门多萨假单胞菌DS04-T对Poly(3HB-co-4HB)的降解研究

考察了门多萨假单胞菌DS04-T对Poly(3HB-co-4HB)的降解行为。以Poly(3HB-co-4HB)为唯一碳源,分别考察培养时间、培养温度、摇床转速、装液量、培养基起始pH值、接种量等因素对降解行为的影响。结合正交试验优化获得了菌株的最佳产酶条件:培养时间为28h,培养温度为30℃,培养基初始pH值为7.3,摇床转速为150r/min,培养基装液量为120mL(250mL三角瓶),接种量为1.5%(体积分数),此条件下菌株对Poly(3HB-co-4HB)的降解酶活力可达(26.2±0.7)U.mL-1。

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) supports adhesion and migration of mesenchymal stem cells and tenocytes

AIM: To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair. METHODS: The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal stem cells (hMSC) was explored by monitoring adhesive characteristics on films of varying weight/volume ratios coupled to a culture atmosphere of either 21% O2 (air) or 2% O2 (physiological normoxia). The diameter and stiffness of PHBHHx films was established using optical coherence tomography and mechanical testing, respectively. RESULTS: Film thickness correlated directly with weight/volume PHBHHx (r2 = 0.9473) ranging from 0.1 mm (0.8% weight/volume) to 0.19 mm (2.4% weight/volume). Film stiffness on the other hand displayed a biphasic response which increased rapidly at values > 1.6% weight/volume. Optimal cell attachment of rT required films of ≥ 1.6% and ≥ 2.0% weight/volume PHBHHx in 2% O2 and 21% O2 respectively. A qualitative adhesion increase was noted for hMSC in films ≥ 1.2% weight/volume, becoming significant at 2% weight/volume in 2% O2. An increase in cell adhesion was also noted with ≥ 2% weight/volume PHBHHx in 21% O2. Cell migration into films was not observed. CONCLUSION: This evaluation demonstrates that PHBHHx is a suitable polymer for future cell/polymer replacement strategies in tendon repair.

Effect of poly(3-hydroxyalkanoates) as natural polymers on mesenchymal stem cells

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.

A Study on Preparation and Use of Nano Poly Pyrrole and Nano Poly (3,4-Ethylenedioxythiophene) Coated Glassy Carbon Electrode For The Determination of Antihistamine in Pharmaceutical and Urine Sample

Pheniramine maleate (PA), an antihistamine, was determined by Differential Pulse Stripping voltammetry using nano polypyrrole (Ppy) and nano poly(3,4-ethylenedioxythiophene) (PEDOT) modified glassy carbon electrodes. The cyclic voltammetric behavior of pheniramine was studied in aqueous acidic, neutral and alkaline conditions. One well-defined oxidation peak was observed in the cyclic voltammograms at all pHs. The influence of pH, scan rate and concentration revealed irreversible electron transfer and the oxidation was diffusion controlled adsorption. The SEM analysis confirmed good accumulation of PA on the electrode surface. A systematic study of influence of various experimental parameters that affect the stripping voltammetric response was carried out and the maximum peak current conditions were arrived at. Calibration was made under maximum peak current conditions. The range of study was 0.05 to 0.4 μg/mL on Ppy/GCE and 0.025 to 0.4μg/mL on PEDOT/GCE and the lower limit of determination were 0.035μg/mL on Ppy/GCE and 0.016μg/mL on PEDOT/GCE. The suitability of the method for the determination of PA in pharmaceutical preparations and urine samples was also ascertained.

Annealed Treatment Effect in Poly（3-hexylthiophene）：Methanofullerene Solar Cells

Polymer photovoltaic devices based on poly（3-hexylthiophene） （P3HT） ： [6,6]-phenyl-C61-butyricacid methyl ester （PCBM） 1：1 weight-ratio blend are reported. The effects of various annealing treatments on the device performance are investigated. Thermal annealing shows significant improvement of the device performances. For devices at 130℃ annealing, maximum power conversion efficiency （PCE） of 3.3% and All factor up to 60.3% is achieved under air mass 1.5, 100 m W/cm^2 illumination. We discuss the effect of thermal annealing by the results of ultraviolet-visible absorption spectroscopy （UV-vis）, dark current-voltage curve, atomic force microscopy （AFM）.

DOPING LEVEL INCREASE OF POLY(3-METHYLTHIOPHENE)FILM DURING ELECTROCHEMICAL POLYMERIZATION PROCESS

The Raman spectra of poly(3-methylthiophene) (PMeT) films with different thicknesses, which have been electrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3-methylthiophene in boron trifluoride diethyl etherate (BFEE) at a constant applied potential of 1.38 V (versus SCE), have been investigated by excitation with a 633-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film was increasing during film growth. This finding was also confirmed by electrochemical examination. Moreover, the Raman bands assigned to radical cations and dications in doped PMeT films were found approximately at 1420 and 1400 cm(-1), respectively. Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrations increase with the increase of doping level. Successive cyclic voltammetry was proved to be an effective approach to improving the doping level of as-grown thin compact PMeT film.

Production of Poly(3-Hydroxybutyrate)by Fed-Batch Culture of Alcaligenes Eutrophus at Phosphorus Limitation in 50 L fermenter

Poly(3-hydroxybutyrate) (PHB) is an intracellular carbon and energy storage material accumulated by many kinds of microorganism under unfavorable growth conditions. For the production of PHB, Alcaligenes eutrophus has been widely used because it is easy to grow, and its physiological and biochemical changes during the PHB synthesis is understood in details. A very high concentration and productivity of PHB could be obtained by fed-batch culture of Alcaligenes eutrophus with phosphate limitation in 50 L fermenter.

SYNTHESIS OF SOLUBLE POLY(3-HEXYL-2,5-THIENYLENE VINYLENE) FROM THIOPHENE

Soluble poly(3-hexyl-2,5-thienylene vinylene) (PHTV) was readily synthesized from thiophene in a yield better than that of the precursor method to prepare poly(thienylene vinylene) (PTV). The bandgap of the polymer is about 1.8 eV, which is comparable with that of PTV. Owing to the introduction of alkyl side groups onto the backbone of the polymer, it can be dissolved in common organic solvents such as chloroform, THF and toluene. The synthesis of soluble PHTV is a very important approach to preventing oxidation and to improving the properties and the processbility of the PTV. The existence of alkyl side groups in PHTV does not affect its, bandgap and thermal properties as compared with PTV. After doping with FeCl3, the conductivity of PHTV is as high as 1.1 x 10(-2) S/cm. The soluble PHTV can be easily transformed into thin film with much better quality than that of the PTV film prepared by the traditional precursor method, which is very important for fabricating devices with good properties.

SYNTHESIS OF NOVEL BLOCK COPOLYMERS OF POLY(3-HYDROXYBUTYRIC ACID)WITH POLY(ETHYLENE GLYCOL)THROUGH ANIONIC POLYMERISATION

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.

The Crystallization of Poly (3-dodecyltbiophene) in an Oriented Solidification Environment

The crystallization behaviors of poly (3-dodecylthiophene) (P3DDT) under two different oriented solidification conditions. i e..' two different relative relations (90° and 180°) between the directions of gravity and solidification. were investigated. X-ray diffraction results reveal that although similar layered structures are formed, under the condition of the relative relation 180°. temperature; gradient has greater effects on the perfect degree of the layered structures of P3DDT. It also can be concluded that after recrystallization. the layered structures of P3DDT can be improved at relative relation 90°, but the orderly degree of the arrangements of alkyl side chains are not improved yet, even is reduced for both of the oriented solidification conditions.

Crystallization Behevior of Poly(3-dodecylthiophene)

The crystallization behavior of poly (3-dodecylthiophene) (P3DDT) is studied bq differential scanning calorimetry (DSC) under different cooling rates. When the methods of Jeziorny., Ozawa and a new one proposed by our laboratory are applied to describe its nonisothermal crystallization behavior, the new one is confirmed to be the best and convenient. By determining kinetic parameters, the analysis of the nonisothermal crystallization behavior is performed. According to Kissinger method, the crystallization activation energy of P3DDT is also evaluated.

Solvent and Temperature Effects on Spectral Properties of Two Poly(3-alkyl)thiophene Derivatives

Two alkyl substituted polythiophene derivatives: poly(3-hexylthiophene)(P3HT) and poly(3-decylthiophene)(P3DT), have synthesized by oxidation coupling polymerization of 3-alkylthiophene using iron(III) chloride as catalyst in chloroform. While both polymers in pure chloroform solution have maximum absorption at approximately same wavelength of 440nm, they behave differently with respect to changes observed on their UV-visible and photoluminescence spectra when the quality of the poor solvent is changed in good solvent (chloroform) / poor solvent (methanol) mixtures. With increasing volume fraction of methanol in mixtures, the absorption spectra of P3HT and P3DT red-shift, peaking at maximum wavelength of 495nm (P3HT) and 510nm(P3DT). Furthermore, the absorption spectra of the two polymers in chloroform blue-shift as the temperature rises. P3HT shows 4.73nm blue-shifts at 50℃ in contrast to the case at 20℃, while P3DT blue-shifts about 5.04nm. The photoluminescence spectra of the two polymers in mixed solution are also investigated, which show that the luminescence spectra shift to longer wavelength with an accompanying drop in the PL intensity as methanol is increased. The absorption and emission spectra of the two polymers in a poor solvent and a thin film are similar, which indicate that a similar longer conjugation length in the two cases. It could conclude that the polymers exist almost the same conformations and aggregations in both a poor solvent and a thin film. P3DT exhibits more sensitive spectra properties (big red-shifts in both absorption and luminescence spectra in poor solvents and large blue-shifts at high temperature) with contrast to P3HT, which imply that long side alkyl may improve the chromic properties of the polymer.

Agro-Industrial Waste Materials as Substrates for the Production of Poly(3-Hydroxybutyric Acid)

Accumulation of recalcitrant plastics in the environment has become a world-wide problem in today’s societies. Rapid depletion of natural resources for synthetic plastics along with environmental concerns has directed research towards finding alternatives to petroleum-based polymers. Poly(3-hydroxybutyric acid) P(3HB), as one of these alternatives, have attracted much attention in recent years due to their varied mechanical properties, biocompatibility and biodegradability. The aim of this study was to identify an agro-industrial waste resource economically suitable for large-scale production of P(3HB), to optimize the production using Response Surface Methodology in small-scale and subsequently, to test the production in a continuously stirred tank reactor. Among a range of agro-industrial waste, orange peel was selected as the most suitable for P(3HB) production. P(3HB) concentration of 1.24 g P(3HB)/L culture broth with 41% P(3HB)/dcw yield was obtained using orange peel as the sole carbon source in optimized medium with a modified strain of Bacillus subtilis (B. subtilis OK2).

Preparation and Characterization of Clay (Maghnite-H)/Poly(3,4-Ethylenedioxythiophene) Composites

Composites of Maghnite-H, a Montmorillonite sheet silicate clay, exchanged with protons, and Poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared by in situ chemical polymerization of the 3,4-ethylenedioxythiophene, without the use of solvent or oxidant. The effect of changing monomer/clay ratio was studied and the resultant composite structures were characterized by Inferred spectroscopy, 27Al and 13CSolid-State NMR spectroscopy, scanning electron microscopy and powder X-ray diffraction. All analyses are consistent with a structure were the polymer is (partially) intercalated into the clay structure, which in favourable cases lead to exfoliation. The presence of the clay in the polymer leads to a desired increase in thermal stability as witnessed by thermogravimetry.

Effects of Side-Chain on Conformational Characteristics of Poly(3,5-Dimethyl-Phenyl Acrylate) in Toluene at 40℃

The intrinsic viscosity [η] of poly(3,5-dimethylphenylacrylate) (35PDMPA)solutions were evaluated throughout the measurements of the flow times of toluene and polymer solutions by classical Huggins, and Kraemer’s methods using a Cannon-Ubbelohde semi-micro-dilution capillary viscometer in a Cannon thermostated water bath at 40℃ ± 0.02℃. The values of Huggins’ constant estimated ranged from 0.2 to 0.4 which were within expectations. The intrinsic viscosities and molecular weight relationship was established with the two-parameter classical models of Staudinger-Mark-Houwink-Sakurada and Stockmayer-Fixman. Conformational parameter C∞ and σ indicated 35PDMPA be semi flexible. Also, the rigidity of 35PDMPA was confirmed by Yamakawa-Fuji wormlike theory modified by Bohdanecky. The molecular parameters were estimated and compared. The results showed that 35PDMPA behaves like a semi-rigid polymer in toluene at 40℃ rather than a random coil flexible macromolecule.

STUDY ON BIODEGRADABILITY OF POLY (3-HYDROXYBUTYRATE-co-3-HYDROXYVALERATE)/ORGANOPHILIC MONTMORILLONITE NANOCOMPOSITES

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading method in soil suspension. The relationship between structure and biodegradability of PHBV/OMMT nanocomposites was investigated. The results showed that the biodegradability of PHBV/OMMT nanocomposites decreased with increasing amount of OMMT and it was related to the number of PHBV degrading microorganisms in degradation environment, the anti-microbial property of OMMT and the degree of crystallinity of the nanocomposites.

Preparation of Poly(3-hydroxybutyrate) Porous Films by Microemulsion Templates Method

Porous poly(3 hydroxybutyrate)(PHB) membranes were prepared by microemulsion templates. The influence of microemulsion templates on pore size and porosity of the PHB membranes were studied. Preliminary studies showed that the pore size made by microemulsion templates were smaller and were estimated in the range of 100~500 nanometer. In this research, the ultraviolet/visible light spectrometer was applied in the investigation of H 2O/Span85 Tween60/chloroform reserve microemulsion. Surfactant content(P) and water content(R) were optimized. Furthermore, the effects of variation of P and R on the pore size and porosity of PHB films were discussed.

The Effects of Accelerated Photooxidation on Molecular Weight and Thermal and Mechanical Properties of PHBV/Cloisite 30B Bionanocomposites

The effects of accelerated photooxidation on the molecular weight and thermal and mechanical properties of Cast PHBV and PHBV/Cloisite 30B(3 wt%)bionanocomposites are investigated herein.Through size exclusion chromatography(SEC)analysis,a significant decrease in both weight and number average molecular weights was observed for all irradiated samples over time,resulting from the chain scission mechanism.Differential scanning calorimetry(DSC)data indicated a decrease in degree of crystallinity and melting temperature after UV exposure,with the appearance of double melting peaks related to the changes in the crystal structure of PHBV.Thermal stability,tensile and thermo-mechanical properties were also reduced consecutively in photooxidation,being more pronounced for Cast PHBV.This study shows that the incorporation of Cloisite 30B in PHBV provides a better resistance to photooxidation in comparison with the neat polymer.

Improved nitrogen reduction electroactivity by unique MoS_(2)‐SnS_(2) heterogeneous nanoplates supported on poly(zwitterionic liquids)functionalized polypyrrole/graphene oxide

Unique MoS_(2)‐SnS_(2)heterogeneous nanoplates have successfully in‐situ grown on poly(3‐(1‐vinylimidazolium‐3‐yl)propane‐1‐sulfonate)functionalized polypyrrole/graphene oxide(PVIPS/PPy/GO).PVIPS can attract heptamolybdate ion(Mo7O246−)and Sn^(4+)as the precursors by the ion‐exchange,resulting in the simultaneous growth of 1T’‐MoS2 and the berndtite‐2T‐type hexagonal SnS_(2)by the interfacial induced effect of PVIPS.The obtained MoS_(2)‐SnS_(2)/PVIPS/PPy/GO can serve as electrocatalysts,exhibiting good NRR performance by the synergistic effect.The semi‐conducting SnS_(2)would limit the surface electron accessibility for suppressing HER process of 1T’‐MoS_(2),while metallic 1T’‐MoS_(2)might efficiently improve the NRR electroactivity of SnS_(2)by the creation of Mo‐Sn‐Sn trimer catalytic sites.Otherwise,the irreversible crystal phase transition has taken place during the NRR process.Partial 1T’‐MoS_(2)and SnS_(2)have electrochemically reacted with N_(2),and irreversibly converted into Mo^(2)N and SnxNz due to the formation of Mo−N and Sn−N bonding,meanwhile,partial SnS_(2) has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system.It would put forward a new design idea for optimizing the preparation method and electrocatalytic activity of transition metal dichalcogenides.