Adsorption of human serum albumin (HSA) onto colloidal TiO2 particles, Part I

The adsorption of human serum albumin (HSA) onto colloidal TiO2 (P25 Degussa) particles was studied in NaCl electrolyte at different solution pH and ionic strength. The HSA-TiO2 interactions were studied using adsorption isotherms and the electrokinetic properties of HSA-covered TiO2 particles were monitored by electrophoretic mobility measurements. The adsorption behavior shows a remarkable dependence of the maximum coverage degree on pH and was almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP approximately 4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions (at pH values far away from the HSA IEP and TiO2 PZC) were observed. Structural and electrostatic effects can explain the diminution of HSA adsorption under these conditions, assuming that protein molecules behave as soft particles. Adsorption reactions are discussed, taking into account acid-base functional groups of the protein and the surface oxide in different pH ranges, considering various types of interactions.     

Large-Scale Production and Purification of Ascochyta caulina Phytotoxins and a New HPLC Method for their Analysis

The toxins produced by Ascochyta caulina have potential as a natural herbicide. They are three basic non-protein amino acids. Considering the need to optimize and maximize their production by fermentation in order to obtain large amounts of toxins, a new, simple, and inexpensive HPLC method was developed. This new process allows rapid evaluation of the toxin content in the fungal culture filtrates. The simplification and scaling up of the entire process include a single-step purification of the filtrates by cationic exchange chromatography by using a reusable resin with a high exchange capacity and distilled water and dilute ammonia as eluents. This process allows the fast and easy purification of large volumes of filtrates and the harvest of large amounts of a mixture containing the three pure toxins. These methods are described here and their potential to be scaled up to a pre-industrial level is discussed.     

Complexation of polyacrylates by Ca2+ ions. Time-resolved studies using attenuated total reflectance Fourier transform infrared dialysis spectroscopy

The attenuated total reflectance Fourier transform infrared dialysis technique is introduced for the time-resolved investigation of the binding processes of Ca2+ to polyacrylates dissolved in water. We observed transient formation of intermediates in water with various types of coordination of the carboxylate group to Ca2+ throughout the complexation steps. Time-resolved changes in the spectra were analyzed with principal component analysis, from which the spectral species were obtained as well as their formation kinetics. We propose a model for the mechanisms of Ca2+ coordination to polyacrylates. The polymer chain length plays an important role in Ca2+ binding.     

A Fast and Effective Method for Packing Nano-LC Columns with Solid-Core Nano Particles Based on the Synergic Effect of Temperature, Slurry Composition, Sonication and Pressure

Nano-LC columns of different lengths (14–35 cm), 75 μm i.d., were packed with solid-core C18 particles using a conventional HPLC system at low pressure (375 bar) and without expensive tools and fittings. Solid-core particles consist of a solid, non-porous core surrounded with a shell of a porous layer with a very narrow particle size distribution. This geometry allows a faster diffusion of the analytes compared to porous particles, reducing the C term of the Knox plot. Different slurries of packing material were evaluated and tested. The packing procedure was carried out at room temperature and at 70 °C to evaluate the influence of this parameter on the overall process. The synergic action of pressure, temperature and sonication contributed to columns of various lengths in the packing process. The columns were tested at room temperature taking into account the following parameters: Knox plots, specific permeability and peak capacity. Reduced heights of theoretical plates, h, ranged between 3.8 and 5.1 at ν between 2 and 6. An LC-MS test was carried out with a Direct-EI LC-MS instrument.     

Synthesis and In Vitro Characterization of Selective Cannabinoid CB2 Receptor Agonists: Biological Evaluation against Neuroblastoma Cancer Cells

1,8-naphthyridine-3-carboxamide structures were previously identified as a promising scaffold from which to obtain CB2R agonists with anticancer and anti-inflammatory activity. This work describes the synthesis and functional characterization of new 1,8-naphthyridin-2(1H)-one-3-carboxamides with high affinity and selectivity for CB2R. The new compounds were able to pharmacologically modulate the cAMP response without modulating CB2R-dependent β-arrestin2 recruitment. These structures were also evaluated for their anti-cancer activity against SH-SY5Y and SK-N-BE cells. They were able to reduce the cell viability of both neuroblastoma cancer cell lines with micromolar potency (IC₅₀ of FG158a = 11.8 μM and FG160a = 13.2 μM in SH-SY5Y cells) by a CB2R-mediated mechanism. Finally, in SH-SY5Y cells one of the newly synthesized compounds, FG158a, was able to modulate ERK1/2 expression by a CB2R-mediated effect, thus suggesting that this signaling pathway might be involved in its potential anti-cancer effect.     

Assessment of the Arsenic Removal From Water Using Lanthanum Ferrite

The catalytic performance of a perovskite-type lanthanum ferrite LaFeO₃ to remove arsenic from water has been investigates for the first time. LaFeO₃ was prepared by citrate auto-combustion of dry gel obtained from a solution of the corresponding nitrates poured into citric acid solution. Kinetic studies were performed in the dark with As(V) and in the dark and under UV-C irradiation at pH 6–7 with As(III) (both 1 mg L⁻¹), and As : Fe molar ratios (MR) of 1 : 10 and 1 : 100 using the LaFeO₃ catalyst. As(V) was removed from solution after 60 min in the dark in 7 % and in 47 % for MR=1 : 10 and MR=1 : 100, respectively, indicating the importance of the amount of the iron material on the removal. Oxidation of As(III) in the dark was negligible after 60 min in contact with the solid sample, but complete removal of As(III) was observed within 60 min of irradiation at 254 nm, due to As(III) photooxidation to As(V) and to As(III) sorption to a minor extent. Morphological and microstructural studies of the catalyst complement the catalytic testing. This work demonstrates that LaFeO₃ can be used for the removal of As(III) from highly arsenic contaminated water.     

Decay and other estimates for a semi-infinite magnetoelastic cylinder: Saint-Venant''s principle

An analogue of the well known Toupin's version of Saint-Venant's principle is proved for a semi-infinite magnetoelastic cylinder under very mild assumptions on the asymptotic behaviour of the Dirichlet integral of the magnetic field and of the elastic energy. With regard to the elastic fields, we assign on the base either the stress or the displacement vector while we assume that the lateral surface is either traction free or held fixed at zero displacement. We make use of the first Korn inequality and estimate the total energy of the conductor in terms of the data for all the problems considered.     

Iodine(III)-promoted ring contraction of 1,2-dihydronaphthalenes: a diastereoselective total synthesis of (+/-)-indatraline

[reaction: see text] A new approach for the synthesis of (+/-)-indatraline, which is a 3-phenyl-1-indanamine that displays several biological activities, is described. The strategy features as the key step a diastereoselective ring contraction of a 1,2-dihydronaphthalene promoted by PhI(OTs)OH, to construct the indan ring system. The oxidative rearrangement of other 1,2-dihydronaphthalenes was also investigated, generalizing this method to obtain indans.     

Poly(ether ester amide) microspheres for protein delivery: influence of copolymer composition on technological and biological properties

The production of PEEA microspheres with potential as carriers for protein oral delivery is described. PEEAs with different hydrophilicity were synthesized and characterized. Experiments showed that an increase in copolymer hydrophilicity gave particles less prone to cell interaction. BSA release profiles from PEEA microspheres demonstrated that an increase in polymer hydrophilicity was useful in limiting protein burst and modulating drug delivery rate by increasing PEEA degradability. These results show that fine-tuning of the hydrophilic/hydrophobic properties of PCL is essential for the formulation protein-loaded microspheres with specific properties.     

A comprehensive electronic structure description of a biscyanotetraazacobalt(III) macrocyclic complex

Molecular modeling and a detailed spectroscopic characterization of the macrocyclic complex [Co(meso)(CN)(2)](+) (meso = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) is herein presented. Structural, electronic and vibrational features are discussed and assignments were proposed on the basis of semi-empirical (molecular mechanics (MM+), ZINDO/S and PM3) quantum-mechanics calculations. The energy and the composition of the molecular orbitals of the complex were calculated and a quantitative diagram was constructed. The simulated UV-vis spectrum exhibited a reasonably good accordance with the experimental one and fully assignments of seven bands were made. An optimized configuration of the complex showed a strong cobalt-cyanide axial bond in agreement with the major contribution of the cyanide to the composition of the molecular orbitals in contrast to a discrete participation of the macrocyclic meso to the ground state of the complex.