing the PdAS content from 1 to 5 wt%, based on the mass feed of monomers, produced well-defined spherical polymer resins with particle diameters of ~200 μm and high surface areas (>500 m 2 /g). XPS spectra shown a unique Pd 2+ signal associated with the PdAS complex immobilized on a porous resin matrix. The catalytic performances of porous polymer microspheres were evaluated for Heck reaction between iodobenzene and methyl acrylate to produce methyl cinnamate, giving up to 100 % selectivity for the trans-isomer. The resin with 5 wt% PdAS showed the best catalytic activity in methyl cinnamate synthesis. Finally, the best catalytic system was evaluated in octinoxate production producing the target product with the same levels of conversion and selectivity for trans-isomer as was detected for methyl cinnamate synthesis.

A pilot study was carried out to evaluate the transfer of As, Cd, Pb, Ni, Cr and Hg from milk to dairy products and to correlate their behavior with that of some components and macro-elements of milk. Due to the low level of these chemical elements in most common commercial products, hard cheese was produced starting from cow’s milk spiked with the analytes of interest. Several intermediate and final products coming from cheese making were sampled and analysed for content of fat, dry matter, proteins, macro and oligo-elements. The relationship between spiked elements and milk components was evaluated through both the study of concentration factors and the statistical analysis (Principal Component Analysis and correlation matrix). Except for As and Hg, a clear correlation between spiked elements and milk components was found so a likely bond with proteins, fat and dry matter was demonstrated. As for Pb, for which a legal limit (Maximum Level, ML) is set in the pertinent European regulations, it was found that the link with proteins could lead to an increase of this element concentration different from the mere concentration factor from milk to cheese. Furthermore, it was proven that the stage of ripening affected the variation of Pb concentration so this aspect should be deeply considered in case of setting a ML in cheese or extrapolating a ML from milk to cheese.

We previously demonstrated that the δ NMR chemical shift of central NMR active atoms (A), in simple halido [AX n ] (A=C, Si, Ge, Sn, Pb, Pt; X n  = combination of n halides, n = 4 or 6) derivatives, could be directly related to X radii overall sum, Σ( r L ). Further correlation have also been observed for tetrahedral [AX 4 ] (A=C, Si; X 4  = combination of four halides) compounds where the X Pauling electronegativities sum, Σ(χLPau),$\Sigma (\chi _L^{{\rm{Pau}}}),$ exceeds a specific value (≈12.4). In this work, we focused on these latter systems considering the H vs. X substitution. The analysis of the literature reported δ( 13 C) and δ( 29 Si) NMR chemical shift for the mono hydrogenated derivatives and in particular for [CHF 3 ] and [SiHF 3 ], characterized by the lowest Σ( r L ) and the highest Σ(χLPau),$\Sigma (\chi _L^{{\rm{Pau}}}),$ suggests a revised value for the H electronegativity ranking with respect to Pauling’s.

The alkali-activation of titanium (Ti) surfaces performed in a heated sodium hydroxide (NaOH) aqueous solution, results in a porous layer rich in hydroxyl (OH) groups, the structure and porosity of which strongly depend on the reaction time and NaOH concentration used. In this study, a polymerization initiator is covalently grafted on the alkali-activated Ti substrates by using a phosphonic acid as coupling agent and the resulting surfaces are used as scaffolds to drive the growth of tethered poly(methyl methacrylate) (PMMA) chains via a surface initiated atom transfer radical polymerisation (SI-ATRP). A close-up investigation of how different treatment times (1 h, 3 h, 6 h, 12 h, and 24 h) and NaOH concentrations (0.1 M, 0.5 M, 1 M, 2 M, and 5 M) affect the final PMMA morphology and thickness are presented.

Twenty seven ( 1–27 ) known natural organic compounds were isolated for first time from two species of Iris , i.e. loczyi and Iris unguicularis. The structures of these compounds were deduced from the spectral data of NMR, IR, and mass spectrogram. These were evaluated against urease and carbonic anhydrase inhibition studies. For carbonic anhydrase-II inhibition studies, these compounds were evaluated by biochemical mechanism based in vitro bio-assay. Some compounds showed significant inhibition against CA-II enzyme. Compartively, compound ( 12 ) showed IC 50 value of 17.60 ± 0.08 μM against urease enzyme, while compound ( 3 ) was found to be most active against carbonic anhydrase-II, having an IC 50 value of 66.27 ± 0.89 μM. Izalpinin ( 3 ), 5,7-dihydroxy-2′,6-dimethoxyisoflavone ( 9 ), 4′,5,7-trihydroxy-6-methoxyflavanone ( 16 ), 4′,5,7-trihydroxy-3′,8-dimethoxyflavanone ( 20 ), 8-methoxyeriodictyol ( 21 ), and mangiferin ( 26 ) were found to be dual inhibitors of both the enyzmes. The most active compounds were docked using Autodock Vina and i-GEMDOCK softwares. The docking and in-vitro results are in agreement which showed secondary interactions with the enzymes. The compounds can serve as therapeutic agents to treat urease and carbonic anhydrase associated disorders.

The benzoin condensation starting from benzaldehyde and the subsequent benzoin amidation to benzamide can be efficiently carried out under very mild conditions in an electrolysis cell. Among the advantages of using electrochemistry to generate our active reagents, the use of the easily dosed and non pollutant electron, instead of stoichiometric amounts of redox reagents or bases, usually renders the electrochemical methodology “greener” than classical organic reactions. Benzoin is obtained in good yield (85 %) carrying out the reaction in the room temperature ionic liquid BMIm-BF 4 . In this electrochemical reaction this liquid salt assumes the double role of solvent-supporting electrolyte system and precatalyst, yielding the corresponding N-heterocyclic carbene. The subsequent benzoin amidation is carried out by electrochemically generated superoxide anion, in the presence of an aliphatic primary or secondary amine. In this case the system superoxide/molecular oxygen acts as base and oxidant, yielding very good yields of benzamides (up to 89 %).