Dichloride Solution Research Articles

230. The Study on Chitosan Nanoparticles as New Gene Delivery System

Top of pageAbstract Object: To find a new gene delivery system with nanotechnology. Methods: 1. The preparation of chitosan nanoparticles: The PLGA in methylene dichloride solution(0.04%) was dropped in the chitosan solution solved in acetic acid solution with high speed stirring. When turned opalescent, the solution centrifuge in a low speed. The supernatant were shifted into a clean centrifuge tube and centrifuged with high speed.The white precipitation were seen at bottom of the tube. The supernatant were discarded and the precipitation were washed twice with deoinized water and kept in PBS buffer in 4|[deg]|. A little drop in clean cover glass was dried in vacuum and analyzed with scan electron microscopy. 2. Chitosan coupled with plasmids:100|[mu]|g chitosan nanoparticles were mixed with 10|[mu]|g eNOS plamids, vortex for 20s, then placed in room temperature for reaction for 2 h. 3.Transfection into cells: the non serum culture medium was added into the mixture of chitosan nanoparticles and plasmids. When the human umbilicus vascular endothelial cell fuse to 70|[sim]|80%, the mixture were added, cultured in 37|[deg]|, 5%CO2 for 5 hours in culture tank with the cells transfected with the simple plasmids as control. The nonserum medium was discarded. After the cells were washed twice with cold PBS buffer, the medium with 10% serum was added. After 48 hours in 37|[deg]|, 5%CO2, the medium was changed with non serum medium overnight. Then the supernatant was kept and analyzed with Western-blot and total RNA was extracted with Trizol reagent from the cells as RT-PCR. Results: In the pictures (enlarged 40,000|[times]|)of scan electron microscopy of, chitosan nanparticles appeared microsphere and the average size was 250nm. The cells transfected with the mixture growing in order and no obvious cell toxicity were seen. The electrophoresis picture of RT-PCR showed that target gene expression was much better in chitosan nanoparticles compared with simple gene transfected. Western-blot had similar result with RT-PCR. Conclusion: The chitosan nanoparticles can be used as a new gene delivery system.

Magnesium dicarboxylates: First structurally characterized oxydiacetate and thiodiacetate magnesium complexes

Novel magnesium oxydiacetate and thiodiacetate complexes, [{Mg(oda)(H 2O) 2} · H 2O] n ( 1) ( oda = O ( CH 2 COO ) 2 2 - ) and [Mg(tda)(H 2O) 3] · H 2O ( 2) ( tda = S ( CH 2 COO ) 2 2 - ) , were synthesized from the reaction of aqueous solutions of magnesium dichloride with a 1:1 mixture of Na 2CO 3 and oxydiacetic acid or thiodiacetic acid, respectively. Complex 1 is a one-dimensional polymer with a planar bridging oxydiacetate ligand in a meridional disposition, whereas 2 is a monomer containing the typical tridentate thiodiacetate ligand with a facial configuration.

Thiodiacetate cobalt(II) complexes: Synthesis, structure and properties

The novel cobalt thiodiacetate complex [Co(tda)(H 2O)] n ( 1a) ( tda = S ( CH 2 COO ) 2 2 - ) was synthesized from the reaction of aqueous solutions of cobalt dichloride with a 1:1 mixture of Na 2CO 3 and thiodiacetic acid. A second isomer was also obtained occasionally and identified as complex [Co(tda)(H 2O) 3] ( 1b). The reaction of 1a with 2,2′-bipyridine (bipy) gave compound [Co(tda)(bipy)(H 2O)] · 4H 2O ( 2), which has been structurally characterized and represents, to our knowledge, the first X-ray determination of a thiodiacetate–cobalt complex. The coordination is monomeric pseudo-octahedral as determined by the typical tridentate thiodiacetate ligand with a facial configuration, the chelate bipy ligand and one water molecule. Conversely, the interaction of bis(2-pyridyl)ketone with 1a afforded the compound [Co{OC(OH)(2-pyridyl) 2} 2] +[Htda] − · 3H 2O ( 3), as confirmed from an X-ray analysis. The bis(2-pyridyl)ketone ligand is hydrolyzed with a concomitant oxidation of the metal to Co(III), a process which has been previously described, while the tda ligand, displaced from the coordination sphere, is monoprotonated and acts as counterion.

Synthesis of Diindeno-Fused 4H-Cyclopenta[def]phenanthren-4-ones and Related Compounds via Benzannulated Enediynyl Propargylic Alcohols

[reaction: see text] Treatment of propargylic diols 5-7 with thionyl chloride promoted a cascade sequence of reactions leading to dichlorides 10-12 and, after reduction with tributyltin hydride, the diindeno-fused 4H-cyclopenta[def]phenanthrenes 13-15 in a single operation. Hydrolysis of 13 and 14 furnished 4H-cyclopenta[def]phenanthren-4-ones 16 and 17, respectively. Air oxidation of an alkaline solution of dichloride 11 produced diketone 18.

Organometallic Anticancer Agents: Cellular Uptake and Cytotoxicity Studies on Thiol Derivatives of the Antitumor Agent Molybdocene Dichloride

The effect of aqueous solubility, charge, and lability of four thiol derivatives of the antitumor metallocene molybdocene dichloride (Cp(2)MoCl(2)) on the cell uptake and cytotoxicity against V79 Chinese hamster lung cells has been determined. Addition of 4-thiol-2,3,5,6-tetrafluorobenzoic acid, 1-thio-beta-d-glucose, and 1-thio-2,3,4,5-tetraacetyl-beta-d-glucose to aqueous solutions of molybdocene dichloride afforded the corresponding metallocenes in which the deprotonated thiols are coordinated to the metal center. These metallocenes were studied, along with the previously reported glutathione derivative Cp(2)Mo(GS)(2), which has been proposed to be formed from molybdocene dichloride in blood plasma. In contrast to Cp(2)MoCl(2) which rapidly loses the chloride ligands to form a positively charged aquated complex at pH 7, the thiol derivatives are stable to ligand hydrolysis in 50 mM salt at 37 degrees C for 24 h. Cytotoxicity values determined by a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay gave an IC(50) value of 350 microM for molybdocene dichloride with V79 cells, with similar values obtained with human breast MCF-7 (620 microM) and ovarian 2008 (700 microM) cell lines. The water-soluble thiol derivatives were not cytotoxic, while the acetylated sugar derivative was insoluble in water or aqueous dimethyl sulfoxide. Cell uptake experiments in which the molybdenum content in cells treated with each metallocene for 24 h was measured by graphite furnace atomic absorption spectroscopy showed that the fluorinated aromatic derivative was most efficiently transported into cells, followed by molybdocene dichloride, with the lowest uptake observed for Cp(2)Mo(GS)(2) and the glucose derivative. The cell uptake results do not correlate with overall charge of the complexes or the measured IC(50) values. The distinct cytotoxicity and cell uptake profiles of Cp(2)MoCl(2) compared with Cp(2)Mo(GS)(2) show that while rapid coordination of Cp(2)MoCl(2) to glutathione occurs in water at pH 7, significant deactivation of molybdocene dichloride by conversion to Cp(2)Mo(GS)(2) does not occur in cells.

Synthesis, characterization and structure of metallocene dicyanamide complexes

The bis(cyclopentadienyl) complexes [Cp 2Ti(dca)] 2O and Cp 2V(dca) 2 (dca = dicyanamide) have been prepared by reaction of sodium dicyanamide with aqueous solution of titanocene dichloride and vanadocene dichloride, respectively. The X-ray structure analyses of both complexes confirmed monodentate coordination of dicyanamide ligand through the terminal nitrogen atom of cyano group.

Tris(pyrazol-1-yl)methane (Tpm)

The title compound, C10H10N6, was crystallized from a methylene dichloride solution. Tpm has gained much attention of late as a neutral scorpionate ligand analogue of hydro­tris­(pyrazol-1-yl)­borate. We report here the structure of the free Tpm ligand, which shows a structure typical of a tripodal neutral ligand. The compound crystallizes in a chiral space group despite the fact that it is achiral, ideally C3v.

Theory of capillary formation in alginate gels

The formation of capillaries in alginate gel is a dissipative process coupled with hydrodynamic flow in the immediate neighborhood of the front of gel formation. The hydrodynamic flow is due to the contraction of the alginate chains resulting from the crosslinking reaction. As shown earlier, capillary formation only occurs above a critical value of the contraction velocity. In this paper a complete theoretical model of the ratio of the actual to the critical contraction velocity is presented. The theoretical predictions are compared with experimental data for the formation of copper alginate gel from solutions of sodium alginate and copper dichloride. The ratio of the actual to the critical contraction velocity is described as a function of the bulk concentrations, the diffusion coefficients, the properties of the alginate molecules and the rate constant of copper alginate complex formation. For capillary formation to occur, the rate constant must be neither too small nor too large. In agreement with experimental data the model predicts that capillary formation is restricted to a finite time interval and will not take place if the copper concentration is too low or the alginate concentration is too high.

Nano-size particles of palladium intermetallic compounds as catalysts for oxidative acetoxylation

Fine particles of palladium containing intermetallic compounds (IMCs) were prepared on the surface of silica gel and their catalytic properties for the oxidative acetoxylation of toluene and 1,3-butadiene (BD) were investigated. Intermetallic compounds were prepared on silica by the successive impregnation using aqueous solutions of palladium dichloride and a compound of the second metal. Through the reduction in hydrogen at proper temperatures, particles of Pd 5Ge, Pd 2Ge, PdZn, Pd 5Ga 2, PdTe, PdIn, Pd 3Bi, Pd 3Pb, PdCd and Pd 3Tl were formed with crystallite diameters below 7 nm. PdFe particles were obtained by chemical vapor deposition (CVD) of ferrocene on Pd/SiO 2 and the subsequent hydrogen treatment. The catalytic properties of these supported intermetallic compounds were examined for the oxidative acetoxylation reactions. In the case of toluene acetoxylation, the high yield of benzyl acetate (BA) was obtained on Pd 3Bi/SiO 2, Pd 3Pb/SiO 2, PdCd/SiO 2 and Pd 3Tl/SiO 2, while Pd/SiO 2 predominantly catalyzed the total oxidation into carbon dioxide. In the case of 1,3-butadiene acetoxylation, Pd 3Tl/SiO 2 gave a high yield of 1,4-diacetoxy-2-butene.

Unprecedented conversion of triethylamine and disulfur dichloride into a thienopentathiepin and a heptathiocane.

[reaction: see text] In a remarkable cascade reaction, triethylamine is converted into the thienopentathiepin 2a and the heptathiocane 3a by a preequilibrated solution of disulfur dichloride and DABCO in chloroform.

Spectrophotometric readout for an alanine dosimeter for food irradiation applications

The alanine–electron spin resonance (EPR) readout system is well known as a reference and transfer dosimetry system for the evaluation of high doses in radiation processing. The high cost of an EPR/alanine dosimetry system is a serious handicap for large-scale routine application in irradiation facilities. In this study, the use of a complex produced by dissolving irradiated l-alanine in 1,4-phenyl diammonium dichloride solution was investigated for dosimetry purposes. This complex—having a purple colour—has an increasing absorbance with increasing dose in the range of 1–20 kGy. The applicability of spectrophotometric evaluation was studied by measuring the absorbance intensity of this complex at 360 and 505 nm, respectively. Fluorimetric evaluation was also investigated by measuring the emission of the complex at 435 nm as a function of dose. The present method is easy for routine application. The effect of the dye concentration as well as the suitable amount of irradiated alanine has been studied. With respect to routine application, the stability of the product complex after its formation was also investigated.

Poly(vinyl chloride)-g-poly(2-methyl-1,5-hexadiene): PVC fitted with multiple allyl groups

The objective of this research was to obtain poly(vinyl chloride) (PVC) backbone fitted with multiple allyl (-CH2CH=CH2) functions. We attained this objective by the carbocationic grafting of 2-methyl-1,5-hexadiene (CH2=C(CH3)CH2CH2CH=CH2, MeHD) from PVC. Experimentally, grafting was mediated by adding Et2AlCl to PVC/MeHD mixtures in methylene dichloride solutions in the −50 to −80 °C range. The structure and molecular weight of PVC-g-PMeHD were characterized by NMR spectroscopy and GPC, respectively. Our technique readily yields PVCs carrying up to ∼8 allyl groups per backbone.

Synthesis of platinum complexes with η 4-C 5Me 4(CF 3)H ligand. X-ray structure of [Pt(η 4-C 5Me 4H 2)Cl 2] and [Pt{η 4-C 5Me 4(CF 3)H}(η 5-C 5H 5)]PF 6

Reaction of isomeric mixture of 1,2,3,4-tetramethyl-5-(trifluoromethyl)cyclopentadiene with Zeise's salt dimer gave the only isomer [Pt{η 4-C 5Me 4(CF 3)H}Cl 2] ( 1) bearing CF 3 group exo to sp 3 carbon atom in a high yield. An attempt to prepare 1 by reaction of K 2PtCl 4 with C 5Me 4(CF 3)H using hydrochloric solution of tin dichloride as a catalyst unexpectedly resulted in a formation of [Pt(η 4-C 5Me 4H 2)Cl 2] ( 2). The X-ray structure of compound 2 is presented. Reactions of 1 with AgBF 4 in the presence of three different cyclopentadienes C 5R 1 4(R 2)H (R 1=R 2=H; R 1=R 2=Me; R 1=Me, R 2=CF 3) were studied. Crystal structure of complex [Pt{η 4-C 5Me 4(CF 3)H}(η 5-C 5H 5)]PF 6 ( 3) resulted from the reaction with cyclopentadiene was determined. When C 5Me 4(CF 3)H is used the reaction yields [Pt{η 4-C 5Me 4(CF 3)H}{η 5-C 5Me 4(CF 3)}]BF 4 ( 4) unstable in solutions. Reaction with pentamethylcyclopentadiene led to complex [Pt(η 4-C 5Me 5H)(η 5-C 5Me 5)]BF 4 ( 5) and no complexes with CF 3 containing ligands were obtained.

Influence of Water on the Cationic Polymerisation of 2-Ethenylfuran by Trifluoroacetic Acid in Methylene Dichloride

This paper reports the effect of water on the kinetics and mechanism of the heterogeneous polymerization of 2-ethenylfuran initiated by trifluoroacetic acid in methylene dichloride solution. The structure of the resin, kinetics and mechanism of reactions depend on the experimental conditions. Furthermore, a change from second to first kinetic order as the monomer concentration decreased is discussed. The polymers obtained were characterized and did not differ from those obtained for the polymerization of 1(2-furyl)1-ethanol. In a water/methylene dichloride heterogeneous mixture with a volume ratio of ≥1/45, the possibility of ionic centers can be ruled out and the polymerisation should be induced by polarised esters. A mechanism of polymerisation was proposed.

Cationic grafting of olefins from PVC: The effect of reaction conditions

The cationic grafting of isobutylene, styrene, α-methylstyrene, and β-pinene from a poly(vinyl chloride) (PVC) backbone was investigated. Grafting-from was induced by Et2AlCl in 1,2-dichloroethane and methylene dichloride solutions from 20 to −70 °C. The effects of temperature and proton trap [2,6-di-tert-butylpyridine (DtBP)] on grafting-from efficiency (Geff), extent of grafting, branch length (molecular weight), and number of branches per PVC molecule were determined. Reducing the temperature invariably increased the Geff and the molecular weight of polyisobutylene, polystyrene, poly(α-methylstyrene), and poly(β-pinene) branches attached to PVC. The magnitude of the effects was different with the various olefins and depended on the reaction conditions. The effect of DtBP was examined in the 5 × 10−4–4 × 10−3 mol/L range. By increasing the DtBP concentration the Geff increased; however, the number-average molecular weight of the grafted branches decreased. The lengths of the grafted branches can be controlled, and Geff's close to 100% were obtained. The fact that the proton trap reduced the molecular weights of grafted branches suggests that besides proton scavenging, DtBP may also abstract protons from the growing carbenium ion site. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1675–1680, 2001

Influence of 2,6-Di-tert-butyl-4-methylpyridine on the Polymerization of Indene Initiated with Cumyl Chloride/Tin Tetrachloride

The controlled polymerization of indene initiated with cumyl chloride and tin tetrachloride in methylene dichloride solution shows first-order kinetics with respect to SnCl4, which implies the existence of simple equilibria for ionization and dissociation, contrary to the case of TiCl4. Experiments in the presence of a hindered base (2,6-di-tert-butyl-4-methylpyridine) allowed to estimate the propagation rate constant for paired and unpaired ions in the range of 5 × 104−105 L mol-1 s-1 at −40 °C. A fast initial polymerization, which takes place in the absence of base, and is suppressed by the base, is attributed to the larger dissociation constant for the Cum+,SnCl5- ion pairs than for the polyindenyl ones, yielding a transitory excess of free ions. The hindered base suppresses the formation of free ions, may act as a proton trap in the case of zero order transfer, and may also be involved in bimolecular termination.

Application of the polyamine putrescine increased yield of ‘Mauritius’ litchi (Litchi chinensis Sonn.)

SummaryDuring the last six years, we have studied the effect of putrescine, applied at the beginning of female bloom, on ‘Mauritius’ fruit yield. Concentrations required varied from year to year, but consistent increases were obtained with 5.10‒5,2.5.10‒4 and 5.10‒4 M putrescine. In 1994, inflorescences were immersed in a putrescine dichloride (putrescine) solution at 5.10‒6, 5.10‒5,5.10‒4, or 5.10"3 M. The two intermediate concentrations significantly increased the number of fruits per panicle, by about 100%. In 1995, individual trees were sprayed with putrescine at 1.10‒5, 5.10‒5, 2.5.10‒4, 5.10"4, or 5.10‒3 M. The best effect was obtained at the three intermediate concentrations. In 1996, individual trees were sprayed with putrescine at 5.10‒5, 2.5.10‒4, or 5.10‒4 M (8, 40 or 80 ppm, respectively). A significant yield increase, of about 50%, was obtained with all treatments. In 1997 and 1998, large-scale trials were conducted, using 40 ppm putrescine. In 1997, yield was increased by 102%, from 4.1 to 8.31 ha‒1. In 1998, yield was increased by 60%, from 7.2 to 11.51 ha‒1. Weight of individual fruit was not significantly affected in any of the trials.

Reactions of grignard reagents with bis- or mono-phosphonium ions in situ generated from Bu3P and dicarboxylic acid dichlorides or omega-ethoxycarbonyl alkanoyl chlorides as a novel method to obtain diketones and ketoesters.

Reactions of Grignard reagents with bis-phosphonium or mono-phosphonium ions in situ generated from BusP and ClCO(CH2)nCOCl (5) or ClCO(CH2)nCO2Et (13) as a tool for preparation of symmetrical diketones or ketoesters were examined. Addition of Bu3P (2.0 eq) to a THF solution of 5 (n=2) at -40 degrees C followed by addition of n-BuMgCl (2.0 eq) gave the corresponding diketone in good yield. When a mixture of BusP and the Grignard reagent (2.0 eq each) was added to the dichloride solution at the same temperature, a better result was obtained. The latter method not with PhMgBr but with n-BuMgCl or MeMgBr was shown to be useful for preparation of symmetrical alkanediones and keto alkanoates from various 5 (n=2-6) and 13 (n=2 or 3), respectively. For synthesis of alpha-diketones or alpha-ketoesters, only PhMgBr entered the reaction, although the yields were not satisfactory. Addition of a mixture of Bu3P (2.0 eq), MeMgBr (1.0 eq) and BuMgCl (1.0 eq) to a THF solution of 5 (n=4) at -40 degrees C afforded a mixture of 2,7-undecanedione and the corresponding two symmetrical diketones, with the yield of the unsymmetrical diketone being 36%.

3,5-Bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]nitrobenzene

A solution of 5-nitroisophthaloyl dichloride (1) [1] (3.92 g, 15.8 mmol) and 4-tert-butylbenzhydrazide (2) [2] (6.08 g, 31.6 mmol) in CHCl3 (70 mL) was heated to reflux for 12 h.[...]

Conformational transition of nanoparticles composed of poly(γ-benzyl l-glutamate) as the core and poly(ethylene oxide) as the shell

Diblock copolymers composed of poly(γ-benzyl l-glutamate) (PBLG) as the hydrophobic component and poly(ethylene oxide) (PEO) as the hydrophilic component were obtained by the polymerization of γ-benzyl l-glutamate N-carboxyanhydride, initiated by the primary amino end group of the α-methoxy-ω-amino PEO. Nanoparticles are formed from an organic solution of the block copolymers by the diafiltration method. From the NMR measurement of the nanoparticle in water, the PEO segments in the copolymer extend out as the shell from the nanoparticle core into the aqueous environment. From circular dichroism measurements in ethylene dichloride solution, it was found that the polypeptide block exists in the α-helical conformation and adopts right-handed helix sense, as in PBLG homopolymer. However, the helix sense of PBLG in the copolymer nanoparticles prepared from organic solvent depends on the PEO content in the copolymer and the nature of solvent.