JOURNAL OF THE IRANIAN CHEMICAL SOCIETY(JICS)
Year:2016 | Volume:13 | Issue:10|Papers Count:20

In the current research, nanocomposite polyethersulfone-based nanofiltration membranes were prepared by composite PAA-co-PMMA-g-ZnA nanoparticles. NF membranes were fabricated by phase inversion through casting solution technique. The effect of composite PAA-co-PMMA-g-ZnA nanoparticles concentration into the casting solution on physicochemical characteristics of membrane was studied. Scanning optical microscopy images showed uniform particle distribution for the membranes. Scanning electron microscopy images also demonstrated that membrane porosity was enhanced by increase in nanoparticles content ratio. The membrane surface 3D images showed smooth surface for the membranes filled with 0.05, 0.1 and 0.5 wt% nanoparticles. The contact angle results exhibited that membrane hydrophilicity was improved significantly by using of NPs in membrane matrix. The contact angle was decreased from 65.38° for PES membrane to 48.33° for membrane filled with 0.5 wt% nanoparticles. The water permeability was reduced initially by addition of 0.05 wt% nanoparticles into the casting solution and then increased by more nanoparticles loading rate (0.1 wt%). The water permeability was decreased again by more increase in nanoparticles loading range from 0.5 to 1 wt%. The salt rejection was improved strongly from 68.4 % for PES to 88.58 % for membrane filled with 0.5 wt% nanoparticles. The membranes mechanical strength was increased sharply from 2835.5 to 3337.3 kPa with addition of nanoparticles into the casting solution.

To clarify the significance of low-affinity Ca-binding sites in thermolysin (TLN), we compared the enzymes having bound and free weak Ca-binding sites. Binding measurements suggested that TLN comprises two strong and two weak Ca-binding sites. Far-UV CD analysis indicated that the weak sites do not affect TLN’s secondary structure. However, a slight local rearrangement due to the weak sites’ occupancy was deduced by the fluorescence measurements. Upon Ca-binding to weak sites, KM and kcat for hydrolysis of 3-(-2-furylacryloyl)-L-glycyl-L-leucine-amide were reduced about 2.8- and 1.8-fold, respectively, and kcat/KM was therefore improved about 1.5-fold. Our modeling studies suggest that the modified kinetic properties may be due to altered hinge angle between N- and C-terminal domains upon Ca-binding to the weak sites. TLN exhibited a higher temperature optimum, remarkable increase in the half-life of thermoinactivation t1/2 and enhanced remaining activity in the presence of denaturant agents in a Ca-dependent manner. In contrast, organic solvents and pH stabilities were irrelevant to the weak sites. Finally, we conclude that low-affinity sites of TLN may induce subtle changes in the local environment and modulate the enzymatic activity and thermal stability.

Polyoxometalates (POMs) are negatively charged clusters consisting of transition metals and oxygen atoms. The antiviral and antitumor activities are the dominant activities of POMs in pharmacology and medicine. Based on Co-containing Keggin polyoxomolybdate (K6[SiMo11O39Co(H2O)].nH2O), nanosized starch, and lipid-encapsulated derivatives (abbreviated as SiMo11Co, SEP and LEP, respectively) were synthesized and characterized by FT-IR spectroscopy, ICP, TG analysis, SEM and TEM images. The results show that the SiMo11Co retains its parent structure after encapsulation by starch and lipid nanoparticles. The biological activity of SiMo11Co has been evaluated by investigating its binding ability to calf thymus DNA (ctDNA), using UV–Vis absorption spectroscopy, fluorescence quenching and fluorescence Scatchard plots. The obtained results of absorption titration rule out the intercalating binding mode and propose the groove or outside stacking binding for SiMo11Co. These results were authenticated by fluorescence quenching experiments and scatchard plots. Absorption spectral traces reveal 10.21 % hyperchromism for SiMo11Co. The value of 7.6 × 103M-1 was obtained for binding constant (Kb) of SiMo11Co to ctDNA. Furthermore, the in vitro antitumor activity of SiMo11Co and nano-encapsulated forms was investigated using the 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide (MTT) assay that was carried out on two types of human cancer cells, MCF-7 (breast cancer cells) and HEK-293 (Human Embryonic Kidney). The results represent the enhancement of cell penetration and antitumor activity of SiMo11Co due to its encapsulation in starch or lipid nanoparticles. However, this observed enhancement for the lipid relative to the starch nanocapsule can be attributed to its smaller size.

A concise, efficient method to sulfonyl quinones and sulfonyl-1, 4-diols through Ir-catalyzed C–S coupling of quinones with sulfonyl chloride has been developed. Thus, this methodology proves its value as a versatile synthetic tool for a broad range of sulfonyl quinones, producing good to excellent yields.

Unsupported nanoparticles are often less stable, and usually coagulation is unavoidable during the catalytic reactions. To generate stable nanoparticles with good activity, stabilizing the surface is required. Protection has been performed by the addition of polymers or long-chain alkyl surfactants with polar functional groups that attached to the nanoparticle surface via covalent or electrostatic interactions. Alternatively, nanoparticles have been immobilized or grafted onto inorganic supports to improve their stabilization and recycling ability. In this article, the green catalytic processes and recent advances in organic transformations catalyzed by magnetically retrievable catalysts are reviewed. Prior to this, methods for the synthesis of catalysts immobilized on magnetic nanoparticles are addressed briefly.

In the present study, the profiling of 17 fatty acids (FAs) in avocado seed and pulp was investigated. The fatty acids were extracted with vortex-assisted extraction, methyl esterified and finally preconcentrated by dispersive liquid–liquid microextraction. The preconcentrated fatty acid methyl esters (FAMEs) were analyzed using gas chromatography–mass spectrometry (GC–MS) to obtain qualitative and quantitative information. The GC–MS data were analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) method to overcome general chromatographic problems such as overlapped peaks, background interference and peak shifts. The calibration data were prepared using pure analytical information obtained by MCR-ALS. The linear dynamic ranges and regression coefficients (R2) for FAMEs were in the range of 0.19-65 mg L-1 and 0.990-0.999, respectively. The relative standard deviation (RSD%) for determination of FAs in avocado seed and pulp was 0.17-8.84 and 0.64-17.93, respectively. The main FAs in the avocado pulp were: oleic acid (74.25 g Kg-1), linoleic acid (26.87 g Kg-1), palmitic acid (26.02 g Kg-1), palmitoleic acid (1.22 g Kg-1) and stearic acid (0.05 g Kg-1). And, the main FAs in the avocado seed were: linoleic acid (1.09 g Kg-1), palmitic acid (0.47 g Kg-1), oleic acid (0.33 g Kg-1), linolenic acid (0.12 g Kg-1), and palmitoleic acid (0.04 g Kg-1).

In a photochemical chamber, a sample of 27.9 mM indomethacin (IN) in methanol was exposed to a Philips 400-W UV lamp for 5 days in normal atmosphere. Four photoproducts were separated using high-performance liquid chromatography, and their structures were elucidated by various spectroscopic methods, including liquid chromatography–electrospray ionization–mass spectrometry. A reaction scheme of IN in methanol is proposed: The photochemical reaction routes occur mainly via esterification and decarboxylation, followed by oxidation with singlet oxygen to produce an aldehyde. A b-hydroxy-g-lactone was also formed through a photochemical [2 + 2] cycloaddition, and its structure was confirmed by single-crystal X-ray diffraction.

L-Cysteine-functionalized magnetic nanoparticles (LCMNP) were introduced as an efficient and magnetically separable organocatalyst for the synthesis of 9-(1H-indol-3-yl) xanthen-4-(9H)-one derivatives. This class of compounds was synthesized via a one-pot three-component coupling reaction of 2-hydroxybenzaldehyde, dimedone, and indole in the presence of catalytic amount of LCMNP under mild and green conditions. High yields, short reaction time, easy workup, using environmental friendly conditions, and magnetic reusable catalyst are the advantages of this synthetic methodology. The LCMNP catalyst was reusable in this reaction at least for 6 times without significant decreasing in its catalytic activity.

A simple one-pot synthesis of functionalized 4, 5-bis (phenylimino) -1, 3-thiazolidine-2-thione derivatives through the reaction of primary amines and carbon disulfide in the presence of N, N’-diphenyloxalimidoyl dichloride at room temperature is described.

In this work, TiO2 and doped TiO2 photocatalysts (Fe/TiO2 and Cu/TiO2) were synthesized by the sol–gel method. The main objective of this study was to investigate the influence of dopants on the structure, morphology, and activity of the catalysts in powder and immobilized states. XRF, XRD, and SEM methods were used to characterize the catalysts. The structure and phase distribution of the nanocrystalline powders were identified by XRD. Nanoparticles crystallite size and the degree of crystallinity were affected by doping. The anatase contents of catalysts were achieved as follows: TiO2 (5.89 %) < Fe/TiO2 (42.17 %) < Cu/TiO2 (70.28 %). It was indicated that the activity of the catalysts strongly depends on the anatase content. Under the same circumstances, copper-modified TiO2 exhibited a twofold higher photocatalytic activity compared with TiO2. The nanostructured catalysts were immobilized on light expanded clay aggregate (LECA) granules in order to investigate the effect of a novel support on the activity of the catalysts. Morphological changes are recognizable in the SEM images. Activity tests indicated that the best catalytic performance was assigned to Cu/TiO2/LECA. After 120 min of irradiation, 61 % degradation of phenol in synthetic wastewater was achieved. The high photocatalytic activity of Cu/TiO2/LECA confirms that LECA is as an excellent support.

Epidermal growth factor receptor (EGFR) plays an essential role in anticancer therapy. Matuzumab is an antibody for the treatment of colorectal, lung and stomach cancer. Matuzumab binds efficiently to EGFR and blocks its phosphorylation. The recent clinical successes have established application of peptides for cancer treatment. The present contribution introduces an in silico approach to design peptides based on molecular dynamics simulation (MDs) of the matuzumab-EGFR complex in water environment. Moreover, principal component analysis has been used to select multiple conformations of the complex in MDs for designing the peptides. The paratope and epitope in each conformation of the complex were determined, and the alanine scanning was used to identify the hot spots of EGFR conformers. The conformations of the peptides were optimized using PEP-FOLD server and MDs. The selected conformations were analyzed in a docking study to realize the binding site of the EGFR. Finally, pharmokinetics properties of the peptides were calculated. The designed oligopeptides were EWRSYYYWH, YYYWHNEWN, YYYWHNEWS and HNHSRNYGS with a higher affinity to the EGFR relative to the previously reported peptides. The newly designed peptides were investigated for their in vivo toxicities on rats, and all of them were non-toxic.

A streamlined Pd-catalyzed direct oxidative arylation of the pentafluorobenzene C–H bond with readily available (diacetoxyiodo) arenes has been described. Under the optimized conditions, three (diacetoxyiodo) arene derivatives were found to undergo coupling with pentafluorobenzene to furnish the substituted (pentafluorophenyl)benzenes in moderate to good yields.

Ti-HMS materials with different Si/Ti ratio (5, 10, 20 and 30) were prepared and used as the support for a palladium-containing (1 wt%) catalyst. The materials, analyzed by XRD and SEM techniques, were tested in the synthesis of some thionocarbamates from reaction of sodium O-isopropyl carbonodithioate with the corresponding amines. The best yield was obtained with 3 mmol% of the catalyst (Pd/Ti-HMS-10) in water as solvent after 10-15-h heating at 75oC. The structures of the products were identified by spectroscopy techniques such as 1H-NMR, 13C-NMR, IR and elemental analysis.

As a novel and green pretreatment technique to trace samples, polyoxyethylene cetyl ether (POELE20)–(NH4)2SO4 aqueous two-phase extraction system was coupled with high-performance liquid chromatography to analyse synchronously chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF) in chicken and pork samples. It was found that the extraction efficiency (E%) and enrichment factor (F) of the three antibiotics were influenced by the types of salts, the concentration of salt, the concentration of POELE20, system temperature and pH. The final optimal condition was as following: the phase-forming salt is (NH4)2SO4, the concentration of (NH4)2SO4 is 0.141 g mL-1, the concentration of POELE20 is 0.03 g mL−1, the temperature is 298.15 K, and the system pH is 4.5. This POELE20–(NH4)2SO4 ATPS was applied to separate and enrich three antibiotics in real sample under the optimal conditions, and it was found that the recovery was 97.20–102.00 % with a RSD of 0.61–4.85 %. The limit of detection for CAP, TAP and FF were 0.10, 0.50 and 0.50 mg kg-1, and the limit of quantitation for CAP, TAP and FF was 0.15, 1.50 and 1.50 mg kg-1. Seven times the experiments were used to verify the repeatability and veracity of this method, and the RSD for the intra-day and inter-day were 1.13–3.22 and 1.74–4.72 %.

In this paper, we describe twelve 3-hydroxy-2-naphthoic hydrazide derivatives (six thiosemicarbazides and six 1, 2, 4-triazole-3-thiones) which we have synthesized. Thiosemicarbazide derivatives were prepared by condensation reaction of 3-hydroxy-2-naphthoic hydrazide with appropriate isothiocyanates. The 1, 2, 4-triazole-3-thiones were synthesized by the cyclization reaction of corresponding thiosemicarbazide derivatives in alkaline media. All obtained compounds have been analyzed by 1H NMR and 13C NMR spectra and evaluated for in vitro antimicrobial activity against a panel of reference strains of microorganisms, including Gram-positive bacteria, Gram-negative bacteria and fungi belonging to yeasts Candida spp. Our antimicrobial screening results indicated that some of the newly obtained compounds showed high antibacterial activity, especially against Gram-positive bacteria. Among them, the activity of compounds 1, 2 and 4 was moderate to strong against staphylococci. In addition to this, compounds 1 and 2 showed two times higher activity than cefuroxime and four times higher activity than ampicillin against Bacillus cereus ATCC 10876.

In this study, a HAp/NaP nanocomposite was prepared by adding a synthesized nano-hydroxyapatite to zeolite NaP gel in the hydrothermal condition and used for the removal of lead(II) and cadmium(II) ions from aqueous solution. HAp/zeolite nanocomposite was then characterized by Fourier transform infrared spectroscopy, X-ray diffraction and Rietveld method, scanning electron microscope, energy-dispersive X-ray analysis, and surface area and thermal analyses. Results suggested that the nanocomposite crystals of HAp were dispersed onto the zeolite external surface and/or encapsulated within the zeolite channels and pores. The potential of the composite in adsorption of heavy metals was investigated by using batch experiment. The metal concentration in the equilibrium Ce (mg/g) after adsorption with nanocomposite of HAp/NaP was analyzed using flame atomic adsorption spectrometry. The adsorption experiments were carried out at pH of 3–9. The influences of contact time, initial concentration, dose, and temperature on the adsorption of lead and cadmium ions were also studied. Results show that these nanocomposites have further adsorption related to NaP and HAp. They have great potential (about 95 %) for Pb(II) and Cd(II) adsorption at room temperature. The equilibrium process was described by Frendlich, Langmuir, Temkin, and Dubinin–Radushkevich (D-R) models. The kinetics data were successfully fitted by a pseudo-second-order model. The in vitro antibacterial activity of these composites was evaluated againstBacillus subtilis (as Gram-positive bacteria) and Pseudomonas aeruginosa (as Gram-negative bacteria) and compared with standard drugs that show inhibition on bacterial growth.

Fifteen new complexes of transition metals were designed using three Schiff base ligands and aldol condensation of 2, 3-diaminopyridine with 5-R-2-hydroxybenzaldehyde (R = F, Cl, Br) in the 1:2 molar ratio. The tetradentate ligands N, N’-bis (5-R-2-hydroxybenzaldehyde) pyridine were acquired with the common formula H2 [(5-R-sal) 2py] and characterized by IR, UV–Vis spectra, 1H-NMR and elemental analysis. These ligands produce 1:1 complexes M [(5-R-sal) 2py] with Fe (III), Ni(II), Co(III), V(IV) and U(VI) metal ions. The electronic property and nature of complexes were identified by IR, UV–Vis spectra, elemental analysis, X-ray crystallography and cyclic voltammetric methods. The catalytic activity of complexes for epoxidation of styrene with UHP as primary oxidant at minimal temperature (10oC) has been planned. The spectral data of the ligands and their complexes are deliberate in connection with the structural changes which happen due to complex preparation. The electrochemical outcome has good conformability with what suggested for electronic interaction among metal center and ligand by the UV–Vis and IR measurements.

A simple and selective colorimetric biosensor was presented based on high catalysis of hemin–graphene hybrid nanosheets coupled with enzyme inhibitions. Alcohol oxidase (AO) can catalyze the oxidations of methanol to produce hydrogen peroxide (H2O2). Subsequently, the resulting H2O2 could be catalyzed to oxidize 3, 3, 5, 5-tetramethylbenzidine (TMB) and then produce a blue color reactions by using hemin–graphene hybrid nanosheets with intrinsic peroxidase-like activity. The activity of AO could be selectively inhibited by the copper ions, and therefore, the oxidase-catalyzed reactions of TMB was decreased. Fortunately, other metal ions even at 10 or 100 times copper ions concentrations showed no intensive inhibitions to the AO activity. Based on this functional materials-enzyme inhibitions system, a simple, selective and sensitive colorimetric biosensor was established to determine copper ions in soft drinks. The linear relationship was obtained from 5 nM to 1 mM, and the detections limit was 1.4 nM. The results were in good agreement with those obtained by the classic ICP-MS. It was demonstrated that the proposed method had an excellent practical perspective on the determinations of copper ions in foodstuff samples.

In the present study a glassy carbon electrode, modified with nanocomposite of gold nanoparticles/multiwalled carbon nanotubes (GNPs/MWCNTs/GCE), was used for determination of dicyclomine hydrochloride (DcCl). The results showed that synergetic effects of GNPs and MWCNTs highly improved electrochemical response and sensitivity of the sensor. The electrochemical oxidation of DcCl was investigated by cyclic voltammetry and differential pulse voltammetry. Also, scanning electron microscopy and energy dispersive x-ray spectroscopy were used to evaluate microstructure of electrochemical sensor. The effect of various experimental parameters including pH and scan rate on the voltammetric response of DcCl were investigated. Under the optimal conditions linear response was observed in range of 1.0-1.2 × 102 mmol L-1 for DcCl. The lower detection limit was found to be 0.40 µmol L-1 for DcCl. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied to the determination of DcCl in real samples.

Due to the critical role of glucose level in the diagnosis and treatment of diabetes, as well as the increasing number of diabetics, there is an overwhelming demand for developing glucose sensors. It is well acknowledged that these sensors, especially those based on glucose oxidase, have played an important role in blood glucose detection. Inspired by the attractive properties, nanomaterials, especially nanostructured carbon and metal/metal oxides, have been extensively explored to develop enzymatic glucose sensors with high sensitivity, fast response time, and satisfied stability. In this review, a brief history of glucose biosensors is firstly presented. Furthermore, we discuss the currently available fabrication possesses in the field of enzymatic glucose biosensors based on nanomaterials, focusing on the carbon-based, metal-based, and metal oxides-based nanocomposites. What is more, we discuss the challenges and attempt to give an outlook on the possible further developments.