Hydroxypropyl Cellulose Content Research Articles

Anisotropic Single-Domain Hydrogel with Stimulus Response to Temperature and Ionic Strength

Hydroxypropyl cellulose (HPC) is a derivative of cellulose with lyotropic liquid crystal property and thermochromism. We took advantage of HPC and combined it with a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel to fabricate an anisotropic single-domain hydrogel by mechanical shearing. The prepared long-range ordered HPC–PNIPAM hydrogels show bright and uniform interference colors between crossed polarizers, which are stimulus-responsive to both temperature and ionic strength. In particular, the oriented HPC–PNIPAM hydrogel has a wide thermoresponsive range which could be adjusted by the HPC and PNIPAM content in the hydrogel, providing a good solution to the narrow or fixed temperature sensing range of hydrogels.

Mucoadhesive brinzolamide-loaded nanofibers for alternative glaucoma treatment

Despite the advances in the field of pharmaceutical materials and technology, topical administration remains a method of choice for the treatment of eye diseases such as glaucoma, with eye drops being a leading dosage form. Their main disadvantage is a very short drug residence time and thus poor drug bioavailability, leading to the necessity of continuous repeated dosing. Mucoadhesive electrospun nanofibers are promising candidates for overcoming these challenges, while still benefiting from topical ocular administration. As an alternative for eye drops, a nanofibrous drug delivery system (DDS) for the delivery of brinzolamide (BRZ), based on β-cyclodextrin (β-CD), hydroxypropyl cellulose (HPC) and polycaprolactone (PCL), was designed. The results showed β-CD/BRZ guest–host interactions, successful drug incorporation into the nanofibers, and the possibility of more accurate dosing in comparison with the control eye drops. Drug permeation through sheep corneas was almost linear in time, achieving therapeutic concentrations in the receptor medium, and mucoadhesion to sheep eye mucosa was relatively high in case of formulations with high HPC content. All formulations were biocompatible, their mechanical properties were sufficient to handle them without caution and UV irradiation was suitable to reduce bioburden of the fibers matrix, yet no antibacterial properties of BRZ were observed.

A facile method to control the phase behavior of hydroxypropyl cellulose

We report a facile chemical method to convert the hydroxyl groups of hydroxypropyl cellulose (HPC) into carbamates. It was achieved by the reaction of HPC with N-methyl carbamoylimidazole, which is a safe and easy to handle replacement for the particularly hazardous reagent methyl isocyanate. Using a series of HPC with a range of molar substitution of hydroxypropyl groups, we synthesized HPC methylcarbamates showing lower critical solution temperature (LCST) in the range between 94 and 15 °C. A linear dependence of LCST versus methylcarbamate degree of substitution is observed. The lower the initial hydroxypropyl content of HPC, the greater the effect of methylcarbamate on the LCST. Surface tension study showed that methylcarbamate modification has an insignificant effect on the hydrophilic-hydrophobic balance of the macromolecules below LCST unless the molecular substitution of hydroxypropyl groups is so low (0.8) that the native cellulose OH groups can react with N-methyl carbamoylimidazole.

Blends of sodium deoxycholate-based poly(ester ether)urethane ionomer and hydroxypropylcellulose with mucosal adhesiveness

New mucoadhesive blends of sodium deoxycholate-based poly(ester ether)urethane ionomer (PU) and hydroxypropyl cellulose (HPC) are prepared. The presence of the intermolecular interactions between the polymeric components has been investigated by FTIR spectroscopy indicating their miscibility in the solid phase. DSC studies also revealed a single glass transition of the blends, which is indicative of miscibility of PU and HPC in the amorphous phase. The amount of HPC in the blends influences strongly the physicochemical and mucoadhesion/bioadhesion properties. It was found that the value of area attributed to ordered hydrogen bonding (FTIR), the onset temperature values of thermal degradation in N2 flow (TG/DTG), the values of the sorption capacity (Dynamic Vapor Sorption-DVS), the values of the apparent viscosity (rheological measurements) and mucoadhesion/bioadhesion properties increased by increasing the HPC content in the blends. Complex viscosity revealed shear thinning behavior for all the studied solutions evidencing the contributive role of polymer viscoelasticity on mucoadhesion. It was found that both G' and G" increase with an increase in angular frequency and G">G' which is characteristic for liquid-like (sol state) behavior for all blended solutions and this behavior is helpful in the adhesion with mucosa surface. Mucoadhesion of PU/HPC blends was assessed in the stomach mucosa at pH 2.6 and 37 °C. Bioadhesion test was performed at pH 7.4 and 37 °C and revealed a stronger interaction of PU/HPC blends with cellulose membrane than with stomach mucosa. The similar nature of the HPC and cellulose membrane determines additional adhesion forces and implicity high adhesion properties. The HPC component increases the hydrophilicity of the blends as DVS analysis revealed, but also leads to hydrolytic degradation. FTIR spectroscopy analysis was used to evaluate the hydrolytic stability in acid (pH 2.6) and slightly alkaline (pH 7.4) PBS media and a mechanism of degradation has been proposed.

Flexible and Structural Coloured Composite Films from Cellulose Nanocrystals/Hydroxypropyl Cellulose Lyotropic Suspensions

Lyotropic colloidal aqueous suspensions of cellulose nanocrystals (CNCs) can, after solvent evaporation, retain their chiral nematic arrangement. As water is removed the pitch value of the suspension decreases and structural colour-generating films, which are mechanically brittle in nature, can be obtained. Increasing their flexibility while keeping the chiral nematic structure and biocompatible nature is a challenging task. However, if achievable, this will promote their use in new and interesting applications. In this study, we report on the addition of different amounts of hydroxypropyl cellulose (HPC) to CNCs suspension within the coexistence of the isotropic-anisotropic phases and infer the influence of this cellulosic derivative on the properties of the obtained solid films. It was possible to add 50 wt.% of HPC to a CNCs aqueous suspension (to obtain a 50/50 solids ratio) without disrupting the LC phase of CNCs and maintaining a left-handed helical structure in the obtained films. When 30 wt.% of HPC was added to the suspension of CNCs, a strong colouration in the film was still observed. This colour shifts to the near-infrared region as the HPC content in the colloidal suspension increases to 40 wt.% or 50 wt.% The all-cellulosic composite films present an increase in the maximum strain as the concentration of HPC increases, as shown by the bending experiments and an improvement in their thermal properties.

Sol-Gel Synthesis of CaTiO3:Pr3+ Red Phosphors: Tailoring the Synthetic Parameters for Luminescent and Afterglow Applications.

Two sol–gel synthetic routes for the preparation of CaTiO3:Pr3+ red emitting phosphors were compared, with the aim of producing nanostructured materials with tailored luminescence/afterglow properties. The effect of the synthetic parameters, such as the addition of a stabilizer and calcination temperature, on the structural, morphological, and optical properties was investigated. The desired perovskite phase was obtained at a calcination temperature of 800 °C or higher. Although the use of acetic acid as the chelating agent leads to micrometric particles with heterogeneous composition, the presence of hydroxypropylcellulose (HPC) results in smaller, less aggregated particles as well as in a high phase purity. At the highest HPC content, surface Ca-rich impurities were detected, although no segregated Ca-rich phases were detectable by X-ray powder diffraction analyses. Luminescence properties were found to be positively related to the phase purity of the oxide, with the highest quantum yields at temperatures equal to or higher than 1000 °C. On the contrary, persistent luminescence properties were highest at intermediate calcination temperatures and for samples synthesized with acetic acid. Overall, a notable role of oxygen vacancies resulting from local Ca excess was observed, acting as trap levels promoting longer relaxation pathways. Thanks to the small-sized particles and best steady-state luminescent properties due to a substantial decrease of lattice defects, the HPC synthesis is a promising strategy for light-emitting diode applications. On the other hand, the acetic acid synthesis promoted a higher defect density, which is required for an efficient yield of light emission in the long time range and is thus more suitable for afterglow applications.

Interpenetrating network hydrogels with high strength and transparency for potential use as external dressings

Interpenetrating polymer network (IPN) hydrogels composed of gelatin and hydroxypropyl cellulose (HPC) were prepared by successive enzymatic and chemical crosslinking approaches. The hydrogels displayed porous structure and the pore size decreased with the increase of HPC content. Due to the entanglement and interpenetrating between the two crosslinked networks, the IPN hydrogels exhibited excellent mechanical strength and light transmittance. The maximum tensile and tear strengths of the IPN hydrogels reached 3.1 and 5.2MPa, respectively. The water vapor permeability of the IPN hydrogels was within the acceptable range to maintain appropriate moisture for wound healing. The cytotoxicity evaluation indicated that the IPN hydrogels exhibited no toxicity to fibroblast cells. In addition, the hydrogels were loaded with chloramphenicol by pre-soaking in drug solutions to evaluate drug-loading capacity and in vitro release behavior. It was found that the drug loaded hydrogels could act as drug delivery devices to create microbe free microenvironment, which was advantageous for wound healing.

Design and Evaluation of Buccal Patch Containing Combination of Hydrochlorothiazide and Lisinopril

Purpose: The objective of the present study was to formulate and evaluate buccal patches containing combination of lisinopril (LP) and hydrochlorothiazide (HCZ). Approach: Films were fabricated by solvent casting method, using combination of mucoadhesive polymers such as hydroxypropylmethyl cellulose (HPMC), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA) and polyvinyl pyrolidone (PVP) and ethyl cellulose (EC) as backing layer. The patches were evaluated for physicochemical characteristics such as weight, thickness, surface pH, folding endurance, bioadhesive strength, swelling index, drug content, tensile strength, elongation at break, mucoadhesion time, in vitro and ex vivo drug permeation. Results: The IR spectra showed no interaction between drug and polymer. Physicochemical characteristics of all the samples were found to be satisfactory. Swelling of the films increased with increasing content of HPMC or HPC and PVP. Bioadhesive force, tensile strength, percentage elongation and mucoadhesion time increased with higher proportions of HPMC, HPC and PVA. In vitro drug release studies demonstrated slower release of both drugs in formulations with higher amount of HPMC, HPC and PVA. The in vitro drug release data of most formulations best fitted first order model, except for the formulations FA3 and FC. Ex vivo drug permeation studies of formulations through porcine buccal mucosa showed similar results as in vitro. Conclusion: Buccal delivery of this combination can resolve the drawbacks like incomplete absorption in the gut thereby possible improvement in bioavailability, apart from controlled release of the drugs.

Possibility of monitoring granulation by analyzing the amount of hydroxypropylcellulose, a binder on the surface of granules, using ToF-SIMS

The purpose of this study was to clarify the mechanism responsible for high-shear wet granulation using time-of-flight secondary ion mass spectrometry (ToF-SIMS), which can be used for surface chemical mapping. A total of 15 kinds of granules, including hydroxypropylcellulose (HPC) as a binder, were obtained in a model formulation using different granulation conditions, such as the amount of sprayed water and the granulation time. Surface chemical mapping of these granules was then performed using a ToF-SIMS analysis, which distinguishes each component by detecting the specific mass-to-charge ratio (m/z). As a result, we found that HPC got to appear on the surface of granule with proceeding wet granulation. By considering this result, we concluded that the distributions of HPC might be closely related to the progress of granule consolidation and growth in wet granulation. Therefore, the progress of granulation can likely be understood by measuring the content of HPC on the granule surface.

Study on glucose release ability from hydroxypropyl cellulose films

Drug delivery systems based on different glucose and hydroxypropyl cellulose (HPC) ratios were prepared and characterized to check their suitability as controlled drug delivery carriers. The surface polarity and topography were analyzed and correlated with the glucose/HPC ratio and the drug release mechanism. Different mathematical models were used to fit the “in vitro” release data to understand the glucose release mechanism. The in vitro release data analyzed using various kinetic models showed that all the samples were governed by first-order kinetics; however, one sample seems to have a behavior closer to zero-order kinetics. When a higher percentage HPC was added, the release process was described by Fickian diffusion. An anomalous diffusion was correlated with a lower HPC content. The study showed that glucose/HPC is an interesting matrix for the preparation of controlled release systems which can provide a constant glucose dose over a 4-h period.

Miscibility Studies of Hydroxypropyl Cellulose/Poly(Ethylene Glycol) in Dilute Solutions and Solid State

The miscibility of Hydroxypropyl cellulose (HPC)/poly(ethylene glycol) (PEG) blends over an extended range of concentrations in water. The viscosity, ultrasonic velocity, and refractive index of the above blend solutions have been measured at 30°C. The interaction parameters such as and μ proposed by Chee and α proposed by Sun have been obtained using the viscosity data to probe the miscibility of the polymer blends. The values indicated that the blends were miscible when HPC content is more than 40% in the blend. The obtained results have been confirmed by the ultrasonic velocity and refractive index studies. The films of the blends were prepared by solution casting method using water as a solvent. The prepared films have been characterized by analytical techniques such as FTIR, DSC, X-RD, and SEM to probe the miscibility of HPC/PEG blends. The compatibility in the above compositions may be due to the formation of H-bonding between hydroxyl groups of HPC and etheric oxygen atom of PEG molecules.

Study of Pharmaceutical Coatings by Means of NMR Cryoporometry and Sem Image Analysis

Nuclear magnetic resonance (NMR) cryoporometry and scanning electron microscopy (SEM) image analysis have been used to investigate the size and shape distribution of pores in pharmaceutical coatings. The coatings were made from a mixture of hydroxypropylcellulose (HPC) and ethylcellulose (EC). Upon solvent evaporation from a solution consisting of both the polymers, a solid polymer film is formed, which after removal of the water-soluble HPC consists of a skeleton of EC. A change in the amount of HPC enables modification of the water permeability through the films. By means of NMR cryoporometry, the presence of small pores (radius below 400 nm) was revealed with no significant change in the pore size distribution (PSD) as the HPC content in the films were changed. NMR cryoporometry showed the presence of channels of a characteristic 30-nm length scale in the films that contained more than 22% HPC. Below this threshold, the lack of interconnecting channels seems to prevent complete HPC dissolution and thereby the water permeability. SEM image analysis showed pore sizes that ranged from hundreds of nanometers up to few micrometers. Above the 22% threshold, further increase of HPC in the films resulted in an increased pore volume and wider PSD.

Tio2 Paste Formulation for Crack-Free Mesoporous Nanocrystalline Film of Dye-Sensitized Solar Cells

Using a doctor-blade method, a highly viscous titanium dioxide (TiO2) paste was deposited on a glass substrate coated with fluorine doped tin oxide (FTO). The paste was mainly composed of commercially available TiO2 nanoparticles (P25) and hydroxypropyl cellulose (HPC) as organic filler. Varying the content of HPC in the TiO2 paste changed the physical properties of the mesoporous TiO2 layer, particularly its porosity and surface area. From the quantification of dyes on Ti2, layer and the electrochemical impedance spectroscopy (EIS) study of the dye-sensitized solar cells (DSSCs), the surface area of the TiO2 film was found to have decreased. This came with the increase of HPC content while the porosity of the film increased, consistent with the concurrent decrease of short-circuit current density (Jsc) and efficiency (eta). The increased porosity greatly affected the electron transport through the TiO2 film by decreasing the coordination number of the TiO2 particles resulting to a decrease of the electron diffusion coefficient.

Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation

In this study, we have explored the slow (of the order of several hundreds of picoseconds) relaxation dynamics of water associated with the hydration shell of a biocompatible polymer, hydroxypropyl cellulose (HPC)-water mixture as a function of HPC concentration using time-resolved fluorescence spectroscopy. The relaxation dynamics slows down with a progressive increase in HPC content indicating restriction of the relaxation pathway of water molecules specially beyond a cellulose concentration of 20% wherein an isotropic to liquid crystalline cholesteric microscopic phase separation sets in. The activation energy calculated from the temperature dependent solvation dynamics studies also shows a similar trend. The nucleophilic activity of water molecules in these mixtures is determined by measuring the reaction kinetics of solvolysis of benzoyl chloride, and the reaction rate exhibits a marked decrease as the phase separation sets in. The observed results are correlated with a transition between the 'bulk' and 'bound' type of water molecules present in the system.

Studies on swelling kinetics for HPC/PAN thermo‐sensitive blending films

A series of thermo‐sensitive blending films was prepared from hydroxypropylcellulose (HPC) and polyacrylonitrile (PAN). The effects of materials ratio, pH value, and temperature on the swelling velocity of these blending films were studied. At temperatures above the lower critical solution temperature (LCST), different results are found after dipping blend film samples in acid or alkaline solutions, respectively. At a pH value of 1.4, the swelling velocity of HPC/PAN blended films increased with the HPC content. The films' swelling was mainly controlled by polymer chain relaxation. For a pH value of 7.4 the mechanism responsible for the swelling is the water molecules' diffusion. The swelling velocity was also affected by temperature and pH. Copyright © 2009 John Wiley & Sons, Ltd.

Development and in vivo evaluation of novel monolithic controlled release compositions of galantamine hydrobromide as against reservoir technology

The objective of this study is to develop and in vivo evaluation of novel monolithic matrix mini tablets approach to control the release of galantamine hydrobromide (GAH) in comparison with desired release profile to the Innovator formulation Razadyne® ER capsules. The direct compression method was employed for preparation of matrix mini tablets as against reservoir multiparticulate pellets of innovator formulation. The matrix swellings, dissolution similarity, mean dissolution time and dissolution efficiency of formulations were evaluated. It was found that increase in the concentration of high viscosity hydroxypropylcellulose (HPC) results reduction in release rate. The drug release was shown to be pH dependent with faster rate at lower pH. The release of GAH followed first order shifting to dissolution dependent by increase of HPC content. The formulation showed stability of drug release. In vivo prediction was done by Wagner–Nelson method. Prediction errors were estimated for Cmax and area under curve (AUC) and found to be not exceeding 15%. In vivo study in human volunteers confirmed the similarity between test and innovator formulations and pharmacokinetic values were comparable between actual and predicted. These results suggest that novel monolithic matrix approach could be suitable technique to formulate controlled release GAH.

Effect of ethanol on the water permeability of controlled release films composed of ethyl cellulose and hydroxypropyl cellulose

The robustness of controlled release formulations when co-ingested with alcohol is a current concern expressed by regulatory authorities, especially with regard to dose dumping. One such controlled release formulation commonly used is film coating composed of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC). The aim of this study was to investigate how the presence of ethanol in the dissolution medium affects the water permeability of such films. Film samples were prepared in various EC–HPC compositions, and the effect of different ethanol concentrations in the dissolution medium on the permeability was studied using a modified Ussing chamber and tritiated water. It was found that the effect of ethanol on the film permeability varied depending on the composition of the films. The results were interpreted in terms of swelling of the EC in the films, where the swelling increased with increasing ethanol concentration. Thus, for films with low HPC content (non-interconnected pores), the water permeability of the films increased with increasing ethanol concentration as the diffusion through the ethyl cellulose increased due to swelling. However, for films with higher HPC content (having interconnected pores through the films), the permeability decreased, likely due to the swelling of the ethyl cellulose blocking the pores. The interpretation of the results was supported by dynamic mechanic analysis and SEM analysis.

Oriented and low‐density tin dioxide film by sol–gel mineralizing tin‐contained hydroxypropyl cellulose lyotropic liquid crystal for laser‐induced extreme ultraviolet emission

AbstractA series of tin‐doped hydroxypropyl cellulose (HPC) lyotropic liquid crystal (LC) was synthesized using a simple process and their properties were characterized using selective reflection, wide‐angle X‐ray diffraction (WAXD), and the band texture observed under polarized optical microscope. The present preparation is applicable for mass production using large substrate with low cost HPC. A cholesteric lyotropic LC phase was observed for the hybrid solution with higher than 40 wt % HPC. After sol–gel condensation, the HPC‐Sn hybrid LC films were calcined at 400 °C and the as‐prepared product was determined to obtain tin dioxide (SnO2) which was characterized using WAXD. The iridescent color and ∼2 nm structure seen after the condensation disappeared in the as‐prepared SnO2. Scanning electronic microscope images of the SnO2 showed that the HPC content in the HPC‐Sn hybrid played an important role in controlling the SnO2 morphology. A spectrum of relatively monochromatic extreme ultraviolet (13.5 nm) emission was measured in the as‐prepared SnO2 in comparison with bulk tin and inverse opal SnO2. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4566–4576, 2009

Gels from acrylic acid and hydroxypropyl cellulose via free radical polymerization

AbstractA hydrogel from acrylic acid and hydroxypropyl cellulose was made. The percentages of raw materials and crosslinkers were varied and its swelling behavior was evaluated. Some of the gels obtained absorbed more than 300% wt. The gels with higher swelling percentages were characterized by means of IR spectroscopy, differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA), and scanning electron microscopy (SEM). The FTIR showed the presence of the main reactants in the gel, while the DSC showed a phase separation in the gel. This gel is partly biodegradable because of the content of hydroxypropyl cellulose and has the viscoelastic properties of poly(acrylic acid).

Thermal analysis of chitosan and its blends

The present work is concerned with experimental results of DMTA and DSC techniques, which are used to study phase relaxation behavior of chitosan having various DD and its blends with polyvinyl alcohol (PVAL) and hydroxypropylcellulose (HPC). The analysis of DMTA spectra of chitosan leads to recognition of a few molecular relaxations in chitosan and in its blends. A strong effect of water presence on the macromolecular dynamics is observed. Double “wet” relaxations (close to ambient temperature) are observed. Optical film transparency of the chitosan blends with PVAL and HPC allows us to predict good miscibiliry of components in the complex systems. However, unchanged temperatures of the glass transitions of PVAL and isotropization of HPC in the blends indicate separation of components. However, a low content of PVAL or HPC can be molecularly distributed in a chitosan matrix giving a miscible system of good mechanical properties.