Amount Of High Polymer Research Articles

Pluronics-Based Drug Delivery Systems for Flavonoids Anticancer Treatment.

This research concerns the investigation of the preparation of polymeric nanocarriers containing a flavonoid-naringenin, xanthohumol or isoxanthohumol-based on Pluronics by the thin-film formation method. The size of the formed micelles and their stability upon dilution were evaluated using Dynamic light scattering (DLS) analysis; the high values of the drug loading and the encapsulation efficiency confirmed that the proposed systems of flavonoids delivery consisting of Pluronic P123 and F127 nanomicelles could effectively distribute the drug into tumour tissues, which makes these nanocarriers ideal candidates for passive targeting of cancer cells by the enhanced permeation and retention (EPR) effect. The in vitro cytotoxicity of proposed flavonoids in the Pluronic formulations was investigated by the SRB assay with human colon cancer cells. We designed mixed polymeric micelles, which was a successful drug delivery system for the case of naringenin not being able to enhance the bioavailability and cytotoxic activity of xanthohumol and isoxanthohumol. Furthermore, it was observed that the higher amount of polymer in the formulation achieved better cytotoxic activity.

Effects of the carbon nanotube and polymer amounts on ultrafiltration membranes

Composite membranes with nano-sized inorganic materials have high selectivity, high hydrophilicity, and improved fouling resistance. Blending Carbon Nanotubes (CNTs) in the polymer solution improves membrane properties like hydrophilicity, water permeability, selectivity, and fouling resistance. The effect of the polymer amount, together with the CNT amount in the polymer solution on membrane properties, was investigated in this work. There was more than 10% increase in the hydrophilicity of the membranes with 1% CNT addition, but it was not altered with the polymer amount. The porosity was increased almost 30% by 1% CNT addition in membranes prepared by 10% and 12% polymer concentration (P-10:C-0 and P-12:C-0), but only 16% increase in porosity occurred in membrane prepared by 15% polymer concentration (P-15:C-0). The flux of the P-15:C-0 membrane was increased four times by 1% CNT addition. Besides, fouling resistance of the membranes decreased with increasing polymer amount but increased with increasing CNT amount. BSA rejection increased with increasing polymer amount or CNT amount in the polymer solution. Hence membranes prepared with a higher amount of polymer are more prone to membrane property improvements with CNT addition. The increase in flux and selectivity by CNT addition in all membranes prepared with different polymer concentrations will increase the membrane life-time and reduce the treatment cost.

Performance and drug deposition of kappa-carrageenan microspheres encapsulating ciprofloxacin HCl: Effect of polymer concentration.

It has been known that in respiratory disease, antibiotic is selected for respiratory diseases or lung infections and this research focused on ciprofloxacin HCl as a model. The aim was to evaluate the effect of kappa-carrageenan polymer concentrations on characteristics, release, and drug deposition in the lung. Ciprofloxacin HCl-carrageenan microspheres were produced with kappa carrageenan (0.75%, 0.50%, and 0.25%) as polymer and KCl (1.5%) as crosslinker. Physical characteristics were included morphology, size, moisture content, swelling index, mucoadhesivity, drug loading, entrapment efficiency, and yield. Freeze-dried microspheres were inhaled by animal, and drug deposition was observed. Results showed that dried, smooth, and spherical microspheres of size of 1.34 to 1.70 μm and loading of 15.63% to 38.72%. Entrapment efficiency and yield were 25.38%–51.61% and 52.53%–63.19%, respectively. Mucoadhesivity was 0.0059–0.0096 kg force, and release in 24 h was 74.38%–81.02%. Release kinetics demonstrated Higuchi mechanism. Increasing carrageenan concentration affected size, loading, and efficiency but did not influence adhesivity, yield, and release. Higher amount of polymer caused the lower deposit on the lungs. Respirable size of ciprofloxacin HCl-kappa carrageenan microspheres was successfully achieved target site and prolonged residence time in lungs.

Flocculation efficiency of reacetylated water soluble chitosan versus commercial chitosan

In this work, the flocculation efficiency of reacetylated chitosans were compared with those of commercially available chitosans. The flocculation properties were investigated in dispersion of clay by means of turbidity measurements, colloid titration and measurements of the floc size. Reacetylated chitosan dissolves in deionized water without any additives and exhibits good flocculation properties like a wider flocculation window but a higher amount of polymer. For commercial chitosan lower amounts of polymer were required for the flocculation of clay dispersion. Flocculation with commercial chitosan is possible even in basic range.

Intracellular polyhydroxyalkanoates recovery by cleaner halogen-free methods towards zero emission in the palm oil mill

Abstract In this study, the effect of extraction process, bacterial strain and cell PHA content on halogen-free recovery methods using sodium hydroxide (NaOH) and water as cleaner and more environmental friendly processes were examined for polyhydroxyalkanoates (PHA) recovery. The bacterial strains used were local isolate wild type Comamonas sp. EB172 and recombinant Cupriavidus necator ( C. necator ), with 30% and 50% of PHA content. It was found that the PHA was efficiently recovered from bacterial cells by the non-halogenated methods. Although the PHA purity obtained by water recovery method was lower than alkaline treatment, it does not have any adverse effect on the polymer molecular weight. The performance of the halogen-free methods depends on the microbial strain which is due to the difference in the thickness of the cell membranes. The intracellular PHA content also affected the effectiveness of the extraction methods for PHA recovery as higher amount of polymer in the cell increased the quantity of PHA recovered. The halogen-free methods using NaOH and water can serve as promising alternatives for conventional industrial halogenated solvent extraction process, since these new methods are environmentally more benign, effective and simple in operation. Finally, the potential of integrating PHA production and halogen free recovery system with the palm oil industry is discussed. It is expected that the proposed integrated system herein provides a more attractive proposition to utilize biomass as renewable resource for the production of value-added bioproducts like PHA, which will make the palm oil industry more sustainable and profitable, and promotes zero-emission at the mill.

Effect of Added Monosodium Glutamate on Characteristics of Polyamide Dope Solutions

Formic acid (FA) solutions prepared with various concentrations of polyamide 66 (PA 66) and monosodium glutamate (MSG) were evaluated in terms of properties, such as density, viscosity, and cloud point. The influence on density was insignificant, whereas the viscosity was strongly affected by the amount of PA 66 and MSG additive. The solutions were further evaluated by casting them in a flat film form and determining the demixing time in a humid atmosphere. The considered cases at lower polymer concentrations at various MSG amounts, indicated that the demixing time increased with increase in polymer concentration. The time for demixing, however, decreased for a given higher amount of polymer when the amount of additive was increased in the dope solution. Membranes were prepared at various coagulant bath temperatures. The tensile strength and degree of adsorption (DOA) of these membranes were found. The tensile strength was higher when the membranes were prepared at higher temperature. The DOA, on the other hand, was higher for the membranes formed at lower temperature.

Comparison of Chromatographic Performance for L-Phenylalanine-Derived Organic Phases on Silica by “Grafting from” and “Grafting to” Strategies

L-phenylalanine-derived polymerizable organogel, N’-octadecyl-Nα-(4-vinyl)-benzoyl-L-phenylalanineami- de (4) has been prepared according to the procedure described elsewhere. Compound 4 was successfully polymerized by surface initiated atom transfer radical polymerization (ATRP) from the initiator grafted silica particles (sil-poly4). It was also telomerized with 3-mercaptopropyltrimethoxysilane (MPS) and the telomer (T4) was grafted on to silica (sil-T4). TGA and elemental analysis measurement revealed that higher amount of polymer can graft by ATRP process than that of “grafting to” strategy. The results of 13C CP/MAS NMR measurement showed that the N-alkyl chain of the grafted polymers for both sil-poly4 and sil-T4 remained as less ordered gauche conformational form on silica surface and no inversion to trans form was occurred until temperature is increased up to 50?C. The retention of alkylbenzene samples showed that sil-poly4 prepared by “grafting from” method yielded extremely higher retention than conventional C18 phase however, sil-T4 prepared by conventional “grafting to” method showed lower retention than C18 phase. Aspects of molecular recognition were evaluated by the retention studies of a series of polycyclic aromatic hydrocarbons (PAHs) and aromatic positional isomers. We have observed sil-T4 yielded slightly higher selectivity for PAHs than sil-poly4 regardless the fact that it has low surface coverage and lower hydrophobic interactions. The enhanced selectivity observed for sil-T4 than C18 phases and sil-poly4 can be explained by the π - π interactions between the guest PAHs and carbonyl groups present in the polymer chain. In addition the aromatic moieties of compound 4 that aggregates through π - π interactions also contribute to the separation of PAHs for both sil-poly4 and sil-T4. The minimal π - π interactions between the carbonyl groups and guest molecules for sil-poly4 probably due to the presence of long chain initiator which restrict the polymer to form order thin layer over silica surface.

FTIR imaging of wheat endosperm cell walls in situ reveals compositional and architectural heterogeneity related to grain hardness.

Endosperm cell walls of cultivars of wheat (Triticum aestivum L.) selected for their endosperm texture (two soft and two hard) were analysed in situ by Fourier transform infrared (FTIR) microspectroscopy. FTIR imaging coupled with statistical analysis was used to map the compositional and structural heterogeneity within transverse sections from which cell contents had been removed by sonication. In the majority of grains analysed, two distinct populations of endosperm cells could be identified by spectral features that were related to cell morphology and age, regardless of cultivar. The main cell-wall component responsible for these differences was the polysaccharide arabinoxylan. In a few samples, this heterogeneity was absent, for reasons that are not understood, but this was not correlated to endosperm texture or growth conditions. Within the same population of endosperm cells, cell walls of hard endosperm could be distinguished from those of soft endosperm by their spectral features. Compared to hard cultivars, the peripheral endosperm of soft cultivars was characterised by a higher amount of polymer, whose spectral feature was similar to water-extractable arabinoxylan. In contrast, no specific compound has been identified in the central endosperm: structural differences within the polysaccharides probably contribute to the distinction between hard and soft cultivars. In developing grain, a clear difference in the composition of the endosperm cell walls of hard and soft wheat cultivars was observed as early as 15 days after anthesis.

Intercalation of Al13-Polyethyleneoxide Complexes into Montmorillonite Clay

AbstractNovel promising modified clays adsorbents were synthesized by intercalating hydroxy-Al polymer associated with poly(ethyleneoxide) in the interlayer of montmorillonite. Two different PEOs of low molecular weight (600) and high molecular weight (100,000) were used. In both cases, the resulting materials are hydrolytically stable and display a slightly better crystallinity than the materials prepared in the absence of PEO. Thermal analysis and infrared spectroscopy indicate changes in the PEO molecular conformation after intercalation revealing interactions between the polycations and the organic molecules. The chain length of the polymer has a strong influence on the surface area of the pillared materials obtained after calcination at 500°C. The use of the high molecular weight polymer leads to products with a higher specific surface area (about 400 m2/g) whereas the lower molecular weight compound does not modify significantly the surface areas. This behavior can be explained by the different nature of the species intercalated in the interlayer. PEO(600) leads to isolated organometallic species whereas PEO(100,000) seems to lead to a network of complexed polycations linked by ethylene oxide units. In the case of the PEO(100,000), high amounts of polymer in the pillaring solution provoke a partial dissolution of the octahedral layer of the clay.

Monomer-lsomerization Polymerization of Some Branched Internal Olefins with a Ziegler-Natta Catalyst

Abstract New examples for the monomer-isomerization polymerizations of some branched internal olefins, 4-methyl-2-pentene and 4-phenyl-2-butene, are presented. When these olefins are polymerized with A1(C2 H5)3-TiCl3 ([TiCl3] = 120 mmole/liter, A1/Ti = 3.0) catalyst at 80°C, considerable amounts of high polymers [27.5%/60 hr ([η] = 0.68 d1/g) and 35.6%/100hr, respectively] were obtained. From the additional fact that the isomerization from these 2-olefins to the mixture of their positional isomers including 1-olefins was observed during the polymerization, it is assumed that the polymerizations from these 2-olefins are performed with the 1-olefins which isomerized from the starting 2-olefins.

Molecular Weight Distribution of Polyoxymethylene Obtained in Solid-State Polymerization of Trioxane Catalyzed by BF3·O(C2H5)2

Abstract To clarify the reaction mechanism of the solid-state polymerization of trioxane, the molecular weight distribution of polyoxymethylene is measured. High molecular weight polymer is precipitated around the stirrer in an early stage, then low polymer, while the p-chlorophenol solution of polyoxymethylene is violently rotated by a glass stirrer at about 60°C. To fractionate polymer, this phenomenon is applied for the polyoxymethylene produced in the solid-state polymerization catalyzed by BF3·O(C2H5)2 in n-hexane medium at 40 and 50°C. The polymer obtained at a low conversion contains a large amount of high polymer part, and the amount of high polymer decreases with increasing conversion. It is estimated that high polymer is produced only at the initial stage of the polymerization and that the decrease of molecular weight of polymer at a high conversion in the solid-state polymerization may be due to the formation of low polymer at a high conversion and also to the degradation of high polymer during...