Hydroxypropylcellulose Solutions Research Articles

Efficiency of non-protein solutions using hydroxypropyl cellulose on survival of bovine and human oocytes and embryos after vitrification

Vitrification is an alternative method of cryopreservation in ART, resulting in significantly improved survival rates of oocytes and embryos, and with excellent clinical outcomes. To reduce risk of viral contamination, government regulators have stipulated that non-serum substitutes must be used ART. The purpose of this study was to test the efficacy of a synthetic macromolecule, hydroxypropyl cellulose (HPC), for use as a supplement in vitrification solutions. In vitro survival and clinical outcome of bovine and human oocytes and blastocysts after vitrification using non-protein vitrification solutions containing HPC were examined and compared with conventional vitrification method. Four experiments were conducted to assess the efficacy of non-protein VS for oocytes and blastocysts. Four-hundred and twenty bovine oocytes and 300 blastocysts and 154 human oocytes were vitrified by the Cryotec method(Kuwayama, 2013). The solutions for vitrification were supplemented with 0.06 mg/ml HPC or with 10%SSS or with no added macromolecule (NA). Some HPC solutions and SSS solutions were stored at 4ºC or -80ºC for 12months before vitrification. The survival rates of bovine oocytes vitrified in HPC, SSS and NA were 100%, 100% and 86% and the respective blastocyst rates were 22%, 18% and 8%, respectively. The survival rates of bovine blastocysts vitrified in HPC, SSS and NA were 99%, 93% and 88%, respectively.The survival rate of bovine oocytes vitrified in HPC solutions stored for 12 months at 4°C or -80°C was 100%; the rates for those vitrified in SSS solutions were somewhat lower than HPC. The survival rates of human oocytes vitrified in HPC, SSS and NA were 100%, 98% and 92%, respectively. High morphological in vitro survival and growth of bovine and human oocytes, and also bovine blastocysts after vitrification using the solutions containing HPC suggest that this supplement can be effective for human oocytes and embryos vitrification.

Study of Casting Self-Colored Liquid Crystalline Solid Films of Hydroxypropyl Cellulose

Solutions of lyotropic cholesteric liquid crystalline hydroxypropyl cellulose (HPC) in water would be self-colored due to the selective reflection of visible light, depending on the solution concentration. Colored coating of the liquid crystalline aqueous HPC solutions was attempted to apply. HPC solid films were found which could cast from the liquid crystalline solutions at different conditions such as solution concentration and different drying temperature. Experiments show that both solution concentration and cooling velocity play an important effect in controlling the color of HPC films.

Influence of the elasticity of cellulose solutions on the dispersion of carbon black agglomerates

A counter-rotating rheo-optical tool was used to study the dispersion process of carbon black agglomerates in different suspending media, including the solutions of different types of cellulose, aqueous hydroxypropylcellulose solutions, and polyisobutylene. For each suspending fluid, the mechanism of dispersion (erosion or rupture) was identified, and the macroscopic critical shear stress necessary for dispersion was measured. Checking that the impacts of fluid infiltration and agglomerate size on the macroscopic critical shear stress for dispersion were negligible in our case, we showed that elasticity is a major factor acting on dispersion physics. At a constant viscosity, the higher the elasticity is, the more difficult dispersion is, giving higher critical shear stresses for initiating dispersion. There is a linear correlation between the suspending fluid elasticity and this critical shear stress, independent of temperature. An explication of the influence of matrix elasticity on agglomerate dispersion based on recent numerical simulation is given.

Migration and alignment of spherical particles in sheared viscoelastic suspensions. A quantitative determination of the flow-induced self-assembly kinetics

Flow-Induced Self-Assembly (FISA) is the flow-driven formation of ordered structures in complex fluids. In this paper the effect of shear flow on the microstructure formation of dilute sphere suspensions in a viscoelastic fluid has been studied experimentally by optical microscopy techniques. The system is formed by Polymethylmethacrylate beads suspended in 20wt.% aqueous solutions of Hydroxypropylcellulose at volume fractions ranging between 0.1% and 1.0%. Experiments show that, under the action of flow, beads migrate from the bulk to the shear walls, there forming strings aligned along the flow direction. Strings grow with time eventually reaching a steady-state final length. The alignment kinetics have been quantified by means of an alignment factor, which is a measure of the average length of the strings. The experimental results indicate that both shear rate and particle concentration are relevant factors in determining the alignment factor kinetics. In particular, it is shown that, upon increasing shear rate, strings grow both faster and longer. As a consequence, the characteristic time of the overall alignment process remains roughly constant. It is also shown that an increase in particle volume fraction determines effects similar to an increase of shear rate.

The effects of carbon nanofibre on the liquid crystalline behaviour and cholesteric pitch of aqueous solutions of hydroxypropyl cellulose

The liquid crystalline behaviour of aqueous solutions of hydroxypropyl cellulose (HPC_aq.) in which a small amount of carbon nanofibres (CNF) are dispersed (HPC_ aq./CNF) was investigated. Small spherical anisotropic droplets showing a biphasic state were found in the sample in which f 2 = 45.8 wt%, where f 2 is the weight fraction of HPC and CNF based on the total solids content. A preferential interaction is suggested between the hydrophobic surfaces of CNF and the spherical anisotropic droplets, or domains, of HPC. The samples of HPC_aq./CNF with f 2 lying between 59.4 wt% and 67.3 wt% showed the iridescence characteristic of the cholesteric phase. It was found that the cholesteric pitch multiplied by the averaged refractive index of HPC_aq./CNF was shorter than that of HPC aq. at a given value of weight fractions f 1 and f 2, where f 1 was the weight fraction of polymer based on the weight of the solution alone.

Simultaneous quantification of polymeric and surface active stabilizers of nanosuspensions by using near-infrared spectroscopy

Nanosuspension technology is an attractive approach for the formulation and solubility enhancement of poorly water-soluble drug compounds. The technology requires adequate excipients for stabilizing the suspensions during nanogrinding and storage. This study aimed at establishing a near-infrared (NIR) method for assaying simultaneously the two nanoparticle stabilizers, sodium dodecyl sulphate (SDS) and hydroxypropylcellulose (HPC), in miconazole nanosuspensions. Second derivative of NIR signals was used to establish calibration curves in concentration ranges of interest of SDS (0.03–0.3%) and HPC (0.75–7.5%). The suitability and applicability of the NIR method was verified by evaluating the linearity, accuracy, precision, and specificity of the obtained data. The method was then used to quantify indirectly the amount of SDS and HPC adsorbed onto miconazole nanoparticles. Within the concentration range of interest, SDS adsorption increased up to 122 µg/m2 (4.2 × 10−7 mol/m2) with increasing SDS concentration, and HPC adsorption was in the range of 800–1000 µg/m2 (21–27 × 10−7 mol/m2) for nanosuspensions containing nominally 5% HPC and 12.5% or 20% miconazole. Interestingly, some of the adsorbed HPC was displaced upon increase of SDS concentration and adsorption. The data were also confirmed by surface tension measurements of aqueous solutions of SDS and HPC and nanosuspension supernatants. The availability of a fast and nondestructive method for quantifying simultaneously the adsorption of two stabilizers onto nanoground particles may not only speed up nanosuspension development, but also provide insight into the mechanisms of nanoparticle stabilization regarding competitive adsorption and electrostatic versus steric stabilization.

Evaluation of Models for Predicting Spray Mist Diameter for Scaling-Up of the Fluidized Bed Granulation Process

We evaluated models for predicting spray mist diameter suitable for scaling-up the fluidized bed granulation process. By precise selection of experimental conditions, we were able to identify a suitable prediction model that considers changes in binder solution, nozzle dimension, and spray conditions. We used hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), or polyvinylpyrrolidone (PVP) binder solutions, which are commonly employed by the pharmaceutical industry. Nozzle dimension and spray conditions for oral dosing were carefully selected to reflect manufacturing and small (1/10) scale process conditions. We were able to demonstrate that the prediction model proposed by Mulhem optimally estimated spray mist diameter when each coefficient was modified. Moreover, we developed a simple scale-up rule to produce the same spray mist diameter at different process scales. We confirmed that the Rosin-Rammler distribution could be applied to this process, and that its distribution coefficient was 1.43-1.72 regardless of binder solution, spray condition, or nozzle dimension.

Hydroxypropylcellulose templated synthesis of surfactant-free poly(acrylic acid) nanogels in aqueous media

Abstract We report the synthesis and study of surfactant-free poly(acrylic acid) (PAA) nanogels using hydroxypropylcellulose (HPC) as a template in aqueous HPC solutions at room temperature or above. Through the hydrogen bonding interaction of acrylic acid (AA) with hydroxypropylcellulose (HPC), AA absorbed on the HPC polymer chains and triggered the phase transition of HPC at a lower temperature, with increasing AA concentration, than the HPC intrinsic phase transition temperature 41 °C. As AA polymerized to form PAA, the much stronger interpolymer hydrogen bonding triggered the phase transition of HPC at a temperature around room temperature, causing HPC coil-global phase transition to collapse and form nanospheres at room temperature, PAA hydrogen-bonded HPC chains collapsed and formed nanogels chemically crosslinked by poly(ethylene glycol) diacrylate (PEGDA) or methylenebisacrylamide (BIS). The results showed that all the PAA nanogels demonstrated a narrow size distribution with diameters ranging from 60 nm to 600 nm.

An investigation on the correlation between drug dissolution properties and the growth behaviour of granules in high shear mixer

The aim of this study was to investigate the correlation between the growth behaviour and in-vitro dissolution rate of water-insoluble drugs prepared with high-shear wet granulation. Granules containing nimodipine, microcrystalline cellulose, low-substituted hydroxypropylcellulose and aqueous solution of hydroxypropylcellulose were prepared and the effects of independent process variables, including impeller speed and liquid-to-solid ratio were taken into consideration. The mean granule size, granule-size distribution (GSD), porosity and surface properties were monitored at different kneading times to identify the granule-growth mechanisms simultaneously. A computer-based method was applied to simulate the dissolution behaviour of polydisperse granules based on the GSD data. The in-vitro dissolution rate of drug was high for the early stages of granulation and sharply decreased when coalescence and consolidation of granules started, approaching a flat and low level when granules were sufficiently consolidated. The simulated dissolution results were in agreement with experimental observations and were significantly affected by the GSD, porosity and surface properties of granules during the granulation process. Moreover the GSD was directly related to the granule-growth behaviour and mechanisms. In general, it was concluded that the dissolution properties of nimodipine basically correlated with the growth behaviour of granules in a high-shear mixer. The simulation method based on GSD can be used as a convenient and rapid way to predict the dissolution properties for formulation development and granulation optimization.

Dissolution and Solid-State Characterization of Poorly Water-Soluble Drugs in the Presence of a Hydrophilic Carrier

The aim of this study was to investigate the effects of a hydrophilic carrier on the solid-state and dissolution characteristics of poorly water-soluble drugs. Three poorly water-soluble drugs, ibuprofen, carbamazepine, and nifedipine, were studied in combination with hydroxypropyl cellulose (HPC), a low molecular weight hydrophilic polymer, without the use of solvent. A 1:1 drug-polymer ratio was used to evaluate the percent drug release, crystallinity, and wettability. A drug-polymer ratio of 1:4 was also used in co-grinding process to evaluate the effect of polymer levels on drug release. Dissolution studies were carried out in deionized water. Mean dissolution time (MDT) was calculated, and statistical analysis of MDTs was done following a single factor one-way analysis of variance. The dissolution rate of the drugs was enhanced by several folds by the simple process of co-grinding with HPC. X-ray diffraction studies were done to investigate the effects of physical and co-ground mix with HPC on the crystallinity of the drugs, which indicated a partial loss in crystallinity upon grinding. Differential scanning calorimetry studies were performed in order to identify possible solid-state interactions between the respective drugs and HPC. Wettability of the drugs by a 0.5% aqueous HPC solution was compared with that of water and n-hexane using the "Washburn method." Increased wetting and hydrophilization of the drugs by HPC, enlarged surface area due to particle size reduction, and a decrease in the degree of crystallinity were identified as the likely contributors to dissolution rate enhancement.

Structural evolution of liquid-crystalline solutions of hydroxypropyl cellulose and hydroxypropyl cellulose-based nanocomposites during flow

The phase state and orientation and dissipative characteristics of biphasic LC HPC-water solutions and filled systems formed on their basis during shear flow are studied by various methods. The concentration of solutions is selected on the basis of the corrected phase diagram constructed with the use of optical interferometry. Flow curves and concentration dependences of viscosity provide additional information about the phase state and structure of the samples and the role of fillers in the rheological properties of solutions. X-ray diffraction data are obtained with the use of a Couette cell consisting of two coaxial capillaries. In the case of a clay suspension in water, practically no orientation is attained. However, in the isotropic 30% solution, clay particles easily orient, a result that indicates an important role of the viscoelasticity of a medium in the orientation process. The development of orientation of HPC macromolecules and clay particles in relation to the shear rate is analyzed separately for systems with the biphasic matrix (LC + isotropic phase). In addition, the time decay of the orientation parameter during relaxation is investigated. It is shown that higher shear rates cause a more rapid relaxation of orientation, for which recovery of the cholesteric helix typical for LC solutions of cellulose derivatives in the equilibrium state plays an important role. Order parameters (separately for the two components) are calculated, and their evolution with the shear rate and total deformation is investigated for systems containing clay nanoparticles (also the structure-active component) in LC solutions. On the basis of these data, it is hypothesized that clay particles form the columnar mesophase, which, under certain conditions, may transform into the discotic mesophase. This transition is responsible for a certain decrease in the order parameter of HPC apparently due to the instability effect of the director. It is found that shearing substantially affects the structure of the system composed of two mesophase species; specifically, it either facilitates the reinforcement of one of them or provokes structural transitions.

A new approach for patterning epiclon-based polyimide precursor films using a lyotropic liquid crystal template

Blends of hydroxypropyl cellulose (HPC) in lyotropic phase have been prepared with a new epiclon-based poly(amic acid) (PAA) in different ratios. The detailed surface morphology of the PAA/HPC films was examined by polarized light microscopy (PLM) and atomic force microscopy (AFM). Besides the specific interactions, such as the hydrogen bonds between PAA and the liquid crystalline component, a slight cross-linking produced in the PAA structure by UV irradiation stabilized the resulting morphology. The effect of UV exposure and the influence of the HPC component weight ratio on the morphology developed by the PAA/HPC blends were investigated. The band texture, typical for lyotropic HPC solutions, evidencing different intensities and dimensions, is observed from atomic force microscopy images in PAA/HPC, being distinguished even at high PAA content and is also maintained after HPC removal with a selective solvent, namely acetone. These results lie at the basis of future investigations concerning high performance mixed alignment layers used in display devices or cell culture substrates with tuned morphology.

Utilization of hydroxypropyl cellulose for green and efficient synthesis of silver nanoparticles

Hydroxypropyl cellulose samples having different molar substitution were prepared through alkalization of cellulose followed by etherification reaction with propylene oxide. Factors affecting hydroxypropyl cellulose preparation like alkali concentration, propylene oxide concentration as well as etherification reaction temperature and duration were extensively studied. The prepared hydroxypropyl cellulose samples were characterized by measuring their molar substitution and then were tried for their water solubility which showed that samples having molar substitution of 0.4 or higher are completely water soluble. The obtained hydroxypropyl cellulose samples were used in the preparation of silver nanoparticles through reduction of silver nitrate. UV–vis spectra of the prepared silver nanoparticles reveal that full reduction of silver ions to silver nanoparticles takes place at pH 12.5. Optimum conditions for conversion of silver ions to silver nanoparticles are to use 0.3% solution of hydroxypropyl cellulose having molar substitution of 0.42, carrying out the reaction at 90°C for 90min.

A Kinetic Study of the Polymorphic Transformation of Nimodipine and Indomethacin during High Shear Granulation

The objective of the present study was to investigate the mechanism, kinetics, and factors affecting the polymorphic transformation of nimodipine (NMD) and indomethacin (IMC) during high shear granulation. Granules containing active pharmaceutical ingredient, microcrystalline cellulose, and low-substituted hydroxypropylcellulose were prepared with ethanolic hydroxypropylcellulose solution, and the effects of independent process variables including impeller speed and granulating temperature were taken into consideration. Two polymorphs of the model drugs and granules were characterized by X-ray powder diffraction analysis and quantitatively determined by differential scanning calorimetry. A theoretical kinetic method of ten kinetic models was applied to analyze the polymorphic transformation of model drugs. The results obtained revealed that both the transformation of modification I to modification II of NMD and the transformation of the α form to the γ form of IMC followed a two-dimensional nuclei growth mechanism. The activation energy of transformation was calculated to be 7.933 and 56.09 kJ·mol(-1) from Arrhenius plot, respectively. Both the granulating temperature and the impeller speed affected the transformation rate of the drugs and, in particular, the high shear stress significantly accelerated the transformation process. By analyzing the growth mechanisms of granules in high-shear mixer, it was concluded that the polymorphic transformation of NMD and IMC took place in accordance with granule growth in a high-shear mixer.

Thermo sensitive behavior of cellulose derivatives in dilute aqueous solutions: From macroscopic to mesoscopic scale

Thermal behaviors of thermo sensitive hydroxypropyl cellulose (HPC), methyl cellulose (MC) and methyl hydroxypropyl cellulose (MHPC) solutions have been investigated in dilute regime of concentration (C<C*) by means of optical density (OD), Quasi Elastic Light Scattering (QELS) and Pyrene Fluorescence Spectroscopy (PyFS) measurements. The importance of controlling the rate of a temperature sweep regarding to the kinetic of association has been demonstrated. MHPC copolymer exhibits only one thermal transition at macroscopic scale (OD and QELS) but two distinct thermal transitions have been evidenced at mesoscopic scale (PyFS) suggesting a double association step for each thermo associative group (i.e. hydroxypropyl and methyl). In HPC/MC mixture, HPC undergoes its own thermal transition. The presence of MC leads to a shift of the temperature of HPC precipitation toward higher temperature even in dilute regime.

Dual-stimuli sensitive nanogels fabricated by self-association of thiolated hydroxypropyl cellulose

A new type of cellulose derivative was synthesized by means of conjugating cysteamine to hydroxypropyl cellulose (HPC) and the degree of thiol groups could be controlled by the feed ratio of the reactants. The thiolated HPC (HPC–SH) maintains the thermosensitivity of HPC and the thiol groups on the HPC chain can be oxidized to disulfide bonds. Cytotoxity tests performed on MG-63 cells proved that HPC–SH is not harmful to the cells. Nanogels can be fabricated by the self-association of HPC–HS in the solution at 45 °C and then oxidation of thiol groups to disulfide bonds occurs to stabilize the associated structure. The crosslinking degree of the nanogels could be controlled by the substitution degree of thiol groups (–SH) in the thiolated HPC. The hydrodynamic radius of the nanogels can be tuned by adjusting the degree of crosslinking and the concentration of the initial thiolated HPC solution in the self-association process. The hydrodynamic radius of the nanogels can be changed with the temperature and the dissociation process can happen by adding the reducing agent dithiothreitol (DTT). The dual-stimuli sensitive nanogels may have potential applications in controlled drug release, transfer switch device and sensors.

Dielectric Properties of the Free Water in Hydroxypropyl Cellulose

We performed dielectric measurements of aqueous solutions of hydroxypropyl cellulose (HPC) with various concentrations in the temperature range between 25 °C and -20 °C. A primary relaxation process due to the motion of free water restricted by HPC molecules is observed at GHz region. The relaxation time and shape parameter of the primary process strongly depend on the concentration of HPC. The change of the dielectric relaxation parameters is interpreted by the results of the formation of a cholesteric phase structure of the HPC molecules.

Phase equilibria in solutions of cellulose derivatives and the rheological properties of solutions in various phase states

Phase equilibria in solutions of hydroxypropyl cellulose in such solvents as water, propylene glycol, poly(ethylene glycols) of various molecular masses, triethyl citrate, and DMSO are analyzed. The phasetransition lines are constructed with the use of microinterference and polarization microscopy methods. In a certain temperature-concentration range, all solutions undergo a sequence of transitions typical for solutions of stiff-chain crystallizable polymers: isotropic and LC states separated by the two-phase corridor and, in some cases, the crystalline state. Of special interest are systems in which the superposition of amorphous (with the LCST or UCST), LC, and crystalline equilibria is realized. The features of the phase states of solutions are compared with the physicochemical characteristics of solvents and the intensity of their interaction with hydroxypropyl cellulose macromolecules. Solutions occurring in various phase states are tested by rheological methods. These solutions demonstrate the typical rheological behavior of anisotropic solutions: the presence of yield stress and the extremum concentration dependence of viscosity with a maximum, when the LC phase appears, and a minimum, when it transforms into the 100% phase. In the case of single-phase solutions, viscosity increases with concentration, while for two-phase solutions, viscosity decreases with an increase in the fraction of the LC phase. The rheological data are found to be sensitive to phase transitions observed in solutions.

Dissipative crystallization of aqueous solutions of hydroxypropyl cellulose

Drying dissipative structures of aqueous solutions of hydroxypropyl cellulose, their viscosities of 2 wt.% solutions ranging from 2 to 2,000 mPa.s were studied on a cover glass, a watch glass, and a Petri glass dish. The thickness profile of the dried film shows the coexistence of a low round hill and a high broad ring on a cover glass. The broad ring size increased as molecular weight and/or concentration of the polymers increased on a cover glass and a watch glass. Microscopic drying crystal patterns of HPC changed as a function of the distance from the film center, which is one of the typical results of the dissipative crystallization. Rod-like microscopic drying patterns originated in the cholesteric liquid crystalline structures were observed. The rods oriented mainly parallel and in some case perpendicularly to the radial direction of the dried film except the central area, where the rods distributed at random. These orientation effects were significant for low molecular weight samples and in a watch glass.

Thermodynamics of mixtures and solutions of hydroxypropylcellulose with poly(ethylene glycol)

Differential scanning calorimetry, X-ray diffraction analysis, polarization microscopy, methods of cloud points and static sorption, and a polarization-photoelectric installation were used to make a thermodynamic analysis of systems constituted by hydroxypropylcellulose, poly(ethylene glycols), and water. The thermodynamic parameters obtained were correlated with phase diagrams of these systems.