Preparation and characterization of crosslinked alginate–CMC beads for controlled release of nitrate salt

Carboxymethyl cellulose (CMC)/sodium alginate (SA) hydrogel beads were successfully prepared by Ca²⁺ ions crosslinking followed by gamma irradiation. The factors affecting beads formation are the composition of SA in the blend and concentration of calcium chloride as a crosslinking agent. The results indicated that the addition of CMC to SA increases the swelling (%) upto (1:3) (CMC:SA) ratio. The effect of different irradiation doses (2.5, 5, and 10 kGy) on swelling (%) was studied. At low doses, swelling (%) decreases upto 5 kGy then starts to increase at 10 kGy. The degree of the swelling (%) and release (%) of ammonium nitrate salt from beads were investigated under different pH (1.2, 5 and 7). The beads were characterized by FTIR, SEM and TGA to investigate molecular structure, morphology and thermal stability of beads.     

New water-soluble forms of α-tocopherol: preparation and study of antioxidant activity in vitro

Water-soluble forms of α-tocopherol (vitamin E) possessing antioxidant activity in vitro were obtained by encapsulating in N-vinylpyrrolidone with triethylene glycol dimethacrylate polymer particles and were characterized by various physicochemical methods. Quantum-chemical modeling of a structure of α-tocopherol with the copolymer moiety and its theoretical absorption spectra modeling were carried out.     

Preparation of PLL-PEG-PLL and its application to DNA encapsulation

With the successful sequencing of Human Genome, it would be possible to cure all diseases by gene ther- apy in the near future. However, one of the major problems in gene therapy is the development of gene vectors. To date, there are two kinds of gene vectors, namely, viral and non-viral gene vectors. Viruses are widely used as vectors in gene therapy, with the trans- fection efficiency being relatively high, but they have the safety problems such as immunogenicity, non- biocompatibility and …     

Synthesis,characterization and spectroscopic study of riboflavin–molybdenum complex

A riboflavin–molybdenum [(RF)–Mo(V)] complex in powder form was synthesized and characterized by elemental analysis, UV–Vis, IR, NMR spectroscopy and X-ray diffraction. During the synthesis of this metal complex, another metal complex [Mo₂O₄(H₂O)₆]²⁺ was also synthesized and characterized. The results of X-ray diffraction study have revealed an orthorhombic cubic system for the RF–Mo complex. The steady state absorption and emission studies of RF and RF–Mo in hydrochloric acid (HCl) of varying pH were investigated. The steady state absorption with RF–Mo showed distinct changes in the absorption spectra of RF after complexation. The steady state emission results, consistent with prior reports showed fluorescence quenching in the aqueous solution of both RF and RF–Mo in HCl with the proton acting as a quencher. The Stern–Volmer constant observed was 108.79 and 98.68 for RF and RF–Mo, respectively. The binding constant for RF–Mo complex was found to be 1.201 × 10³ M⁻¹ at 298 K.     

Preparation and characterization of supported bimetallic gold–iron nanoparticles,and its potential for heterogeneous catalysis

Research on Chemical Intermediates - Bimetallic gold–iron catalysts supported on ZrO2 and TiO2 were prepared by under potential deposition. The characterization of the catalysts was performed...     

Preparation, characterization, and catalysis of mecro-catalysts

Because catalysis by metals is a surface phenomenon, many technological catalysts contain small (typically nanometre-sired) supported metal particles with a large fraction of the atoms exposed. Many reactions, such as hydrocarbon hydrogenations, are structure-insensitive, proceeding at approximately the same rates on metal particles of various sizes provided that they are larger than 1 nm and show bulk-like metallic behavior. But the catalytic properties are not known when metal particles become so small that their sizes are indium clusters consisting of several indium atoms. Here the catalytic behavior of precisely defined clusters of just four and six indium atoms on solid supports is shown. It is found that the Ir4 and Ir6 clusters differ in catalytic activity both from each other and from metallic Ir particles.     

Dicyanoanilines as potential and dual inhibitors of α-amylase and α-glucosidase enzymes: Synthesis,characterization, in vitro,in silico,and kinetics studies

The present study comprised of the synthesis of dicyanoaniline derivatives of pyridine, thiophene, furan, and substituted phenyl 1–29. All synthetic derivatives were evaluated for their potential to inhibit α-amylase and α-glucosidase enzymes. The synthesized compounds are classified into three categories A, B, and C based on variable substituents at R₁ and R_2, and the structure–activity relationship was discussed accordingly. Amongst twenty-nine derivatives, 1–29, five compounds 2, 9, 18, 23, and 24 displayed excellent inhibition against α-amylase and α-glucosidase enzymes with the IC₅₀ values ranging between 20.33 ± 0.02–25.50 ± 0.06 µM and 21.01 ± 0.12–27.75 ± 0.17 µM, respectively, while other compounds showed moderate to weak inhibition against both enzymes. Acarbose was used as the positive control in this study. The enzyme kinetic studies showed non-competitive and un-competitive types of inhibition mechanism against α-amylase and α-glucosidase enzymes, respectively. In silico studies have demonstrated the involvement of these molecules in numerous binding interactions within the active site of the enzyme.     

Comparison of the photochemical behaviors of α-tocopherol and its acetate in organic and aqueous micellar solutions

Photoionization is known to take place when α-tocopherol (TOH) is excited to the S(1) state in a polar medium. It has been previously suggested that TO(?) is formed only as a result of proton release by TOH(?+), a process that is expected to occur, in a protic solvent, on the subnanosecond time scale. Recent redeterminations of the molar absorption coefficients of e(aq)(–) (Hare J. Phys. Chem. A 2010, 114, 1766) and of TOH(?+) and TO(?) (Naqvi J. Phys. Chem. A 2010, 114, 10795) have paved the way for testing the above suggestion, even if subnanosecond time resolution is not available, since it implies the equality of [e(aq)(–)](0) and [TO(?)](0), where [···](0) denotes the concentration of the enclosed species immediately after a nanosecond laser pulse. Nanosecond pump-probe spectroscopy of TOH in aqueous micellar solution (AMS) and two organic solvents with similar polarities (acetonitrile and methanol) has revealed that prompt formation of TO(?) through dissociation (TOH + hν → TO(?) + H(?)) is not negligible even in AMS. In acetonitrile, TOH(?+) and TO(?) are formed with comparable yields, and the former converts quantitatively into TO(?) within 15 μs. In methanol, TO(?) was observed, but no evidence was found for electron ejection from TOH. Only one photoproduct, namely TO(?), could be detected when α-tocopherol acetate (TOAc) was excited to the S(1) state in several polar and nonpolar solvents; TOAc has been found to be a more efficient energy degrader than TOH.     

Preparation and characterization of the inclusion complex of baicalein with γ-cyclodextrin: an antioxidant ability study

The formation of the complex of Baicalein with γ-cyclodextrin (γ-CD) was studied by UV–Vis absorption spectroscopy, fluorescence spectra and nuclear magnetic resonance spectroscopy (NMR) in solution. The solid inclusion complex of Baicalein with γ-CD was synthesized by the co-precipitation method. The characterization of the solid inclusion complexes have been proved by infrared spectra. The formation constant (K) of complex was determined by fluorescence method. The results suggested that in different pH solutions, γ-CD has different inclusive capacity to different forms of Baicalein. γ-CD was most suitable for inclusion in neutral media. In addition, the experimental resulted confirmed the existence of 1:1 inclusion complex of Baicalein with γ-CD. Kinetic studies of DPPH? with Baicalein and γ-CD complex were done. The results obtained indicated that the Baicalein/γ-CD complex was the most reactive form. Special configuration of complex has been proposed on NMR technique.     

Preparation,characterization and application of N-methylene phosphonic acid chitosan grafted magnesia–zirconia stationary phase

A hydrophilic stationary phase (SP) was prepared through grafting N-methylene phosphonic acid chitosan on magnesia–zirconia particles (P-CTS-MgO–ZrO₂) via Lewis acid–base interaction. The resulting material was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscope and nitrogen adsorption analysis. The chromatographic performance of P-CTS-MgO–ZrO₂ was systemically evaluated by studying effect of acetonitrile content, pH and buffer concentration in the mobile phase. The results demonstrated that the novel SP provided hydrophilic, electrostatic-repulsion and ion-exchange interactions. Compared to the bare MgO–ZrO₂, P-CTS-MgO–ZrO₂ exhibited superior peak shape, reasonable resolution and reduced analysis time in separation of basic analytes. Besides, remarkable resolving power of acids, i.e. six non-steroidal anti-inflammatory drugs which failed to be eluted from the bare MgO–ZrO₂, was obtained with the theoretical plate number (N/m) of 4653–31313, asymmetry factor <1.21 and the resolution of 1.6–3.4. Finally, P-CTS-MgO–ZrO₂ SP was applied to separate monosaccharides, phospholipids and peptides. P-CTS-MgO–ZrO₂ was a promising hydrophilic SP for wide applications.     

Preparation and characterization of theβ-cyclodextrin inclusion complex with sulfafurazole

The 1 : 1 inclusion complex involving sulfafurazole (SF) and-cyclodextrin (-CD) is prepared by the freeze-drying method and characterized on the basis of its chemical analysis, thermal behavior, infrared spectrum, X-ray powder pattern and¹³C NMR spectrum in DMSO-d₆ solution. The stability constant of the inclusion complex was determined by the solubility method. The effect of cyclodextrin on the UV absorption spectrum of sulfafurazole was also observed.     

Preparation of chitosan nanoparticles by TPP ionic gelation combined with spray drying,and the antibacterial activity of chitosan nanoparticles and a chitosan nanoparticle–amoxicillin complex

Chitosan nanoparticles were prepared from chitosan with various molecular weights by tripolyphosphate (TPP) ionic gelation combined with a spray drying method. The morphologies and characteristics of chitosan nanoparticles were determined by TEM, FE-SEM and from their mean sizes and zeta potentials. The effect of chitosan molecular weight (130, 276, 760 and 1200 cPs) and size of spray dryer nozzle (4.0, 5.5 and 7.0 µm) on mean size, size distribution and zeta potential values of chitosan nanoparticles was investigated. The results showed that the mean size of chitosan nanoparticles was in the range of 166–1230 nm and the zeta potential value ranged from 34.9 to 59 mV, depending on the molecular weight of chitosan and size of the spray dryer nozzles. The lower the molecular weight of chitosan, the smaller the size of the chitosan nanoparticles and the higher the zeta potential. A test for the antibacterial activity of chitosan nanoparticles (only) and a chitosan nanoparticle–amoxicillin complex against Streptococcus pneumoniae was also conducted. The results indicated that a smaller chitosan nanoparticle and higher zeta potential showed higher antibacterial activity. The chitosan nanoparticle–amoxicillin complex resulted in improved antibacterial activity as compared to amoxicillin and chitosan nanopaticles alone. Using a chitosan nanoparticle–amoxicillin complex could reduce by three times the dosage of amoxicillin while still completely inhibiting S. pneumoniae.     

Chain termination in the oxidation of lipid models by α-tocopherol and its synthetic analog

The rate constants (k₁) and stoichiometric coefficients (f) of chain termination in the oxidation of lipid models (methyl esters of acids in the oleic series) by -tocopherol and its synthetic analog at 50°C were measured. The values of k₁ and f do not depend on the structure of the substituent R in the peroxide radical ROO of the lipid models undergoing oxidation, but the values of k₁ are determined by the conformation of the investigated phenols.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 5, pp. 441–444, September–October, 1993.     

Preparation and characterization of 2,4–D butyl ester capsule suspension for mitigation of its drift risk

A novel capsule suspension (CS) formulation was prepared by in situ polymerization of melamine formaldehyde (MF) resin which was the first time to be used to encapsulate 2,4–D butyl ester. The prepared 2,4–D butyl ester capsule suspensions were studied by ultraviolet spectrophotometer (UV), laser particle size analyzer, Optical microscopy (OM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Results showed that the encapsulation efficiency reached 93.23%, and the mean particle size (D₅₀) could be reduced to 13.80 µm by adding 4% Tween80. OM and SEM images illustrated that the core-shell structure related largely to the stability of emulsion. The spherical microcapsules possessed with rougher outer surface and the shell was about 1.5-2.0 µm thick with good methanol tolerance. Then, the formation of pre-polymer, shell material and microcapsules were revealed by FT-IR. Finally, experiments showed that the 2,4–D butyl ester CS exhibited a sustained releasing behavior in water, which could reach to 14 days.     

Inclusion complex of emodin and glycyrrhetinic acid-conjugated-β-cyclodextrin to target liver cells: synthesis,characterization, and bioactivity in vitro and in vivo

Journal of Inclusion Phenomena and Macrocyclic Chemistry - The objective of this study is to prepare a novel delivery vector, glycyrrhetinic acid -conjugated-β-cyclodextrin (GA-CD) for liver...