Cinnamoyl Pluronic F127 as a Stimuli-Sensitive Amphiphile

Cinnamoyl Pluronic F127 (CP F127) was prepared by reacting cinnamoyl chloride and Pluronic F127. On the ¹H NMR spectrum of CP F127, 1.2 moiety of cinnamoyl group was found to be attached to one molecule of CP F127. Using pyrene as a fluorescence probe, it was found that not only Pluronic F127 but also CP F127 could be readily assembled into micelles, and the critical micelle concentration was around 0.015 mg/ml and 0.03 mg/ml, respectively. Pluronic F127 in aqueous solution (2% w/v) could form no particles in 10–20°C, but particles (ca. 30 nm in diameter) were detected on a dynamic light scattering machine in 25–40°C possibly due to the thermal micellization. However, CP F127 was assembled into particles (ca. 230 nm) even in the lower temperature range, possibly because of the intermolecular hydrophobic interaction of the cinnamoyl group. The particle size of CP F127 strongly depended on the medium temperature and UV irradiation time. CP F127 was a good emulsifier for the preparation of O/W emulsions. The oil droplet size markedly increased upon UV irradiation (254 nm, 6 W), possibly because of the photo-dimerization of cinnamoyl group, but it was little affected by the temperature change (10–40°C).     

Microstructure transition of hydrophilic modified ibuprofen and Pluronic copolymer F127 complexes

The effect of the aggregation state of Pluronic copolymer (PEO₁₀₀–PPO₆₅–PEO₁₀₀, F127) and the concentration of hydrophilic modified ibuprofen (Ibuprofen–PEG800, IP800) on the interaction between F127 and IP800 was systematically investigated by nuclear magnetic resonance, dynamic light scatter (DLS), surface tension, and freeze-fractured transmission electron microscopy. In the solution of F127 unimers (5 °C), F127 unimers tended to wrap around IP800 micelles, and the binding model of F127 unimers to IP800 micelles transferred from wrapping around to partly threading through with increasing IP800 concentration. The latter binding model was straightly confirmed by nuclear Overhauser enhancement spectroscopy. As the aggregation state of F127 is in the beginning of the micellization (20 °C), the addition of IP800 significantly promoted the micellization of F127 to form the F127/IP800 complex with F127 micelles as the skeleton called the F127–micelle complex. The sudden decrease of the size obtained from DLS stemmed from the disruption of the F127–micelle complex and accompanying rehydration of PPO which is weaker compared with refs. The amount of IP800 to disintegrate the F127–micelle complex increased in the F127–micelle-dominated solution (40 °C) compared to that at 20 °C.     

Diffusion Coefficients and Structure Properties in the Pluronic F127/n‐C4H9OH/H2O System

Abstract

Diffusion coefficients of different aggregates in aqueous solutions formed by an amphiphilic block copolymer, Pluronic F127 (F127), were determined by cyclic voltammetry, and the critical micelle concentration (CMC, 4.31 × 10^?4 mol L^?1) of F127 was obtained. The added n‐butanol facilitates the formation of micelles from the monomers of F127 and makes the critical micelle temperature (CMT) of F127 solutions decrease. The diffusion coefficient of the F127 micelles decreases relatively fast at first with increasing n‐butanol and then the decreasing trend slows after the solubilization of n‐butanol in micelles reaches maximum.     

Hollow fiber-based liquid-phase microextraction (HF-LPME) of isradipine and its main metabolite followed by chiral HPLC analysis: application to an in vitro biotransformation study

An enantioselective liquid chromatographic method using two-phase hollow fiber liquid-phase microextraction (HF-LPME-HPLC) was developed for the determination of isradipine (ISR) enantiomers and its main metabolite (pyridine derivative of isradipine, PDI) in microsomal fractions isolated from rat liver. The analytes were extracted from 1 mL of microsomal medium using a two-phase HF-LPME procedure with hexyl acetate as the acceptor phase, 30 min of extraction, and sample agitation at 1,500 rpm. For the first time, ISR enantiomers and PDI were resolved. For this separation, a Chiralpak® AD column with hexane/2-propanol/ethanol (94:04:02, v/v/v) as the mobile phase at a flow rate of 1.5 mL min^?1 was used. The column was kept at 23?±?2 °C. The drug and metabolite detection was performed at 325 nm and the internal standard oxybutynin was detected at 225 nm. The recoveries were 23% for PDI and 19% for each ISR enantiomer. The method presented quantification limits (LOQ) of 50 ng mL^?1 and was linear over the concentration range of 50–5,000 and 50–2,500 ng mL^?1 for PDI and each ISR enantiomer, respectively. The validated method was employed to an in vitro biotransformation study of ISR using rat liver microsomal fraction showing that (+)-(S)-ISR is preferentially biotransformed.     

Thermally reversible pluronic/heparin nanocapsules exhibiting 1000-fold volume transition

Novel Pluronic/heparin composite nanocapsules that exhibit a thermally responsible swelling and deswelling behavior were synthesized. Pluronic F-127 preactivated with p-nitrophenyl chloroformate at its two terminal hydroxyl groups was dissolved in a methylene chloride phase. The organic phase was dispersed in an aqueous phase containing heparin. At an organic/aqueous interface, Pluronic-cross-linked heparin nanocapsules were produced. They exhibited a 1000-fold volume transition (ca. 336 nm at 25 degrees C; ca. 32 nm at 37 degrees C), and a reversible swelling and deswelling behavior when the temperature was cycled between 20 and 37 degrees C. The reversible volume transition of Pluronic nanocapsules was caused by micellization and demicellization of cross-linked Pluronic polymer chains within the nanocapsule structure in response to temperature. The morphological characters were investigated with transmission electron microscopy and small angle neutron scattering. Pluronic/heparin nanocapsules had an aqueous fluid-filled hollow interior with a surrounding shell layer below the critical temperature, but they became a collapsed core/shell structure similar to that of Pluronic micelles above it.     

The influence of pH on the stability constants of lanthanum and europium complexes with humic acids

Complex formation of humic acids (HA)_n with La³⁺ and Eu³⁺ was studied. Commercial (HA)_n was purified and characterized. The stability constants were determined at several pH values and 0.2?M NaClO₄ ionic strength by the Shubert??s method of radiochemical ionic exchange. The slopes of the lines $ \log ((\lambda_{0} /\lambda ) - 1) = \log \beta_{\text{M,j(HA)n}}^{\exp } + {\text{j}} * \log \left[ { ( {\text{HA)}}_{\text{n}} } \right] $ were dependent on the [(HA)_n]. The values of log $ \beta_{\text{M,j(HA)n}}^{\exp } $ for j?=?1 were the following: 6.29?±?0.04 (pH 4.9?±?0.4) and 7.61?±?0.03 (pH 5.9?±?0.1) for lanthanum and 7.31?±?0.01 (pH 5.9?±?0.2) for europium. Log $ \beta_{\text{M,j(HA)n}}^{\exp } $ was determined as well for higher values of the j parameter and these values were: 12.2?±?0.1 (j?=?2, pH 7.7?±?0.2), 15.6?±?0.2 (j?=?3, pH 4.9?±?0.4) and 16.05?±?0.07 (j?=?3, pH 5.9?±?0.1), for lanthanum and 13.18?±?0.03 (j?=?2, pH 5.9?±?0.1) for europium. A discussion is presented about the complex formation regarding pH and [(HA)_n].     

Hierarchical mesoporous carbon materials: preparation by direct tri-constituent co-assembly and the electrochemical performance

Hierarchical mesoporous carbon materials with large microporosity were prepared by direct tri-constituent co-assembly with the use of resols as the carbon precursor, tetraethyl orthosilicate as the inorganic precursor, and triblock copolymer F127 as the soft template. Bimodal pore size distributions in the range of 1.5–4 and 7.5–12 nm were obtained in the synthesized hierarchical mesoporous carbon materials after etching of silica by HF acid, showing a high surface area of 1,675 m²?g^?1 with a large pore volume of 2.06 cm³?g^?1. The electrochemical performance of the hierarchical mesoporous carbons was evaluated as an electrode material for electrochemical supercapacitor, showing a specific capacitance as high as 152 F?g^?1 at a scan rate of 5 mV?s^?1 in 6 M KOH aqueous solution and a good cycling stability with capacitance retention of 99 % over 500 cycles.     

Regulation of vincamine biosynthesis and associated growth promoting effects through abiotic elicitation,cyclooxygenase inhibition,and precursor feeding of bioreactor grown Vinca minor hairy roots

Hydroxylase/acetyltransferase elicitors and cyclooxygenase inhibitor along with various precursors from primary shikimate and secoiridoid pools have been fortified to vincamine less hairy root clone of Vinca minor to determine the regulatory factors associated with vincamine biosynthesis. Growth kinetic studies revealed that acetyltransferase elicitor acetic anhydride and terpenoid precursor loganin significantly reduce the growth either supplemented alone or in combination (GI?=?140.6?±?18.5 to 246.7?±?24.3), while shikimate and tryptophan trigger biomass accumulation (GI?=?440.2?±?31.5 to 540.5?±?40.3). Loganin also downregulates total alkaloid biosynthesis. Maximum flux towards vincamine production (0.017?±?0.001 % dry wt.) was obtained when 20-day-old hairy roots were fortified with secologanin (10 mg/l) along with tryptophan (100 mg/l), naproxen (8.4 mg/l), hydrogen peroxide (20 μg/l), and acetic anhydride (32.4 mg/l). This was supported by RT PCR (qPCR) analysis where 2- and 3-fold increase in tryptophan decarboxylase (TDC; RQ?=?2.0?±?0.09) and strictosidine synthase (STR; RQ?=?3.3?±?0.36) activity, respectively, was recorded. The analysis of variance (ANOVA) for growth kinetics, total alkaloid content, and gene expression studies favored highly significant data (P?<?0.05–0.01). Above treated hairy roots were also up-scaled in a 5-l stirred-tank bioreactor where a 40-day cycle yielded 8-fold increase in fresh root mass.     

Molecular and Kinetic Characterization of Two Extracellular Xylanases Isolated from Leucoagaricus gongylophorus

In this work, the xylanolytic profile of Leucoagaricus gongylophorus was studied, and two extracellular enzymes with xylanolytic activity (XyLg1 and XyLg2) were isolated, purified, and characterized. XyLg1 has a molecular mass of about 38 kDa and pI greater than 4.8. For beechwood xylan substrate, XyLg1 showed an optimum temperature of 40 °C, optimum pH between 8.5 and 10.5, and Km?=?14.7?±?7.6 mg mL^?1. Kinetic studies of the XyLg1 using polygalacturonic acid as substrate were developed, and the enzyme showed optimum pH 5.5, optimum temperature between 50 and 60 °C, and Km?=?2.2?±?0.5 mg mL^?1. XyLg2 has molecular weight of about 24 kDa and pI less than 4.8, and thus is an acid protein. Parameters such as optimum temperature (70 °C) and pH (4.0), as well as the kinetic parameters (Km?=?7.4?±?2.0 mg mL^?1) using beechwood xylan as substrate, were determined for XyLg2. This enzyme has no activity for polygalacturonic acid as substrate. XyLg1 and XyLg2 are the first native xylanases isolated and characterized from L. gongylophorus fungi and, due to their biochemistry and kinetic features, they have potential to be used in biotechnological processes.     

Tuning of the Temperature Window for Unit‐Cell and Pore‐Size Enlargement in Face‐Centered‐Cubic Large‐Mesopore Silicas Templated by Swollen Block Copolymer Micelles

The unit‐cell size and pore diameter as functions of temperature are investigated in the syntheses of FDU‐12 silicas with face‐centered cubic structure templated by Pluronic (PEO‐PPO‐PEO) block copolymer micelles swollen by toluene. The temperature range in which the unit‐cell size and pore size strongly increase as temperature decreases is correlated with the critical micelle temperature (CMT) of the surfactant. While Pluronic F127 affords a wide range of unit‐cell parameters (28–51 nm) and pore diameters (16–32 nm), it renders moderately enlarged pore sizes at 25 °C. The use of Pluronic F108 with higher CMT affords FDU‐12 with very large unit‐cell size (～49 nm) and large pore diameter (27 nm) at 23 °C. Large unit‐cell size (40–41 nm) and pore size (22 nm) were obtained even at 25 °C. The application of Pluronics F87 and F88 with much smaller molecular weights and higher CMTs also allows one to synthesize FDU‐12 with quite large unit‐cell parameters and pore sizes at room temperature. The present work demonstrates that one can judiciously select Pluronic surfactants with appropriate CMT to shift the temperature range in which the pore diameter is readily tunable.     

Adsorption properties of phenolic resin-based mesoporous carbons obtained by using mixed templates of Pluronic F127 and Brij 58 or Brij 78 polymers

Phenolic resin-based mesoporous carbons were synthesized by using mixed templates of Pluronic F127 and Brij 58 or Brij 78. For the purpose of comparison three samples of nanoporous carbons were prepared by using single templates of Pluronic F127, Brij 58 and Brij 78 polymers, respectively. Adsorption properties of the aforementioned carbons were studied by nitrogen adsorption at ?196?°C. The resulting carbons featured high specific surface areas ranging from 641 m²/g for the sample obtained in the presence of Brij 58 polymer to 825 m²/g for the carbon prepared by using a mixed template containing 23% of Pluronic F127 and 77% of Brij 58 and from 588 m²/g for the sample obtained in the presence of Brij 78 polymer to 813 m²/g for the carbon prepared by using Pluronic F127 only. It was shown that the width of mesopores increases with increasing amount of Brij 58 or Brij 78 in the mixture of one of these polymers with Pluronic F127, suggesting that Brij polymers act also as micelle expanders.     

Thermoresponsive Star-Shaped Poly(2-isopropyl-2-oxazoline) in Aqueous Solution

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazoline) with t-butylcalix[8]arene core was studied by light scattering methods in aqueous solution. The sample under investigation has M_w = 19600 g mol^?1 and PDI of arms 1.41. The bimodal distribution of scattering objects was observed even at room temperature. The redistribution of these two kinds of particles takes place at T = 27°–36°C. At higher temperatures the growth of large particles, disappearance of the small component, and appearance-disappearance of “middle-size” aggregates were observed. Only the large particles with the hydrodynamic radius 95 nm exist in proximity to LCST (37.5°C).     

Development of disulfide core-crosslinked pluronic nanoparticles as an effective anticancer-drug-delivery system

Thiolated Pluronic (Plu‐SH) nanoparticles are developed as potential articulate, target‐specific anticancer‐drug carriers for intracellular drug release triggered by the difference in redox potential in tumor cells. The cores of the micelles are formed by the disulfide bonds of the functionalized Pluronic F127, when dissolved in an aqueous solution. The nanoparticles are 95.6 ± 18.6 nm in size, and 235.6 ± 63.7 nm after encapsulation of the hydrophobic drug molecules. The drug‐loaded micelles show effective stability in blood‐plasma conditions and the kinetics of micelle stability and drug release are shown. Paclitaxel‐loaded micelles display approximately 39% cell viability in A549 cells.

     

Highly Thermostable and pH-Stable Cellulases from Aspergillus niger NS-2: Properties and Application for Cellulose Hydrolysis

Optimization of cultural conditions for enhanced cellulase production by Aspergillus niger NS-2 were studied under solid-state fermentation. Significant increase in yields (CMCase 463.9?±?20.1 U/g, FPase 101.1?±?3.5 U/g and β-glucosidase 99?±?4.0 U/g) were obtained under optimized conditions. Effect of different nutritional parameters was studied to induce the maximum production of cellulase complex. Scale-up studies for enzyme production process were carried out. Characterization studies showed that enzymes produced by A. niger NS-2 were highly temperature- and pH stable. At 50 °C, the half life for CMCase, FPase, β-glucosidase were approximately 240 h. Cellulases from A. niger NS-2 were stable at 35 °C for 24 h over a broader pH range of 3.0–9.0. We examined the feasibility of using steam pretreatment to increase the saccharification yields from various lignocellulosic residues for sugar release which can potentially be used in bioethanol production. Saccharification of pretreated dry potato peels, carrot peels, composite waste mixture, orange peels, onion peels, banana peels, pineapple peels by crude enzyme extract from A. niger NS-2, resulted in very high cellulose conversion efficiencies of 92–98 %.     

Biomimetic approach towards the preparation of hydroxyapatite and hydroxyapatite/chitosan/β-cyclodextrin nanoparticles: application to controlled drug release

Hydroxyapatite (HAp) and hydroxyapatite/chitosan/β-cyclodextrin (HAp/CS/β-CD) nanoparticles were successfully prepared in the modified simulated body fluid (SBF) solution at the physiological conditions (pH 7.4, temperature?=?37 °C). CS/β-CD nanoparticles acted as templates for the synthesis of HAp/CS/β-CD nanoparticles to improve the nanoarchitecture of HAp and its crystallinity.The nanoparticles were characterized by FT-IR spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Kneading and coprecipitation methods were applied to prepare the inclusion complex involving β-CD and p-THPP (5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin), a photosensitizer for anti-cancer drugs. The 1:1 stoichiometric ratio of the formed inclusion complex was characterized by a formation constant of 7.216?×?10² mol^?1 dm³ and analyzed by ¹H NMR, FTIR, and UV–Vis. The p-THPP delivery release in vitro was in this order: HAp/CS/β-CD?<?CS/β-CD?<?<?HAp/β-CD?<?β-CD, hinting at a better controlled release by HAp/CS/β-CD nanoparticles.     

Biocompatible APTES–PEG Modified Magnetite Nanoparticles: Effective Carriers of Antineoplastic Agents to Ovarian Cancer

Magnetite nanoparticles are particularly attractive for drug delivery applications because of their size-dependent superparamagnetism, low toxicity, and biocompatibility with cells and tissues. Surface modification of iron oxide nanoparticles with biocompatible polymers is potentially beneficial to prepare biodegradable nanocomposite-based drug delivery agents for in vivo and in vitro applications. In the present study, the bare (10 nm) and polyethylene glycol (PEG)–(3-aminopropyl)triethoxysilane (APTES) (PA) modified (17 nm) superparamagnetic iron oxide nanoparticles (SPIO NPs) were synthesized by coprecipitation method. The anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), were separately encapsulated into the synthesized polymeric nanocomposites for localized targeting of human ovarian cancer in vitro. Surface morphology analysis by scanning electron microscopy showed a slight increase in particle size (27?±?0.7 and 30?±?0.45 nm) with drug loading capacities of 70 and 61.5 % and release capabilities of 90 and 93 % for the DOX- and PTX-AP-SPIO NPs, respectively (p?<?0.001). Ten milligrams/milliliter DOX- and PTX-loaded AP-SPIO NPs caused a significant amount of cytotoxicity and downregulation of antiapoptotic proteins, as compared with same amounts of free drugs (p?<?0.001). In vivo antiproliferative effect of present formulation on immunodeficient female Balb/c mice showed ovarian tumor shrinkage from 2,920 to 143 mm³ after 40 days. The present formulation of APTES–PEG-SPIO-based nanocomposite system of targeted drug delivery proved to be effective enough in order to treat deadly solid tumor of ovarian cancer in vitro and in vivo.     

Determination of phosphate in freshwater samples by flow-injection with lucigenin chemiluminescence

Lucigenin chemiluminescence (CL) in conjunction with flow-injection analysis (FIA) is used for the determination of phosphate in freshwater samples. The procedure is based on the formation of molybdophosphoric heteropoly acid (MoP–HPA) by the reaction of phosphate and ammonium molybdate under acidic conditions. CL emission was observed as a result of oxidation of lucigenin in aqueous sodium hydroxide solution in the presence of MoP–HPA. Calibration was linear up to 500?µg?L^?1 (r ^2?=?0.9998; n?=?8), with a detection limit (S/N?=?3) of 0.95?µg?L^?1. An injection throughput of 120 h^?1, and relative standard deviation (RSD; n?=?4) of 1.3–3.2% were achieved in the concentration range studied. An on-line chelating column was used to remove interfering cations. The method was applied to freshwater samples, and the results (51?±?1.0 – 107?±?2.0?µg?L^?1) did not differ significantly from results obtained using a spectrophotometric method (52.5?±?1.0 – 102?±?2.0?µg?L^?1) at 95% confidence level (t-test).     

The Effects of Caffeine Ingestion Before Passive Heat Loading on Serum Leptin Levels in Humans

We assessed the effects of ingesting caffeine before passive heat loading (PHL) on serum leptin and sweating response, which are both physiological responses associated with energy expenditure. The subjects were nine male university students (age, 24.1?±?3.5 years; height, 173.4?±?7.6 cm; weight, 69.2?±?5.7 kg; maximal oxygen consumption, 48.6?±?4.7 ml???kg^?1???min^?1). This study used a within-subject, random, crossover design. Tests were performed twice at the same time (2–5 p.m.) at a 1-week interval following 3 mg?kg^?1 caffeine ingestion (Caff-I) or not (No-Caff). PHL included a half bath in hot water (42?±?0.5 °C for 30 min) in a thermoneutral climate chamber (25?±?0.5 °C, 60?±?3 % relative humidity, <1 m/s air velocity). After PHL, blood levels of leptin and free fatty acids were significantly higher in the Caff-I compared to those in the No-Caff after PHL (P?<?0.01). Waist circumference and whole-body sweat loss volume were significantly higher in the Caff-I compared to those in the No-Caff (P?<?0.001). Mean active sweat gland density was significantly higher in the Caff-I compared to those in the No-Caff at 10 min during PHL (P?<?0.001). The results suggest that ingesting caffeine before PHL is more energy efficient than that of a single PHL.     

Soft template synthesis of donor–acceptor conjugated polymer nanoparticles: Structural effects,stability, and photothermal studies

Donor–acceptor conjugated polymer nanoparticles and nanofibers, based on Poly[4,4‐bis(2‐ethylhexyl)‐cyclopenta[2,1‐b;3,4‐b']dithiophene‐2,6‐diyl‐alt?2,1,3‐benzoselenadiazole‐4,7‐diyl] (PCPDTBSe), were synthesized using Pluronic F127 as a template. The nanomaterials were compared to previously reported PCPDTBSe nanoparticles, which were synthesized without the use of a template. Our goal was to improve on the aqueous stability and photothermal heating efficiency of the previously synthesized PCPDTBSe nanoparticles by decreasing their size and coating them with a biocompatible surfactant. The pluronic wrapped PCPDTBSe (PW‐PCPDTBSe) nanoparticles (40–60 nm) showed excellent aqueous stability compared to the PW‐PCPDTBSe nanofibers (d = 20–60 nm, l = 200–1000 nm) and previously synthesized PCPDTBSe nanoparticles (150 nm). Under stimulation from 800 nm near infrared light (3 W, 1 min), the PW‐PCPDTBSe nanoparticles showed greater heat generation (ΔT = 47 °C) compared to bare PCPDTBSe nanoparticles and PW‐PCPDTBSe nanofibers (ΔT = 35 °C for both). Cytotoxicity studies determined that both the PW‐PCPDTBSe nanoparticles and PW‐PCPDTBSe nanofibers displayed no significant toxicity toward either noncancerous small intestinal cells (FHs 74 Int) or colorectal cancer cells (CT26). Photothermal ablation studies confirmed that both the PW‐PCPDTBSe nanoparticles and the PW‐PCPDTBSe nanofibers can be used as localized photothermal agents to eradicate colorectal cancer cells due to their excellent ablation efficiency (>95% cell death at 15 µg/mL concentration). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1622–1632     

A viscosity-tunable polymer for DNA separation by microchip electrophoresis

A thermo-responsive separation matrix, consisting of Pluronic F127 tri-block copolymers of poly(ethylene oxide) and poly(propylene oxide), was used to separate DNA fragments by microchip electrophoresis. At low temperature, the polymer matrix was low in viscosity and allowed rapid loading into a microchannel under low pressure. With increasing temperatures above 25°C, the Pluronic F127 solution forms a liquid crystalline phase consisting of spherical micelles with diameters of 17–19 nm. The solution can be used to separate DNA fragments from 100 bp to 1500 bp on poly(methyl methacrylate) (PMMA) chips. This temperature-sensitive and viscosity-tunable polymer provided excellent resolution over a wide range of DNA sizes. Separation is based on a different mechanism compared with conventional matrices such as methylcellulose. To illustrate the separation mechanism of DNA in a Pluronic F127 solution, DNA molecular imaging was performed by fluorescence microscopy with F127 polymer as the separation matrix in microchip electrophoresis. Figure Temperature dependence of the viscosity of 20% w/w Pluronic F127 solution in 1xTBE buffer. Dotted approximates resultant curve.