Nanoparticle Delivery Systems in the Treatment of Diabetes Complications.

Diabetes mellitus, an incurable metabolic disease, is characterized by changes in the homeostasis of blood sugar levels, being the subcutaneous injection of insulin the first line treatment. This administration route is however associated with limited patient's compliance, due to the risk of pain, discomfort and local infection. Nanoparticles have been proposed as insulin carriers to make possible the administration of the peptide via friendlier pathways without the need of injection, i.

Cationic Surfactants: Self-Assembly, Structure-Activity Correlation and Their Biological Applications.

The development of biotechnological protocols based on cationic surfactants is a modern trend focusing on the fabrication of antimicrobial and bioimaging agents, supramolecular catalysts, stabilizers of nanoparticles, and especially drug and gene nanocarriers. The main emphasis given to the design of novel ecologically friendly and biocompatible cationic surfactants makes it possible to avoid the drawbacks of nanoformulations preventing their entry to clinical trials. To solve the problem of toxicity various ways are proposed, including the use of mixed composition with nontoxic nonionic surfactants and/or hydrotropic agents, design of amphiphilic compounds bearing natural or cleavable fragments.

Self-assembling systems based on quaternized derivatives of 1,4-diazabicyclo[2.2.2]octane in nutrient broth as antimicrobial agents and carriers for hydrophobic drugs.

Aggregation properties of mono (mono-CS) and dicationic (di-CS) surfactants, namely quaternised derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO), have been evaluated in water and in nutrient broths of different pH, i.

A gold cyano complex in nitromethane: MD simulation and X-ray diffraction.

The solvation structure around the dicyanoaurate(I) anion (Au(CN)) in a dilute nitromethane (CHNO) solution is presented from X-ray diffraction measurements and molecular dynamics simulation (NVT ensemble, 460 nitromethane molecules at room temperature). The simulations are based on a new solute-solvent force-field fitted to a training set of quantum-chemically derived interaction energies. Radial distribution functions from experiment and simulation are in good agreement.

Theoretical analysis of spin crossover in iron(II) [2×2] molecular grids.

We use quantum-chemical density functional theory calculations to elucidate the origin of spin-crossover pathways in two iron(II) [2×2] molecular grids with carbohydrazide-based bridging ligands. The complexes are characterized energetically and structurally in five available spin states. Special attention is paid to analysis of the structural distortion induced on each iron center by spin transition on any of its neighbors.

Spin crossover in tetranuclear cyanide-bridged iron(II) square complexes: a theoretical study.

Spin crossover in a series of six cyanide-bridged iron(II) tetranuclear square complexes was analyzed using density functional theory (DFT) methods. As the spin crossover between the low-spin (LS) and high-spin (HS) states can occur only for two of four iron ions, we characterized energetically and structurally the [LS-LS], [HS-LS], and [HS-HS] spin-state isomers. For all studied complexes, the energy of the mixed [HS-LS] spin state does not deviate essentially from the halfway point between the energies of homogeneous spin states, thereby satisfying the conditions for an one-step transition between the [LS-LS] and [HS-HS].

Experimental and theoretical Mössbauer study of an extended family of [Fe8(μ4-O)4(μ-4-R-px)12X4] clusters.

Six [Fe(8)(μ(4)-O)(4)(μ-4-R-pyrazolato)(12)X(4)] complexes containing an identical Fe(8)(μ(4)-O)(4) core have been structurally characterized and studied by Mössbauer spectroscopy. In each case, an inner μ(4)-O bridged Fe(III) cubane core is surrounded by four trigonal bipyramidal iron centers, the two distinct sites occurring in a 1:1 ratio. The Mössbauer spectrum of each of the clusters consists of two quadrupole doublets, which, with one exception (X = NCS, R = H), overlap to give three absorption lines.

A spectroscopic and computational study of Al(III) complexes in sodium cryolite melts: ionic composition in a wide range of cryolite ratios.

The structure of sodium cryolite melts was studied using Raman spectroscopy and quantum chemical calculations performed at the density functional theory level. The existence of bridged forms in the melts was argued first from the analysis of experimental Raman spectra. In the quantum chemical modelling emphasis was put on the construction of potential energy surfaces describing the formation/dissociation of certain complex species.

Redox potential of the Rieske iron-sulfur protein quantum-chemical and electrostatic study.

Quantum-chemical study of structures, energies, and effective partial charge distribution for several models of the Rieske protein redox center is performed in terms of the B3LYP density functional method in combination with the broken symmetry approach using three different atomic basis sets. The structure of the redox complex optimized in vacuum differs markedly from that inside the protein. This means that the protein matrix imposes some stress on the active site resulting in distortion of its structure.

Electronic structure and magnetic properties of a trigonal prismatic Cu(II)6 cluster.

A combination of detailed magnetisation studies and electronic-structure analysis using broken-symmetry DFT is used to explore the electronic structure of a trigonal prismatic Cu(II)(6) cluster. The presence of six paramagnetic metal centres with S = 1/2 gives rise to a maximum multiplicity of S = 3 and a total of 31 broken-symmetry states with M(S) < 3. Computed differences in energy between the high-spin and broken-symmetry states are expressed in terms of the 15 distinct Heisenberg exchange coupling parameters, J(ij), and the equations are solved by a least-squares fitting procedure.

Interplay between solvent effects of different nature in interfacial bond breaking electron transfer.

Solvent dynamics effects on electroreduction of peroxodisulphate anion on mercury electrode (a typical bond breaking electron transfer reaction) are explored in the framework of the Sumi-Marcus model. The reaction three-dimensional free energy surface is constructed using the Anderson model Hamiltonian. A new interpretation of short- and long-time survival times is presented as well.

Reversed-phase liquid chromatographic determination of isoniazide in human urine as a test of the genetically predetermined type of biotransformation by acetylation.

A new method of determination of genetically predetermined type of biotransformation by acetylation rate using reversed-phase liquid chromatography (RP-HPLC) was described. The method is based on determination of isonicotinic hydrazide (INH) which is excreted with the patient's urine during 24 h period after oral administration of 0.4 g of the drug.

Medium and interfacial effects in the multistep reduction of binuclear complexes with robson-type ligand.

We present a combined experimental and computational approach to the modeling and prediction of reactivity in multistep processes of heterogeneous electron transfer. The approach is illustrated by the study of a Robson-type binuclear complex (-Cu(II)-Cu(II)-) undergoing four-electron reduction in aqueous media and water-acetonitrile mixtures. The observed effects of solvent, pH, buffer capacity, and supporting electrolyte are discussed in the framework of a general reaction scheme involving two main routes; one of them includes protonation of intermediate species.

Magnetic alignment study of rare-earth-containing liquid crystals.

The liquid-crystalline rare-earth complexes of the type [Ln(LH)3(DOS)3]-where Ln is Tb, Dy, Ho, Er, Tm, or Yb; LH is the Schiff base N-octadecyl-4-tetradecyloxysalicylaldimine; and DOS is dodecylsulfate-exhibit a smectic A phase. Because of the presence of rare-earth ions with a large magnetic anisotropy, the smectic A phase of these liquid crystals can be easier aligned in an external magnetic field than smectic A phases of conventional liquid crystals. The magnetic anisotropy of the [Ln(LH)3(DOS)3] complexes was determined by measurement of the temperature-dependence of the magnetic susceptibility using a Faraday balance.

Adsorption and in situ scanning tunneling microscopy of cysteine on Au(111): Structure, energy, and tunneling contrasts.

The amino acid L-cysteine (Cys) adsorbs in highly ordered (3 square root of 3 x 6) R30 degrees lattices on Au(111) electrodes from 50 mM ammonium acetate, pH 4.6. We provide new high-resolution in situ scanning tunneling microscopy (STM) data for the L-Cys adlayer.

Catalytic alcohol oxidation by an unsymmetrical 5-coordinate copper complex: electronic structure and mechanism.

Density functional theory reveals the detailed mechanism of alcohol oxidation by a model copper complex, Cu(II)L, L = cis-1-(3',5'-dimethoxy-benzylideneamino)-3,5-[2-hydroxy-(3',5'-di-tert-butyl)benzylideneimino]cyclohexane. Despite the obvious structural and functional parallels between the title compound and the enzyme galactose oxidase, the details of the catalytic pathway are fundamentally different. In the enzyme, coordination of the substrate produces an active form containing a Cu(II) centre and a tyrosyl radical, the latter being responsible for the abstraction of hydrogen from the substrate.

Determination of hydrazine derivatives by flow-injection analysis with spectrophotometric detection.

Flow-injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.