Pluronic Concentration Research Articles

Fabrication of electrospun antioxidant nanofibers by rutin‐pluronic solid dispersions for enhanced solubility

ABSTRACTIn this study, solid dispersions (SDs) and electrospinning combined methods were used to increase the bioavailability and solubility of a water insoluble drug. Pullulan (PUL) nanofibers containing rutin‐Pluronic SDs (PUL&RU@PF) were fabricated by electrospinning. Rutin was efficiently loaded with Pluronic SDs using a facile mixing method and the prepared SDs indicated that 4% w/v Pluronic concentration provided the optimal drug loading efficiency. Scanning electron microscopy (SEM) verified that the morphology of the complex nanofibers had a uniformly smooth surface with a porous structure. The amorphous state of rutin was examined by XRD and DSC. Moreover, rutin in the electrospun PUL‐rutin‐Pluronic complex structure displayed a fast release profile and equivalent antioxidant ability compared to that of raw rutin. In conclusion, PUL&RU@PF may be a promising alternative for enhanced solubility and UV stability with remaining rutin's inherent antioxidant ability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44859.

A novel approach of developing micro crystalline cellulose reinforced cementitious composites with enhanced microstructure and mechanical performance

This paper reports a novel approach of preparing aqueous suspensions of microcrystalline cellulose (MCC) for fabrication of cementitious composites. MCC was dispersed homogeneously in water using Pluronic F-127 as a surfactant with the help of ultrasonication process and the aqueous suspensions were added to cement/sand mixture to prepare cementitious composites. A commonly used stabilizing agent for MCC, carboxy methyl cellulose (CMC) was also used for the comparison purpose. The prepared suspensions were characterized through visual inspection, UV-Vis spectroscopy and optical microscopy. The developed composites were characterized for their bulk density, flexural and compressive properties as well as microstructure. The influence of Pluronic and CMC concentration, superplasticizer, dispersion technique and dispersion temperature on mortar's mechanical performance was thoroughly studied to find out the optimum conditions. Overall, Pluronic (with Pluronic: MCC ratio of 1:5) led to better MCC dispersion as well as dispersion stability as compared to CMC. The best mechanical performance was achieved with Pluronic in combination with superplasticizer using ultrasonication process, resulting in improvement of 106%, 31% and 66% in flexural modulus, flexural strength and compressive strengths, respectively (highest values reported till date). The bulk density and hydration of cementitious composites also improved significantly with the addition of MCC.

Preparation and characterisation of novel polysulfone membranes modified with Pluronic F-127 for reducing microalgal fouling

In this study, hydrophilic and fouling-resistant polysulfone (PS) membranes were fabricated using the phase inversion method to reduce membrane fouling caused by microalgal culture. The Pluronic F-127 polymer, which is used as a hydrophilic co-polymer, was added to the membranes to improve the membrane properties. Characteristic specifications of the fabricated membranes, such as morphology, surface roughness, chemical structures and hydrophobicity/hydrophilicity, were studied using scanning electron microscopy, atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflection-fourier infrared (ATR-FTIR) spectroscopy and contact angle devices. According to the results obtained, it was observed that, with the increase of the Pluronic F-127 concentration in the membranes, the surface roughness of the membranes decreased and hydrophilicity and permeation fluxes increased notably. Furthermore, it was observed that the addition of the Pluronic F-127 polymer into the membranes reduced reversible/irreversible membrane fouling. Additionally, a characterisation of the fouled membranes was performed for the purpose of comprehensively understanding the membrane fouling mechanism caused by microalgal culture.

Encapsulation of Sesbania grandiflora extract in polymeric micelles to enhance its solubility, stability, and antibacterial activity

Clinical applications of Sesbania grandiflora bark extract (SGE) are limited because of its poor water solubility and stability. SGE was loaded in micelles of Pluronics. In vitro and in vivo antibacterial and toxicity tests were investigated using broth dilution and silkworm model. Aqueous solubility of SGE was improved by these micelles. Activity and toxicity of SGE loaded micelles were dependent on type and concentration of Pluronics. The micelles composed of 1:3 SGE to Pluronic F68 (SGE-PF68-13) showed small size (24.95 ± 0.34 nm), narrow PdI (<0.2), high entrapment efficiency (99.63 ± 0.19%) and negative zeta potential (−41.53 ± 0.15 mV). Stability of SGE in SGE-PF68-13 was 10 times higher than the unentrapped SGE. SGE-PF68-13 showed a dose dependent activity and significantly higher therapeutic effect than the unentrapped SGE. It is concluded that encapsulation of SGE in Pluronic micelles can enhance SGE solubility, stability, and antibacterial activity. SGE-PF68-13 is suitable for further study in mammalian animals.

Low-index, smooth Al_2O_3 films by aqueous solution process

We describe low-index porous alumina thin films deposited from aqueous solutions containing flat-Al13 clusters and the nonionic block copolymer Pluronic F127. The films exhibit surface roughness as low as 0.5 nm, a characteristic useful for the fabrication of multilayer optical devices. We have investigated the chemical, optical, and structural properties of the films and their formation by Fourier transform infrared spectroscopy, temperature programmed desorption, spectroscopic ellipsometry, transmission electron microscopy, atomic force microscopy, and X-ray diffraction. By varying the Pluronic F127 concentration, film porosities can be tuned to produce refractive indexes between n = 1.26 and 1.54 (λ = 550 nm).

Small-angle neutron scattering studies of microenvironmental and structural changes of Pluronic micelles upon encapsulation of paclitaxel

Abstract Pluronic micelles represent a novel type of nanocarriers that enhance the therapeutic efficacy of paclitaxel (PTX) by increasing its solubility and circulation time. However, encapsulation or incorporation of a drug influences the micellar structure and subsequently alters the pharmacokinetic behavior of the drug delivery system. In this study, we investigated the structural properties of micelles after micellar solubilization of PTX. Proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) studies showed that PTX was incorporated into the poly (propylene oxide) (PPO) blocks of the micelle cores. Small-angle neutron scattering (SANS) was used to probe changes in the core-shell structure of Pluronic P123 micelles as a function of increasing PTX and Pluronic concentration. Model-independent analyses and cryogenic- transmission electron microscopy (cryo-TEM) confirmed that both pure and PTX-incorporated micelles were spherical. However, an increase in PTX concentration led to a slight increase in the micellar dimension and was associated with the appearance of the larger Pluronic-drug aggregates as confirmed by evaluation of cryo-TEM images. At higher Pluronic concentration and a constant PTX concentration, the dimensions of micelles increased, most likely due to the altered hydrophobic environment promoting the interaction of PPO and poly (ethylene oxide) (PEO) blocks.

Characterizing dispersion and long term stability of concentrated carbon nanotube aqueous suspensions for fabricating ductile cementitious composites

This paper reports a systematic attempt of preparing concentrated aqueous suspensions (up to 0.3wt.%) of different types of carbon nanotubes (CNTs) using Pluronic F-127 for developing ductile cementitious composites. Single-walled and multi-walled nanotubes, both pristine and functionalized, were dispersed in water using a short (1h) and medium energy (80W) ultrasonication process using pluronic at high concentrations (above critical micelle concentration, 1–5wt.%) and also using sodium dodecylbenzene sulphonate (SDBS) for comparison purpose. The CNT suspensions were characterized for agglomerate area, particle size, zeta potential, extractability and long-term storage stability for a period over 4years. The optimum suspensions were used to fabricate cementitious composites and their fracture behavior was characterized. Experimental results suggested that the optimum pluronic concentrations (1% for 0.1% CNT, 5% for 0.2% and 0.3% CNT, all in weight percent) provided highly homogeneous CNT dispersion with very low area of agglomerates. The best dispersion quality was obtained with f-SWCNT/pluronic system, which provided very low agglomerate area (<0.5%), lower CNT bundle size, good quantity of well dispersed nanotubes (up to 50%) and excellent long term storage stability. Cementitious composites fabricated using SWCNT and f-SWCNT suspensions showed ductile fracture behavior and improvement in fracture energy up to 164%.

Effect of Different Pluronic P123 Triblock Copolymer Surfactant Concentrations on SBA-15 Pore Formation

Effect of Different Pluronic P123 Triblock Copolymer Surfactant Concentrations on SBA-15 Pore Formation

The origin of anomalous positive heat capacity change upon micellization of Pluronic triblock copolymer F108 in aqueous solutions: Effect of PEO-PPO diblock impurities

It is well understood that the heat of micellization is monotonically decreased along with increasing temperature. However, it was found (Langmuir 2008, 24, 13858.) that the heat of micellization for Pluronic triblock copolymer in aqueous solutions abnormally increases along with the temperature at high Pluronic concentration region. The origin of this anomalous positive heat capacity change upon micellization of Pluronic F108 in aqueous solutions was explored by using differential scanning calorimetry, chromatography and dynamic light scattering. The impurities of commercial Pluronic F108, used as received, in aqueous solution form large aggregates at the temperatures well below its critical micelle temperature (CMT). At high F108 concentrations (>2.4wt.%), the aggregates almost completely dissociate and then integrate into micelles, resulting in anomalous positive relationship of heat of micellization (ΔH) with critical micelle temperature (CMT). By contrast, at low F108 concentrations (<2.4wt.%), the aggregates do not, or only partly, participate the micellization. When the impurities of F108 are separated and removed by using high performance liquid chromatography, the ΔH of purified F108 aqueous solutions monotonically decreases along with an increase in CMT. That is, a typical linear relationship of ΔH vs. CMT is resumed. It is interesting to find out that the ΔH of 0.05wt.% purified F108 aqueous solution (234.1kJ/mol) is higher than that of unpurified F108 (174.2kJ/mol) by 25.6%.

Superparamagnetic Iron Oxide Nanorod Carriers for Paclitaxel Delivery in the Treatment and Imaging of Colon Cancer in Mice.

A multifunctional magnetic drug delivery system was developed and explored as an efficient and less invasive technique to improve colon cancer diagnosis and therapy in mice. In this system, superparamagnetic iron oxide nanorod cores enhanced passive targeting by bandaging a magnet adjacent to the tumor site, whereas pluronic F127 shell acted as the carrier for paclitaxel. The pluronic-conjugated superparamagnetic iron oxide cores were prepared using the hydrothermal method. It was found that the initial pluronic concentration exerted a significant effect on the distribution of the diameters and lengths of the nanorods. Despite the variation in pluronic concentrations and dimensions of iron oxide products, all the samples exhibited negligible coercivity and remanence, confirming their superparamagnetic characteristics. The pluronic F127-superparamagnetic iron oxide nanocarriers were then prepared by encapsulation of nanorods into pluronic micelles and assessed for paclitaxel loading. Results showed that paclitaxel was incorporated into the core of the micelles through hydrophobic interactions, and that elevating both paclitaxel concentration and temperature increased the loading efficiency. The therapeutic effect of paclitaxel-loaded nanocarriers was then tested in in vitro and in vivo colon cancer models. Compared to docetaxel, the paclitaxel-loaded magnetic nanocarriers significantly suppressed tumor growth and improved survival time of xenograft mice. The accumulated magnetic nanocarriers inside the tumor also served as a contrast agent and enhanced magnetic resonance imaging localization and visualization of the small tumor.

Rational and precise development of amorphous polymeric systems with dapsone by response surface methodology

This work aimed to design dapsone (DAP) amorphous Polymeric Dispersions (PD) using design of experiments (DoE) and response surface methodology (RSM) as optimization tools in order to tailor the biopharmaceutical properties toward its oral delivery. A two-factor, three-level (32) statistical design was implemented to study the influence of input variables (amount of PVP K30 and Pluronic F68) on the equilibrium solubility of DAP of the physical mixture (PM), kneaded (KN) and freeze dried (FD) PDs. Through the analysis, it was found that equilibrium solubility of DAP was improved with increasing of PVP K30, mainly for FD PDs, but decreased with increasing Pluronic F68 concentration. XRD and FTIR spectrum revealed the amorphous characteristic of FD PDs and SEM confirmed the homogeneity of the system leading to enhanced surface area and consequent dissolution rate. The in vitro dissolution rate of PDs was significantly faster compared to DAP and PM, and all the similarity factors (f2) were below 50, demonstrating the differences on the dissolution profiles. The results established the effectiveness of PDs for improvement of dissolution and solubility of DAP and the success in the implementation of DoE and RSM as QbD tools in the design of PDs.

Effect of alcohols on the heat of micellization of Pluronic F88 aqueous solutions

The effects of addition of alcohols (ethanol, 1-propanol, and 1-butanol) to Pluronic F88 aqueous solutions on heat of micellization of Pluronic F88 are carefully examined by using high sensitivity differential scanning calorimeter and dynamic light scattering. With addition of ethanol to Pluronic F88 aqueous solutions, the critical micelle temperature (CMT) increases, the heat of micellization significantly decreases, and the F88 concentration region of the unusual positive heat capacity change (attributed to impurity aggregates) occurs at higher Pluronic F88 concentrations. The addition of ethanol increases the solubility of copolymer and impurities and, hence, hinders the formation of impurity aggregates. Introduction of butanol to F88 aqueous solutions would significantly reduce the CMT but only slightly change the heat of micellization, indicating exothermic interactions of 1-butanol with poly(propylene oxide) blocks. With addition of 1-propanol, both CMT and heat of micellization decrease. With addition of 5 wt.% 1-propanol would substantially expand the F88 concentration region of the unusual positive heat capacity change, indicating a significant dissociation of impurity aggregates into micelles. In addition, the effect of alcohols on the cloud points of Pluronic F88 solutions is also carefully examined and discussed. The enthalpy-entropy compensation phenomenon for the micellization of Pluronic F88 over the concentration regions of negative/positive heat capacity changes is discussed.

Design and optimization of alginate−chitosan−pluronic nanoparticles as a novel meloxicam drug delivery system

ABSTRACTThe inflammation and pain associated with osteoarthritis are treated with nonsteroidal anti‐inflammatory drugs (NSAIDs). This treatment is accompanied by several side effects; therefore local intra articular (IA) NSAID injection can be more efficient and safe than systemic administration or topical use. In this study, alginate−chitosan−pluronic nanoparticles were considered as a new vehicle for IA meloxicam delivery. These novel nanoparticles were prepared using an ionotropic gelation method and were optimized for variables such as alginate to chitosan mass ratio, pluronic concentration, and meloxicam concentration using a 3‐factor in 3‐level Box‐Behnken design. To optimize the formulation, the dependent variables considered were particle size, zeta potential, entrapment efficiency, and mean dissolution time (MDT). The nanoparticles morphology was characterized by FESEM and AFM. The potential interactions of the drug‐polymers were investigated by ATR‐FTIR and DSC, and the delivery profile of meloxicam from the nanoparticles was obtained. The average particle size of the optimized nanoparticles was 283 nm, the zeta potential was −16.9 mV, the meloxicam entrapment efficiency was 55%, and the MDT was 8.9 hours. The cumulative released meloxicam amount from the composite nanoparticles was 85% at pH 7.4 within 96 h. The release profile showed an initial burst release followed by a sustained release phase. The release mechanism was non‐Fickian diffusion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42241.

Microstructure and mechanical properties of carbon nanotube reinforced cementitious composites developed using a novel dispersion technique

The present paper reports the first attempt of developing carbon nanotube (CNT) reinforced cement composites through a short dispersion route using Pluronic F-127 as a novel dispersing agent. Optimum concentrations of Pluronic for various types of CNT were determined, and the influences of Pluronic and CNT on the microstructure and mechanical properties of cementitious composites were thoroughly investigated. Pluronic with optimized defoamer concentration significantly improved the bulk density and mechanical properties of cement mortar. Further, dispersion of 0.1% single walled nanotube (SWNT) improved flexural modulus of mortar by 72% and flexural and compressive strengths by 7% and 19%, respectively after 28days of hydration. Flexural and compressive strengths with functionalized SWNT increased with the hydration period up to 17% and 23% after 56days, respectively. All CNT reinforced samples exhibited significantly higher stiffness, fracture energy and ductility as compared to plain mortar and composite samples prepared using a common surfactant.

Optimization, characterization and evaluation of chitosan-tailored cubic nanoparticles of clotrimazole

The present study deals with improvement of the mucoadhesive properties of monoolein based cubic nanoparticles by incorporating chitosan. Chitosan-tailored cubic nanoparticles were prepared by thin film hydration followed by ultrasonication employing clotrimazole as model drug. The effect of Pluronic F127 fraction and concentration of chitosan on particle size and % mucin binding of the formulations was studied using 2-factor, 3-level, central composite experimental design. The concentration of chitosan was found to influence particle size and % mucin binding of cubic nanoparticles while Pluronic F127 fraction influenced only the % mucin binding. Studies indicated 8.33(%w/w) fraction of Pluronic F127 and 0.17 (%w/v) concentration of chitosan as optimum concentration. Finally, the optimized batch was characterized by polarized light microscopy, small-angle X-ray scattering (SAXS) and transmission electron microscopy. The results unveiled incorporation of chitosan did not disrupt the inner cubic structure of nanoparticles. Peak indexing of SAXS data revealed the coexistence of P-type and D-type cubic phases in nanoparticles. Further, comparative evaluation studies showed significantly higher anti-fungal activity of clotrimazole-loaded chitosan-tailored cubic nanoparticles than conventional suspension of clotrimazole against Candida albicans.

Effect of a Pluronic(®) P123 formulation on the nitric oxide-generating drug JS-K.

O(2)-(2,4-dinitrophenyl)1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate] or JS-K is a nitric oxide-producing prodrug of the arylated diazeniumdiolate class with promising anti-tumor activity. JS-K has challenging solubility and stability properties. We aimed to characterize and compare Pluronic(®) P123-formulated JS-K (P123/JS-K) with free JS-K. We determined micelle size, shape, and critical micelle concentration of Pluronic(®) P123. Efficacy was evaluated in vitro using HL-60 and U937 cells and in vivo in a xenograft in NOD/SCID IL2Rγ (null) mice using HL-60 cells. We compared JS-K and P123/JS-K stability in different media. We also compared plasma protein binding of JS-K and P123/JS-K. We determined the binding and Stern Volmer constants, and thermodynamic parameters. Spherical P123/JS-K micelles were smaller than blank P123. P123/JS-K formulation was more stable in buffered saline, whole blood, plasma and RPMI media as compared to free JS-K. P123 affected the protein binding properties of JS-K. In vitro it was as efficacious as JS-K alone when tested in HL-60 and U937 cells and in vivo greater tumor regression was observed for P123/JS-K treated NOD/SCID IL2Rγ (null) mice when compared to free JS-K-treated NOD/SCID IL2Rγ (null) mice. Pluronic(®) P123 solubilizes, stabilizes and affects the protein binding characteristics of JS-K. P123/JS-K showed more in vivo anti-tumor activity than free JS-K.

Stabilization of Pluronic Gels by Hydrophobically Modified Hydroxyethylcellulose

Hydrophobically modified hydroxyethylcellulose (HM-HEC) of different hydrophobicity has been used to stabilize pluronic gels against dissolution in an aqueous environment. While pluronic by itself dissolves within 1–2 days, the addition of HM-HEC can stabilize part of the gels from dissolving for a period of at least six months. A larger fraction of the gel remains undissolved when utilizing high HM-HEC concentrations and when the degree of hydrophobic modification is increased. The stabilization against fast dissolution makes these systems interesting for drug delivery purposes. The effect of HM-HEC addition on rheological properties of pluronic gels has also been examined. For a low pluronic concentration, the addition of HM-HEC increases the viscosity of the sample, shifts the gel transition to a lower temperature, and reduces the deviscosification of the pluronic gels at high temperatures. When the pluronic concentration is increased, the addition of HM-HEC only affects the sample viscosity at low temperatures.

Influence of Pluronic F127 on the distribution and functionality of inkjet-printed biomolecules in porous nitrocellulose substrates

The distribution of inkjet-printed biomolecules in porous nitrocellulose substrates often results in a non-homogeneous spot morphology commonly referred to as ‘doughnut-shaped’ spots. We have studied the influence of Pluronic F127 (an amphiphilic surfactant) on the functionality of inkjet-printed primary antibody molecules and on the final assay result by performing a one-step antibody binding assay in the nitrocellulose substrate. The primary antibody was printed with and without Pluronic, followed by the addition of double-labelled amplicons as antigen molecules and a fluorophore-labelled streptavidin as detection conjugate. The distribution of the fluorescence intensity down into the nitrocellulose substrate was investigated by confocal laser scanning microscopy in ‘Z’ stacking mode. Each horizontal slice was further analysed by applying a concentric ring format and the fluorescence intensity in each slice was represented in a colour-coded way. The mean and total fluorescence intensity of the antibody binding assay (fluorescent streptavidin) showed a peak at 0.2% (w/v) Pluronic F127. In addition, an improved spot morphology was observed also peaking at the same Pluronic concentration. Subsequently, we investigated the direct influence of Pluronic F127 on the location of the primary antibody molecules by labelling these molecules with the fluorophore Alexa-488. Our results show that upon increasing the concentration of Pluronic F127 in the printing buffer, the spot diameter increased and the number of primary antibody molecules bound in the spot area gradually decreased. This was confirmed by analysing the distribution of fluorescently labelled primary antibody molecules down into the membrane layers.We conclude that a particular ratio between primary antibody and Pluronic F127 molecules in combination with available substrate binding capacity results in an optimal orientation, that is Fab-UP, of the primary antibody molecules. Consequently, an increased number of antigen molecules (in our case the labelled amplicons) and of the fluorescent detection conjugate (streptavidin) will give an optimal signal. Moreover, distribution of the primary antibody molecules was more homogeneous at the optimal Pluronic F127 concentration, contributing to the better spot morphology observed.

Molecular interactions and solubilization of structurally related meso-porphyrin photosensitizers by amphiphilic block copolymers (Pluronics)

The influence of four Pluronics block copolymers (i.e. F68, P123, F127, and L44) on the aggregation and solubilization of five structurally related meso-tetraphenyl porphyrin photosensitizers (PS) as model compounds for use in Photodynamic Therapy of cancer (PDT) was evaluated. Interactions between the PSs and Pluronics were studied at micromolar concentration by means of UV-Vis absorption spectrometry and by kinematic viscosity (υ) and osmolarity measurements at millimolar concentrations. Pluronic micelles were characterized by size and zeta potential (ζ) measurements. The morphology of selected PS-Pluronic assemblies was studied by atomic force microscopy (AFM). While hydrophobic 5,10,15,20-Tetrakis(4-hydroxyphenyl) porphine (THPP) seemed to be solubilized in the Pluronic micellar cores, amphiphilic di(monoethanolammonium) meso-tetraphenyl porphine disulphonate (TPPS2a) was likely bound to the micellar palisade layer. Hydrophilic PSs like 5,10,15,20-Tetrakis (4-trimethylaniliniumphenyl) porphine (TAPP) seemed to form complexes with Pluronic unimers and to be distributed among the micellar coronas. TPPS2a aggregated into a network which could be broken at Pluronic concentration ≫ cmc, but would reconstitute in the presence of tonicity adjusting agents, e.g. sodium chloride (NaCl) or glucose.

Fabrication of PVDF hollow fiber membranes: Effects of low-concentration Pluronic and spinning conditions

Due to the unique properties of amphiphilic Pluronic block copolymers, they have been blended with other polymers such as PVDF to prepare membranes. Considering the stability issue, the strong pore-forming ability of Pluronic F127, and the mechanical strength of the resultant membranes, Pluronic/LiCl mixed additive consisting of a very low concentration of Pluronic has been used in this study. The effects of spinning conditions on PVDF hollow fiber fabrication have also been studied. It is found that the use of merely 0.2wt% of Pluronic is sufficient to impose significant impacts on the morphology, filtration performance, and mechanical properties of the resultant fibers. Hollow fibers spun using higher coagulant temperature, higher take-up speed, and water as the bore fluid exhibit better mechanical properties and filtration performance. PVDF hollow fiber membranes with PWP of 1180L/m2hMPa and MWCO of 5kDa were obtained when spun with optimized spinning conditions and using 3wt% of LiCl and 0.2wt% of Pluronic as the mixed additive. The fibers can withstand a pressure of 0.55MPa from the lumen.