Poly-3-hydroxybutyrate (PHB) can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and...Poly-3-hydroxybutyrate (PHB) can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol (0.1%) was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages: a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients (ammonium, nitrate, phosphorus, copper, iron (Ⅲ), magnesium or ethylenediamine tetraacetate (EDTA)) in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle (TCA). It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% (w/w) from the initial yield of 12% (w/w) after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.展开更多
Two N-donor ligands mediated Cd(Ⅱ) coordination polymers, namely,[Cd(L)(dmpz)2]n (1) and {[Cd(L)(atr)05(H20)](H2O)}n (2) (H2L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate, dmpz = 3,5-dimethy...Two N-donor ligands mediated Cd(Ⅱ) coordination polymers, namely,[Cd(L)(dmpz)2]n (1) and {[Cd(L)(atr)05(H20)](H2O)}n (2) (H2L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate, dmpz = 3,5-dimethylpyrazole, and atr= 4-amino-l,2,4-triazole), havebeen produced. Their structures were characterized by single-crystal X-ray diffraction analysis,elemental analyses and infrared spectra. Compound 1 possesses a one-dimensional (1D) chainstructure and is finally extended into a three-dimensional (3D) supramolecular architecturethough hydrogen bonding interactions. Compound 2 features a two-dimensional (2D) networkwith 4-connected sql topology based on dinuclear Cd(Ⅱ) clusters as nodes, which is alsoassembled into a 3D supramolecular architecture through hydrogen bonding interactions.Furthermore, compounds 1 and 2 exhibit high thermal stabilities and intense fluorescent emissionin the solid, and can be explored as potential luminescent materials.展开更多
The title complex, Cl3SnCH2CH(CH3)CO2CH3L (1), was synthesized by the reaction of methyl 2-methyl-3-trichlorostannylpropionate with benzylmethylsulfoxide (L) in solid state at room temperature and readily underwent tr...The title complex, Cl3SnCH2CH(CH3)CO2CH3L (1), was synthesized by the reaction of methyl 2-methyl-3-trichlorostannylpropionate with benzylmethylsulfoxide (L) in solid state at room temperature and readily underwent transesterification into the corresponding analogues Cl3SnCH2CH(CH3)CO2RL when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of transesterification was suggested.展开更多
A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-opening polymerization of beta-butyrolactone (beta-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which wer...A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-opening polymerization of beta-butyrolactone (beta-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which were prepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (M-n = 2000, 4000 and 6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterized by IR, H-1-NMR and GPC.展开更多
A zinc(Ⅱ) compound [ZnCl2(mpcm)2](1,mpcm = methyl-3-pyridylcarbamate) was prepared by solvothermal reaction and characterized by elemental analysis,IR spectroscopy,TGA and single-crystal X-ray diffraction.The c...A zinc(Ⅱ) compound [ZnCl2(mpcm)2](1,mpcm = methyl-3-pyridylcarbamate) was prepared by solvothermal reaction and characterized by elemental analysis,IR spectroscopy,TGA and single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/n,C14H16ZnCl2N4O4,Mr = 440.58,a = 8.7893(7),b = 24.978(2),c = 9.2510(8),β = 109.318(1)°,V = 1916.6(3)3,Z = 4,θ = 1.63~25.20°,Dc = 1.527 g/cm3,μ = 1.585 mm-1,F(000) = 896,the final R = 0.0255 and wR = 0.0654 for 3080 observed reflections with Ⅰ 〉 2σ(Ⅰ).The zinc atom is four-coordinated by the pyridyl groups of two mpcm ligands and two chloride ions with a tetrahedral geometry.Two [ZnCl2(mpcm)2] subunits are held together by a pair of hydrogen bonds,forming a 32-membered macrocyclic dimer,which is further extended into a 3D tubular structure via hydrogen bonding.展开更多
A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2.6-his-(1'-phenyl-3'-methyl-5'- pyridinediacyl (H_2PMBPP) and N- cetylpyridium bromide (CPB). at an apparent ...A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2.6-his-(1'-phenyl-3'-methyl-5'- pyridinediacyl (H_2PMBPP) and N- cetylpyridium bromide (CPB). at an apparent pH=5.0 provided by a hexamethylenetetramine (5% w/w)-hydrochloric acid buffer,is propesed. The calibration graph is linear in the ran ge from展开更多
The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the...The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.展开更多
Mesenchymal stem cells(MSCs)are stromal multipotent stem cells that can differentiate into multiple cell types,including fibroblasts,osteoblasts,chondrocytes,adipocytes,and myoblasts,thus allowing them to contribute t...Mesenchymal stem cells(MSCs)are stromal multipotent stem cells that can differentiate into multiple cell types,including fibroblasts,osteoblasts,chondrocytes,adipocytes,and myoblasts,thus allowing them to contribute to the regeneration of various tissues,especially bone tissue.MSCs are now considered one of the most promising cell types in the field of tissue engineering.Traditional petri dish-based culture of MSCs generate heterogeneity,which leads to inconsistent efficacy of MSC applications.Biodegradable and biocompatible polymers,poly(3-hydroxyalkanoates)(PHAs),are actively used for the manufacture of scaffolds that serve as carriers for MSC growth.The growth and differentiation of MSCs grown on PHA scaffolds depend on the physicochemical properties of the polymers,the 3D and surface microstructure of the scaffolds,and the biological activity of PHAs,which was discovered in a series of investigations.The mechanisms of the biological activity of PHAs in relation to MSCs remain insufficiently studied.We suggest that this effect on MSCs could be associated with the natural properties of bacteria-derived PHAs,especially the most widespread representative poly(3-hydroxybutyrate)(PHB).This biopolymer is present in the bacteria of mammalian microbiota,whereas endogenous poly(3-hydroxybutyrate)is found in mammalian tissues.The possible association of PHA effects on MSCs with various biological functions of poly(3-hydroxybutyrate)in bacteria and eukaryotes,including in humans,is discussed in this paper.展开更多
Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polym...Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.展开更多
Colitis is a common disease of the colon that is very difficult to treat.Probiotic bacteria could be an effective treatment.The probiotic Escherichia coli Nissle 1917(EcN)was engineered to synthesize the ketone body(R...Colitis is a common disease of the colon that is very difficult to treat.Probiotic bacteria could be an effective treatment.The probiotic Escherichia coli Nissle 1917(EcN)was engineered to synthesize the ketone body(R)-3-hydroxybutyrate(3HB)for sustainable production in the gut lumen of mice suffering from colitis.Components of heterologous 3HB synthesis routes were constructed,expressed,optimized,and inserted into the EcN genome,combined with deletions in competitive branch pathways.The genome-engineered EcN produced the highest 3HB level of 0.6 g/L under microaerobic conditions.The live therapeutic was found to colonize the mouse gastrointestinal tract over 14 days,elevating gut 3HB and short-chain-length fatty acid(SCFA)levels 8.7-and 3.1-fold compared to those of wild-type EcN,respectively.The sustainable presence of 3HB in mouse guts promoted the growth of probiotic bacteria,especially Akkermansia spp.,to over 31%from the initial 2%of all the microbiome.As a result,the engineered EcN termed EcNL4 ameliorated colitis induced via dextran sulfate sodium(DSS)in mice.Compared to wild-type EcN or oral administration of 3HB,oral EcNL4 uptake demonstrated better effects on mouse weights,colon lengths,occult blood levels,gut tissue myeloperoxidase activity and proinflammatory cytokine concentrations.Thus,a promising live bacterium was developed to improve colonic microenvironments and further treat colitis.This proof-of-concept design can be employed to treat other diseases of the colon.展开更多
Biomimetic adsorbent named as PHBBMA was prepared from lipophilic poly-3-hydroxybutyrate (PHB) by a modified double emulsion solvent evaporation method. PHBBMA, characterized by using scanning electron microscope an...Biomimetic adsorbent named as PHBBMA was prepared from lipophilic poly-3-hydroxybutyrate (PHB) by a modified double emulsion solvent evaporation method. PHBBMA, characterized by using scanning electron microscope and nitrogen adsorption/desorption measurements, is porous spherical particles. The characterization with the thermal gravimetric analysis and differential scanning calorimetry, 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that PHBBMA preparation was a physical process without chemical reaction. The adsorption of PHBBMA for o-nitrochlorobenzene (o-NCB) was fitted better by Langmuir model than by Freundlich model, while the pseudo second-order model fitting was better than the pseudo first-order model fitting. The maximal adsorption capacity of PHBBMA for o-NCB was 57.83 mg/g at 30°C, although its specific surface area (S BET ) was only 8.45 m 2 /g. PHBBMA is a safe and environmental friendly adsorbent with high adsorption capacity because its component is innocuous and biodegradable PHB produced reusing wastes and contaminants, no byproduct can produced, and its ester and hydrocarbyl groups have strong affinity with organochlorine compounds. The further work will focus on the modification and improvement of PHBBMA in order to increase its S BET and adsorption capacity.展开更多
The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under d...The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under different crystallization conditions are proposed. It was found that the formation of banded spherulites was caused by the rhythmic crystal growth of the spherulites and lamellar twisting growth for the polymer crystallization from a thin melt film and a solution, respectively.展开更多
Cholesterol is biosynthesized by all animal cells. Beyond its metabolic role in steroidogenesis, it is enriched in the plasma membrane where it has key structural and regulatory functions. Cholesterol is thus presumab...Cholesterol is biosynthesized by all animal cells. Beyond its metabolic role in steroidogenesis, it is enriched in the plasma membrane where it has key structural and regulatory functions. Cholesterol is thus presumably important for post-injury axon regrowth, and this notion is supported by studies showing that impairment of local cholesterol reutilization impeded regeneration. However, several studies have also shown that statins, inhibitors of 3-hydroxy-3-methylglutaryl-Co A reductase, are enhancers of axon regeneration, presumably acting through an attenuation of the mevalonate isoprenoid pathway and consequent reduction in protein prenylation. Several recent reports have now shown that cholesterol depletion, as well as inhibition of cholesterol synthesis per se, enhances axon regeneration. Here, I discussed these findings and propose some possible underlying mechanisms. The latter would include possible disruptions to axon growth inhibitor signaling by lipid raft-localized receptors, as well as other yet unclear neuronal survival signaling process enhanced by cholesterol lowering or depletion.展开更多
One two-dimensional coordination polymer with a formula of {[Cd(L)(imidazole)(H2O)](H2O)}n(1) was obtained by the synthetic reactions in aqueous solution using a newly synthesized H2L(H2L = methyl-3-hydroxy...One two-dimensional coordination polymer with a formula of {[Cd(L)(imidazole)(H2O)](H2O)}n(1) was obtained by the synthetic reactions in aqueous solution using a newly synthesized H2L(H2L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate) ligand.Compound1 crystallizes in monoclinic system,space group C2/c with a = 18.3176(11),b = 8.5366(9),c =8.4152(5)A,β = 101.789(6)°,V = 2797.1(3)A^3,Dc = 1.979 g/cm^3,C(10)H(12)N2O7SCd,Mr = 416.68 F(000) = 1648,μ = 1.745 mm^-1,F(000) = 1648,the final R = 0.0323 and wR = 0.0604 for 2604 observed reflections with I 〉 2s(I).Structure analyses reveal that the compound is constructed by dinuclear Cd(Ⅱ) clusters bridged by two hydroxyl oxygens of L^2-anions,which features a two-dimensional network with 4-connected sql topology.Furthermore,the compound exhibits high thermal stability and intense fluorescent emission,and could be explored for potentia luminescent materials.展开更多
A new chromone derivative, 3-[1- (2, 4, 6-trihydroxyphenyl) 3-di-(4-hydroxyphenyl) 1-propanone-2-yl] 5,7-dihydroxy-8-di(4-hydroxyphenyl)methyl-4H-1-benzopyran-4-one, named as isomohsenone was isolated from the roots o...A new chromone derivative, 3-[1- (2, 4, 6-trihydroxyphenyl) 3-di-(4-hydroxyphenyl) 1-propanone-2-yl] 5,7-dihydroxy-8-di(4-hydroxyphenyl)methyl-4H-1-benzopyran-4-one, named as isomohsenone was isolated from the roots of Stellera chamaejasme L. together with known chamaechromone. Its structure was determined by the analysis of MS and NMR data, especially 2D NMR spectra.展开更多
BACKGROUND: Bacteria endogenously residing within the plant tissues have attracted significant attention for production of biopolyester, polyhydroxyalkanoates (PHAs). Bacillus cereus RCL 02 (MCC 3436), a leaf end...BACKGROUND: Bacteria endogenously residing within the plant tissues have attracted significant attention for production of biopolyester, polyhydroxyalkanoates (PHAs). Bacillus cereus RCL 02 (MCC 3436), a leaf endophyte of oleaginous plant Ricinus communis L. accumulates 81% poly(3-hydroxybutyrate) [P(3HB)] of its cell dry biomass when grown in mineral salts (MS) medium. METHODS: The copolymer production efficiency of B. cereus RCL 02 was evaluated in valeric acid supplemented MS medium under biphasic cultivation condition. The copolymer so produced has been compared with the P(3HB) isolated from RCL 02 in terms of thermal, mechanical and chemical properties. RESULTS: Valeric acid supplementation as co-substrate in the medium has led to the production of copolymer of 3- hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) [P(3HB-co-3HV)] with 14.6 mol% 3HV. The identity of the polymers has been confirmed by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic studies. Thermogravimetric analysis (TGA) revealed that P(3HB) and P(3HB-co-3HV) films degraded at 278.66℃ and 273.49℃, respectively. The P(3HB-co-3HV) showed lower melting temperature (165.03℃) compared to P (3HB) (170.74℃) according to differential scanning calorimetry (DSC). Incorporation of 3HV monomers decreased the tensile strength (21.52 MPa), tensile modulus (0.93 GPa), storage modulus (E') (0.99 GPa) and increased % elongation at break (12.2%) of the copolyester. However, P(3HB) showed better barrier properties with lower water vapor transmission rate (WVTR) of 0.55 g-mil/100 in2/24 h. CONCLUSION: These findings emphasized exploration of endophytic bacterial strain (RCL 02) to produce biodegradable polyesters which might have significant potential for industrial application.展开更多
Chloroplast integration and expression vector containing expression cassettes for phbB, phbA, phbC and aadA genes was constructed and bombarded into the tobacco chloroplast genome. Transplastomic plants were analyzed ...Chloroplast integration and expression vector containing expression cassettes for phbB, phbA, phbC and aadA genes was constructed and bombarded into the tobacco chloroplast genome. Transplastomic plants were analyzed with PCR and Southern blot. Their homoplastomy was also judged. Northern dot and RT-PCR analysis were employed to investigate transgene expression at transcriptional level. The results indicate that the chloroplast transformation system is compatible for poly-3-hydroxybutyrate (PHB) production.展开更多
The gene of the first key enzyme of poly-β-hydroxybutyrate synthesis, 3-ketothiolase, has been amplified and cloned from chromosomal DNA of Alcaligenes eutrophus H16 by PCR. DNA sequencing results show that phbA clon...The gene of the first key enzyme of poly-β-hydroxybutyrate synthesis, 3-ketothiolase, has been amplified and cloned from chromosomal DNA of Alcaligenes eutrophus H16 by PCR. DNA sequencing results show that phbA cloned in pBluescriptSK^+ has an identical sequence with that reported previously except for one base pair. The plant constitutive expression vector has been constructed and tobacco has been transformed in order to examine the phbA gene function and the efficiency of ctp gene product. SDS-polyacrylamide gel electrophoresis result shows that the ctp gene product could direct foreign protein into plastid efficiently and phbA gene could be translated into corresponding protein with correct size. The enzyme activity analysis of 3-ketothiolase shows that the enzyme could catalyze acetyl-CoA to form acetoacetylCoA.展开更多
基金New Century Excellent Talents in University of China(NCET-05-0358)the National Natural Science Foundation of China(20625308)
文摘Poly-3-hydroxybutyrate (PHB) can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol (0.1%) was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages: a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients (ammonium, nitrate, phosphorus, copper, iron (Ⅲ), magnesium or ethylenediamine tetraacetate (EDTA)) in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle (TCA). It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% (w/w) from the initial yield of 12% (w/w) after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.
基金supported by the National Natural Science of Foundation of China(No.21671094)
文摘Two N-donor ligands mediated Cd(Ⅱ) coordination polymers, namely,[Cd(L)(dmpz)2]n (1) and {[Cd(L)(atr)05(H20)](H2O)}n (2) (H2L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate, dmpz = 3,5-dimethylpyrazole, and atr= 4-amino-l,2,4-triazole), havebeen produced. Their structures were characterized by single-crystal X-ray diffraction analysis,elemental analyses and infrared spectra. Compound 1 possesses a one-dimensional (1D) chainstructure and is finally extended into a three-dimensional (3D) supramolecular architecturethough hydrogen bonding interactions. Compound 2 features a two-dimensional (2D) networkwith 4-connected sql topology based on dinuclear Cd(Ⅱ) clusters as nodes, which is alsoassembled into a 3D supramolecular architecture through hydrogen bonding interactions.Furthermore, compounds 1 and 2 exhibit high thermal stabilities and intense fluorescent emissionin the solid, and can be explored as potential luminescent materials.
文摘The title complex, Cl3SnCH2CH(CH3)CO2CH3L (1), was synthesized by the reaction of methyl 2-methyl-3-trichlorostannylpropionate with benzylmethylsulfoxide (L) in solid state at room temperature and readily underwent transesterification into the corresponding analogues Cl3SnCH2CH(CH3)CO2RL when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of transesterification was suggested.
文摘A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-opening polymerization of beta-butyrolactone (beta-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which were prepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (M-n = 2000, 4000 and 6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterized by IR, H-1-NMR and GPC.
基金Supported by the National Natural Science Foundation of China (No. 20872149)
文摘A zinc(Ⅱ) compound [ZnCl2(mpcm)2](1,mpcm = methyl-3-pyridylcarbamate) was prepared by solvothermal reaction and characterized by elemental analysis,IR spectroscopy,TGA and single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/n,C14H16ZnCl2N4O4,Mr = 440.58,a = 8.7893(7),b = 24.978(2),c = 9.2510(8),β = 109.318(1)°,V = 1916.6(3)3,Z = 4,θ = 1.63~25.20°,Dc = 1.527 g/cm3,μ = 1.585 mm-1,F(000) = 896,the final R = 0.0255 and wR = 0.0654 for 3080 observed reflections with Ⅰ 〉 2σ(Ⅰ).The zinc atom is four-coordinated by the pyridyl groups of two mpcm ligands and two chloride ions with a tetrahedral geometry.Two [ZnCl2(mpcm)2] subunits are held together by a pair of hydrogen bonds,forming a 32-membered macrocyclic dimer,which is further extended into a 3D tubular structure via hydrogen bonding.
基金The authors are gratelbl for financial supports IYom the National Natural Science roundation of Chinathe Educational Commiss
文摘A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2.6-his-(1'-phenyl-3'-methyl-5'- pyridinediacyl (H_2PMBPP) and N- cetylpyridium bromide (CPB). at an apparent pH=5.0 provided by a hexamethylenetetramine (5% w/w)-hydrochloric acid buffer,is propesed. The calibration graph is linear in the ran ge from
文摘The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.
基金Supported by Russian Science Foundation,No.17-74-20104
文摘Mesenchymal stem cells(MSCs)are stromal multipotent stem cells that can differentiate into multiple cell types,including fibroblasts,osteoblasts,chondrocytes,adipocytes,and myoblasts,thus allowing them to contribute to the regeneration of various tissues,especially bone tissue.MSCs are now considered one of the most promising cell types in the field of tissue engineering.Traditional petri dish-based culture of MSCs generate heterogeneity,which leads to inconsistent efficacy of MSC applications.Biodegradable and biocompatible polymers,poly(3-hydroxyalkanoates)(PHAs),are actively used for the manufacture of scaffolds that serve as carriers for MSC growth.The growth and differentiation of MSCs grown on PHA scaffolds depend on the physicochemical properties of the polymers,the 3D and surface microstructure of the scaffolds,and the biological activity of PHAs,which was discovered in a series of investigations.The mechanisms of the biological activity of PHAs in relation to MSCs remain insufficiently studied.We suggest that this effect on MSCs could be associated with the natural properties of bacteria-derived PHAs,especially the most widespread representative poly(3-hydroxybutyrate)(PHB).This biopolymer is present in the bacteria of mammalian microbiota,whereas endogenous poly(3-hydroxybutyrate)is found in mammalian tissues.The possible association of PHA effects on MSCs with various biological functions of poly(3-hydroxybutyrate)in bacteria and eukaryotes,including in humans,is discussed in this paper.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No.20060358036)
文摘Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.
基金This research was financially supported by a grant from the Chunfeng Foundation(2020Z99CFG002)of Tsinghua UniversityOther support includes the National Natural Science Foundation of China(Grant Nos.31870859,21761132013,31771886,and 31971170).
文摘Colitis is a common disease of the colon that is very difficult to treat.Probiotic bacteria could be an effective treatment.The probiotic Escherichia coli Nissle 1917(EcN)was engineered to synthesize the ketone body(R)-3-hydroxybutyrate(3HB)for sustainable production in the gut lumen of mice suffering from colitis.Components of heterologous 3HB synthesis routes were constructed,expressed,optimized,and inserted into the EcN genome,combined with deletions in competitive branch pathways.The genome-engineered EcN produced the highest 3HB level of 0.6 g/L under microaerobic conditions.The live therapeutic was found to colonize the mouse gastrointestinal tract over 14 days,elevating gut 3HB and short-chain-length fatty acid(SCFA)levels 8.7-and 3.1-fold compared to those of wild-type EcN,respectively.The sustainable presence of 3HB in mouse guts promoted the growth of probiotic bacteria,especially Akkermansia spp.,to over 31%from the initial 2%of all the microbiome.As a result,the engineered EcN termed EcNL4 ameliorated colitis induced via dextran sulfate sodium(DSS)in mice.Compared to wild-type EcN or oral administration of 3HB,oral EcNL4 uptake demonstrated better effects on mouse weights,colon lengths,occult blood levels,gut tissue myeloperoxidase activity and proinflammatory cytokine concentrations.Thus,a promising live bacterium was developed to improve colonic microenvironments and further treat colitis.This proof-of-concept design can be employed to treat other diseases of the colon.
基金supported by the National Hi-Tech Research and Development Program (863) ofChina (No. 2006AA06Z378)the National Natural Science Foundation of China (No. 20777018, 20977035)+1 种基金the National Key Technology R&D Program of China(No. 2008BAC32B06-1)the Science and Technology Plan Project of Guangdong Province, China (No.2007B030103011)
文摘Biomimetic adsorbent named as PHBBMA was prepared from lipophilic poly-3-hydroxybutyrate (PHB) by a modified double emulsion solvent evaporation method. PHBBMA, characterized by using scanning electron microscope and nitrogen adsorption/desorption measurements, is porous spherical particles. The characterization with the thermal gravimetric analysis and differential scanning calorimetry, 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that PHBBMA preparation was a physical process without chemical reaction. The adsorption of PHBBMA for o-nitrochlorobenzene (o-NCB) was fitted better by Langmuir model than by Freundlich model, while the pseudo second-order model fitting was better than the pseudo first-order model fitting. The maximal adsorption capacity of PHBBMA for o-NCB was 57.83 mg/g at 30°C, although its specific surface area (S BET ) was only 8.45 m 2 /g. PHBBMA is a safe and environmental friendly adsorbent with high adsorption capacity because its component is innocuous and biodegradable PHB produced reusing wastes and contaminants, no byproduct can produced, and its ester and hydrocarbyl groups have strong affinity with organochlorine compounds. The further work will focus on the modification and improvement of PHBBMA in order to increase its S BET and adsorption capacity.
基金Key Science Foundation of Education Ministry of China (Grant No. 207051) Key Lab Foundation of Anhui (Grant No. 2005383)
文摘The spherulitic structures and morphologies of poly-(3-hydroxybutyrate) (PHB) crystallized from a so- lution and a thin melt film were investigated in this study. The formation mechanisms of banded spherulites under different crystallization conditions are proposed. It was found that the formation of banded spherulites was caused by the rhythmic crystal growth of the spherulites and lamellar twisting growth for the polymer crystallization from a thin melt film and a solution, respectively.
文摘Cholesterol is biosynthesized by all animal cells. Beyond its metabolic role in steroidogenesis, it is enriched in the plasma membrane where it has key structural and regulatory functions. Cholesterol is thus presumably important for post-injury axon regrowth, and this notion is supported by studies showing that impairment of local cholesterol reutilization impeded regeneration. However, several studies have also shown that statins, inhibitors of 3-hydroxy-3-methylglutaryl-Co A reductase, are enhancers of axon regeneration, presumably acting through an attenuation of the mevalonate isoprenoid pathway and consequent reduction in protein prenylation. Several recent reports have now shown that cholesterol depletion, as well as inhibition of cholesterol synthesis per se, enhances axon regeneration. Here, I discussed these findings and propose some possible underlying mechanisms. The latter would include possible disruptions to axon growth inhibitor signaling by lipid raft-localized receptors, as well as other yet unclear neuronal survival signaling process enhanced by cholesterol lowering or depletion.
基金supported by the National Natural Science Foundation of China(21401097)
文摘One two-dimensional coordination polymer with a formula of {[Cd(L)(imidazole)(H2O)](H2O)}n(1) was obtained by the synthetic reactions in aqueous solution using a newly synthesized H2L(H2L = methyl-3-hydroxy-5-carboxy-2-thiophenecarboxylate) ligand.Compound1 crystallizes in monoclinic system,space group C2/c with a = 18.3176(11),b = 8.5366(9),c =8.4152(5)A,β = 101.789(6)°,V = 2797.1(3)A^3,Dc = 1.979 g/cm^3,C(10)H(12)N2O7SCd,Mr = 416.68 F(000) = 1648,μ = 1.745 mm^-1,F(000) = 1648,the final R = 0.0323 and wR = 0.0604 for 2604 observed reflections with I 〉 2s(I).Structure analyses reveal that the compound is constructed by dinuclear Cd(Ⅱ) clusters bridged by two hydroxyl oxygens of L^2-anions,which features a two-dimensional network with 4-connected sql topology.Furthermore,the compound exhibits high thermal stability and intense fluorescent emission,and could be explored for potentia luminescent materials.
文摘A new chromone derivative, 3-[1- (2, 4, 6-trihydroxyphenyl) 3-di-(4-hydroxyphenyl) 1-propanone-2-yl] 5,7-dihydroxy-8-di(4-hydroxyphenyl)methyl-4H-1-benzopyran-4-one, named as isomohsenone was isolated from the roots of Stellera chamaejasme L. together with known chamaechromone. Its structure was determined by the analysis of MS and NMR data, especially 2D NMR spectra.
文摘BACKGROUND: Bacteria endogenously residing within the plant tissues have attracted significant attention for production of biopolyester, polyhydroxyalkanoates (PHAs). Bacillus cereus RCL 02 (MCC 3436), a leaf endophyte of oleaginous plant Ricinus communis L. accumulates 81% poly(3-hydroxybutyrate) [P(3HB)] of its cell dry biomass when grown in mineral salts (MS) medium. METHODS: The copolymer production efficiency of B. cereus RCL 02 was evaluated in valeric acid supplemented MS medium under biphasic cultivation condition. The copolymer so produced has been compared with the P(3HB) isolated from RCL 02 in terms of thermal, mechanical and chemical properties. RESULTS: Valeric acid supplementation as co-substrate in the medium has led to the production of copolymer of 3- hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) [P(3HB-co-3HV)] with 14.6 mol% 3HV. The identity of the polymers has been confirmed by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic studies. Thermogravimetric analysis (TGA) revealed that P(3HB) and P(3HB-co-3HV) films degraded at 278.66℃ and 273.49℃, respectively. The P(3HB-co-3HV) showed lower melting temperature (165.03℃) compared to P (3HB) (170.74℃) according to differential scanning calorimetry (DSC). Incorporation of 3HV monomers decreased the tensile strength (21.52 MPa), tensile modulus (0.93 GPa), storage modulus (E') (0.99 GPa) and increased % elongation at break (12.2%) of the copolyester. However, P(3HB) showed better barrier properties with lower water vapor transmission rate (WVTR) of 0.55 g-mil/100 in2/24 h. CONCLUSION: These findings emphasized exploration of endophytic bacterial strain (RCL 02) to produce biodegradable polyesters which might have significant potential for industrial application.
基金This work was supported by the State "863" High-Tech Program (Grant No. 101-04-03-04)the National Natural Science Foundation of China (Grant No. 59673008).
文摘Chloroplast integration and expression vector containing expression cassettes for phbB, phbA, phbC and aadA genes was constructed and bombarded into the tobacco chloroplast genome. Transplastomic plants were analyzed with PCR and Southern blot. Their homoplastomy was also judged. Northern dot and RT-PCR analysis were employed to investigate transgene expression at transcriptional level. The results indicate that the chloroplast transformation system is compatible for poly-3-hydroxybutyrate (PHB) production.
文摘The gene of the first key enzyme of poly-β-hydroxybutyrate synthesis, 3-ketothiolase, has been amplified and cloned from chromosomal DNA of Alcaligenes eutrophus H16 by PCR. DNA sequencing results show that phbA cloned in pBluescriptSK^+ has an identical sequence with that reported previously except for one base pair. The plant constitutive expression vector has been constructed and tobacco has been transformed in order to examine the phbA gene function and the efficiency of ctp gene product. SDS-polyacrylamide gel electrophoresis result shows that the ctp gene product could direct foreign protein into plastid efficiently and phbA gene could be translated into corresponding protein with correct size. The enzyme activity analysis of 3-ketothiolase shows that the enzyme could catalyze acetyl-CoA to form acetoacetylCoA.