orabase and hydroxyethylcellulose

With the growing environmental concerns and an emergent demand, a growing attention is turned to eco-friendly superabsorbent hydrogels instead of synthetic counterparts. Hydrogels based on cellulose derivatives can absorb and retain a huge amount of water in the interstitial sites of their structures, stimulating their uses in various useful industrial purposes. In this work, cross-linked superabsorbent composite hydrogel films (CHF) were designed, manufactured and characterized, by taking advantage of the combination of carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and newly developed regenerated cellulose (RC) spheres. RC with sphere-like shape was successfully prepared using a green method based on cold phosphoric acid-mediated dissolution of microcrystalline cellulose (MCC) followed by regeneration process using water as anti-solvent. Prior to be used, the morphological and structural properties of RC spheres, with an average diameter of 477 ± 270 nm, were examined by SEM, AFM, XRD, FTIR and TGA techniques. CHF crosslinked with citric acid were, in fact, prepared by solvent casting method with different RC weight fractions (i.e. 0, 2.5, 5, 10 and 15 wt%), then the crosslinking reaction was triggered by thermal treatment at 80 °C during 8 h. Prepared CHF were then characterized in terms of their structural, thermal, tensile and transparency properties. Swelling tests were carried at three different aqueous media (i.e. with a pH = 3, 6.4 or 11) to evaluate the water retention capacity of hydrogel films, as well as, the pH effect on their swelling and hydrolytic degradation properties. Collected results reveal that CHF with low RC content (i.e. RC weight fraction of 2.5 or 5 wt%) have the best tensile and swelling properties, with a tensile strength and a swelling capacity (at pH = 6.4) up to 95 MPa and 4000%, respectively.

Topics: Carboxymethylcellulose Sodium; Cellulose; Hydrogels; Hydrogen-Ion Concentration; Hydrolysis; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Phosphoric Acids; Phosphorus; Solvents; Spectroscopy, Fourier Transform Infrared; Tensile Strength; Water; X-Ray Diffraction

In the last years, the production of ethanol fuel has started to change with the introduction of second-generation ethanol (2 G Ethanol) in the energy sector. However, in Brazil, the process of obtaining 2 G ethanol did not reach a basic standard to achieve relevant and economically viable results. Several studies have currently been addressed to solve these issues. A critical stage in the bioethanol production is the deployment of efficient and stable enzymes to catalyze the saccharification step into the process of biomass conversion. The present study comprises a screening for genes coding for plant biomass degradation enzymes, followed by cloning a selected gene, addressing its heterologous expression, and characterizing enzymatic activity towards cellulose derived substrates, with a view to second-generation ethanol production. A cDNA database of the Cotton Boll Weevil, Anthonomus grandis (Coleoptera: Curculionidae), an insect that feeds on cotton plant biomass, was used as a source of plant biomass degradation enzyme genes. A larva and adult midgut-specific β-1,4-Endoglucanase-coding gene (AgraGH45-1) was cloned and expressed in the yeast Pichia pastoris. Its amino acid sequence, including the two catalytic domains, shares high identity with other Coleoptera Glycosyl Hydrolases from family 45 (GH45). AgraGH45-1 activity was detected in a Carboxymethylcellulose (CMC) and Hydroxyethylcellulose (HEC) degradation assay and the optimal conditions for enzymatic activity was pH 5.0 at 50 °C. When compared to commercial cellulase from Aspergillus niger, Agra GH45-1 was 1.3-fold more efficient to degrade HEC substrate. Together, these results show that AgraGH45-1 is a valid candidate to be engineered and be tested for 2 G ethanol production.

Topics: Animals; Carboxymethylcellulose Sodium; Cellulose; DNA, Complementary; Ethanol; Glycoside Hydrolases; Weevils

It was the aim of this study to assess in vitro methods for the characterization of mucoadhesive hydrogels for their potential to predict the residence time on human buccal mucosa.. Mixtures of hydrogels comprising hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (CMC), xanthan gum (XTGM), hyaluronic acid sodium salt (HA), sodium alginate (ALG), carbopol (CP) as well as polycarbophil (PCP) and porcine mucus were analysed for relative rheological synergism. Furthermore, hydrogels were characterized for their texture and mechanical properties. For the assessment of mucoadhesive strength of formulations tensile studies were performed on porcine buccal mucosa. To facilitate a direct comparability of data the residence time of stained hydrogels was determined ex vivo on porcine buccal mucosa and in the oral cavity of volunteers.. The extent of relative rheological synergism was in good agreement with data from in vivo residence time studies. Results of tensile studies were further effected by textural properties of hydrogels leading to a restricted correlation with data from the in vivo experiment. The resistance towards removal by artificial saliva flow ex vivo revealed the highest correlation to the in vivo experiment with increasing mucosal residence time in the rank order CP < HEC, HA, ALG, PCP < CMC < XTGM.. This overview of measurement principles to predict the residence time of hydrogels for buccal application in humans may be a potent tool for the development of semisolid intraoral formulations.

Topics: Acrylic Resins; Adhesives; Administration, Buccal; Adult; Alginates; Animals; Carboxymethylcellulose Sodium; Cellulose; Correlation of Data; Drug Compounding; Drug Delivery Systems; Humans; Hyaluronic Acid; Hydrogels; In Vitro Techniques; Mouth; Mouth Mucosa; Polysaccharides, Bacterial; Swine; Young Adult

Chronotherapeutically programmed hydroxyethylcellulose (HEC) based compression coated doxazosin tablets were prepared and the influence of disintegrants croscarmellose sodium, L-hydroxypropylcellulose (L-HPC), gellan gum on drug release and in vivo performance were investigated. Infrared spectroscopy and differential scanning calorimetric studies did not indicate any excipient incompatibility in the tablets. The disintegrants induced a continuous water influx resulting in a rapid expansion of the membrane. The subsequent formation of fractures into the coats leads to a fast drug release after an initial lag time. Release rates indicated that croscarmellose sodium and L-HPC were directly proportional to their concentration in the formulations. In vitro optimized croscarmellose sodium-HEC matrix showed significantly faster (p < 0.05) drug release (t90% = 46 min) after an initial lag of 243 min. Disintegrant-HEC blended matrices were found significantly superior (p < 0.05) in terms of in vitro release and bioavailability in comparison to plain HEC matrices. Drug release kinetics followed modified power law and Weibull model (r > 0.99). The mechanism involved in release was anomalous transport and super case II transport with matrix swelling. The pulsatile tablets showed no changes either in physicochemical appearance, drug content or in dissolution pattern during its accelerated stability studies.

Topics: Animals; Biological Availability; Blood; Calorimetry, Differential Scanning; Carboxymethylcellulose Sodium; Cellulose; Chemistry, Pharmaceutical; Doxazosin; Humans; Rabbits; Solubility; Tablets

The aim of this study was to characterize the swelling and floating behaviors of gastroretentive drug delivery system (GRDDS) composed of hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (NaCMC) and to optimize HEC/NaCMC GRDDS to incorporate three model drugs with different solubilities (metformin, ciprofloxacin, and esomeprazole). Various ratios of NaCMC to HEC were formulated, and their swelling and floating behaviors were characterized. Influences of media containing various NaCl concentrations on the swelling and floating behaviors and drug solubility were also characterized. Finally, release profiles of the three model drugs from GRDDS formulation (F1-4) and formulation (F1-1) were examined. Results demonstrated when the GRDDS tablets were tested in simulated gastric solution, the degree of swelling at 6 h was decreased for each formulation that contained NaCMC in comparison to those in de-ionized water (DIW). Of note, floating duration was enhanced when in simulated gastric solution compared to DIW. Further, the hydration of tablets was found to be retarded as the NaCl concentration in the medium increased resulting in smaller gel layers and swelling sizes. Dissolution profiles of the three model drugs in media containing various concentrations of NaCl showed that the addition of NaCl to the media affected the solubility of the drugs, and also their gelling behaviors, resulting in different mechanisms for controlling a drug's release. The release mechanism of the freely water-soluble drug, metformin, was mainly diffusion-controlled, while those of the water-soluble drug, ciprofloxacin, and the slightly water-soluble drug, esomeprazole, were mainly anomalous diffusion. Overall results showed that the developed GRDDS composed of HEC 250HHX and NaCMC of 450 cps possessed proper swelling extents and desired floating periods with sustained-release characteristics.

Topics: Carboxymethylcellulose Sodium; Cellulose; Drug Carriers; Drug Liberation; Gastrointestinal Tract; Solubility

Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

Topics: Animals; Carboxymethylcellulose Sodium; Cariostatic Agents; Cattle; Cellulose; Dental Caries; Dental Enamel; Dentifrices; Gels; Methylcellulose; Microradiography; Minerals; Protective Agents; Random Allocation; Saliva, Artificial; Sodium Fluoride; Tooth Abrasion; Tooth Remineralization; Toothbrushing

An extracellular alkaline carboxymethycellulase (CMCase) from Bacillus subtilis was purified by salt precipitation followed by anion-exchange chromatography using DEAE-Sepharose. The cell-free supernatant containing crude enzyme had a CMCase activity of 0.34 U/mg. The purified enzyme gave a specific activity of 3.33 U/mg, with 10-fold purification and an overall activity yield of 5.6%. The purified enzyme displayed a protein band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular size of 30 kDa, which was also confirmed by zymogram analysis. The enzyme displayed multisubstrate specificity, showing significantly higher activity with lichenan and β-glucan as compared to carboxymethylcellulose (CMC), laminarin, hydroxyethylcellulose, and steam-exploded bagasse, and negligible activity with crystalline substrate such as Avicel and filter paper. It was optimally active at pH 9.2 and temperature 45°C. The enzyme was stable in the pH range 6-10 and retained 70% activity at pH 12. Thermal stability analysis revealed that the enzyme was stable in temperature range of 20°C to 45°C and retained more than 50% activity at 60°C for 30 min. The enzyme had a Km of 0.13 mg/ml and Vmax of 3.38 U/mg using CMC as substrate.

Topics: Bacillus subtilis; beta-Glucans; Carboxymethylcellulose Sodium; Cellulose; Chromatography, Ion Exchange; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Glucans; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Polysaccharides; Substrate Specificity; Temperature

The present study investigated the effects of fluoride (F) concentration, lesion baseline severity (ΔZ(base)) and mineral distribution on lesion progression. Artificial caries lesions were created using three protocols [methylcellulose acid gel (MeC), hydroxyethylcellulose acid gel (HEC), carboxymethylcellulose acid solution (CMC)] and with low and high ΔZ(base) groups by varying demineralization times within protocols. Subsequently, lesions were immersed in a demineralizing solution for 24 h in the presence of 0, 1, 2 or 5 ppm F. Changes in mineral distribution characteristics of caries lesions were studied using transverse microradiography. At baseline, the protocols yielded lesions with three distinctly different mineral distributions. Secondary demineralization revealed differences in F response between and within lesion types. In general, lowΔZ lesions were more responsive to F than highΔZ lesions. LowΔZ MeC lesions showed the greatest range of response among all lesions, whereas highΔZ HEC lesions were almost unaffected by F. Laminations were observed in the presence of F in all but highΔZ HEC and CMC lesions. Changes in mineral distribution effected by F were most pronounced in MeC lesions, with remineralization/mineral redeposition in the original lesion body at the expense of sound enamel beyond the original lesion in a dose-response manner. Both ΔZ(base) and lesion mineral distribution directly impact the F response and the extent of secondary demineralization of caries lesions. Further studies - in situ and on natural white spot lesions - are required to better mimic in vivo caries under laboratory conditions.

Topics: Acetic Acid; Animals; Apatites; Calcium Fluoride; Calcium Phosphates; Carboxymethylcellulose Sodium; Cariostatic Agents; Cattle; Cellulose; Dental Enamel; Disease Progression; Dose-Response Relationship, Drug; Durapatite; Fluorides; Hydrogen-Ion Concentration; Lactic Acid; Methylcellulose; Microradiography; Minerals; Temperature; Time Factors; Tooth Demineralization; Tooth Remineralization

The steady-state shear and linear viscoelastic deformations of semidilute suspensions of rod-shaped nanocrystalline cellulose (NCC) particles in 1.0% hydroxyethyl cellulose and carboxymethyl cellulose solutions were investigated. Addition of NCC at the onset of semidilute suspension concentration significantly altered the rheological and linear viscoelastic properties of semidilute polymer solutions. The low-shear viscosity values of polymers solutions were increased 20-490 times (depending on polymer molecular weight and functional groups) by the presence of NCC. NCC suspensions in polymer solutions exhibited yield stresses up to 7.12 Pa. Viscoelasticity measurements also showed that NCC suspended polymer solutions had higher linear elastic moduli than the loss moduli. All of those results revealed the gel formation of NCC particles and presence of internal structures. The formation of a weak gel structure was due to the nonadsorbing macromolecules which caused the depletion-induced interaction among NCC particles. A simple interaction energy model was used to show successfully the flocculation of NCC particles in the presence of nonadsorbing polymers. The model is based on the incorporation of the depletion interaction term between two parallel plates into the DLVO theory for cubic prismatic rod shaped NCC particles.

Topics: Carboxymethylcellulose Sodium; Cellulose; Colloids; Elasticity; Nanoparticles; Solutions; Viscosity; Water

The aim of this study was to develop an optimal gastroretentive drug delivery system (GRDDS) for administering Losartan. Additionally, the influence of optimized GRDDS on the bioavailability of Losartan and the formation extent of active metabolite E3174 by CYP2C9 polymorphism was investigated. Swellable and floatable GRDDS tablets combining hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (NaCMC), and sodium bicarbonate were prepared at various compression pressures for evaluating swelling characteristics and floating capacity. Then Losartan was incorporated into optimized formulations for in vitro and in vivo characterizations. An appropriate ratio of HEC to NaCMC, addition of sodium bicarbonate, and compression at lower pressures resulted in the tablets floating over SGF for more than 16 h and swelling to 2 cm in diameter within 3h. The release patterns of Losartan from these tablets were pH-dependent. Results of the clinical trials showed that the mean bioavailability from GRD-A (HEC 91.67%, sodium bicarbonate 3.33% and Losartan 8.33%) was approximately 164%, relative to the immediate-release product (Cozaar). MRT and t(max) values were greater and C(max) values were lower for the GRDDS tablets compared with Cozaa. The lower bioavailability of Losartan in the CYP2C9*1/*1 subjects than CYP2C9*1/*3 subjects was found and could be due to the variety of enzymatic activity.

Topics: Angiotensin II Type 1 Receptor Blockers; Aryl Hydrocarbon Hydroxylases; Carboxymethylcellulose Sodium; Cellulose; Chemistry, Pharmaceutical; Cytochrome P-450 CYP2C9; Drug Compounding; Drug Delivery Systems; Humans; Losartan; Polymorphism, Genetic; Sodium Bicarbonate; Solubility; Tablets

In this study the formulation and rheological characterisation of novel candidate ophthalmic viscosurgical devices (OVD) based on binary interactive polymer gels is described. Primary systems containing either hydroxyethylcellulose (HEC) or sodium carboxymethylcellulose (NaCMC) or binary interactive gels composed of HEC and NaCMC were manufactured. Rheological characterisation was performed using texture profile analysis and oscillatory rheometry. All formulations exhibited pseudoplastic flow. Systems composed of HEC or HEC and NaCMC behaved as gels (G' > G") over the range of oscillatory frequencies whereas systems composed of NaCMC were primarily elastoviscous. Increasing the polymer concentration in all systems increased the compressional rheological properties (hardness, compressibility), zero frequency viscosity (derived from the Cross model) and the viscoelastic properties (G', G" and eta'). Rheological synergy was observed in the binary gels and was indicative of interaction between the parent polymers. Importantly, the range of rheological properties offered by the binary mixtures was greater than those exhibited by the primary systems. The binary systems described in this study possessed viscoelastic properties and steady-state viscosities that were similar to commercially available systems and would therefore be appropriate for the maintenance of the ocular space. The acceptable compressional rheological and pseudoplastic properties of these systems would facilitate administration into the eye using a syringe. Additionally and uniquely, the excellent adhesive properties of the binary interactive gels would suggest an ability to interact with the corneal endothelium that would offer protection during phacoemulsification. Based on the described rheological properties it is suggested that binary gels composed of mass ratios of HEC to NaCMC of either 3.6: 2.4 or 2.4: 3.6 would be acceptable as OVD and would uniquely offer duality of function.

Topics: Adhesiveness; Carboxymethylcellulose Sodium; Cellulose; Compressive Strength; Cornea; Corneal Injuries; Elasticity; Endothelium; Gels; Hardness; Humans; Intraoperative Complications; Lens Implantation, Intraocular; Phacoemulsification; Polymers; Rheology; Viscosity

Mucoadhesive patches containing 10mg miconazole nitrate were evaluated. The patches were prepared with ionic polymers, sodium carboxymethyl cellulose (SCMC) and chitosan, or non-ionic polymers, polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC) and hydroxypropylmethyl cellulose (HPMC). Convenient bioadhesion, acceptable elasticity, swelling and surface pH were obtained. Patches exhibited sustained release over more than 5h and the addition of polyvinyl pyrrolidone (PVP) generally enhanced the release rate. Optimum release behaviour was shown with patches containing 10% w/v PVA and 5% w/v PVP. Study of the in vivo release from this formulation revealed uniform and effective salivary levels with adequate comfort and compliance during at least 6h. On the contrary, in vivo release of the commercial oral gel product resulted in a burst and transient release of miconazole, which diminished sharply after the first hour of application. Storage of these patches for 6 months did not affect the elastic properties, however, enhanced release rates were observed due to marked changes in the crystal habit of the drug.

Topics: Adhesiveness; Adjuvants, Pharmaceutic; Administration, Buccal; Administration, Oral; Adult; Antifungal Agents; Carboxymethylcellulose Sodium; Cellulose; Chemistry, Pharmaceutical; Chitin; Chitosan; Cross-Over Studies; Delayed-Action Preparations; Drug Stability; Female; Humans; Hypromellose Derivatives; In Vitro Techniques; Male; Methylcellulose; Miconazole; Middle Aged; Mouth Mucosa; Polyvinyl Alcohol; Time Factors

The effects of polymers applicable in saliva substitutes on the anti-Candida activity of the cationic antimicrobial peptide dhvar1 were investigated. Dhvar1 is a derivative of the 14 C-terminal amino acids of histatin 5. The effects of the following polymers were tested: uncharged hydroxyethylcellulose (HEC), negatively charged xanthan (XG) and three types of negatively charged carboxymethylcellulose (CMC) of identical mass but different degrees of carboxylic acid-group substitution (DS). The effects were tested at pH 4.0, 7.0 and 8.5 in a killing assay. HEC had no effect at any pH tested; XG and the three types of CMC caused a decrease in activity at increasing concentrations. Within the CMC group, inhibition increased slightly with increasing DS. These results suggest that the reduction in activity associated with these polymers is the result of electrostatic interaction between the positively charged peptides and the negatively charged polymers. In the absence of polymers, no effect of pH was found on the activity of dhvar1. In the presence of the charged polymers XG and CMC, lowering the pH from 7.0 to 4.0 resulted in a decrease of dhvar1 activity. It was concluded that, with respect to the retention of activity, HEC is the most appropriate polymer for use in combination with dhvar1. However, for use in saliva substitutes XG seems more suitable because of its rheological properties. If XG or CMC are to be used, their reductive effect on the anti-Candida activity of dhvar1 should be compensated for by increasing the peptide dose.

Topics: Antifungal Agents; Antimicrobial Cationic Peptides; Candida albicans; Carbohydrates; Carboxymethylcellulose Sodium; Cellulose; Dose-Response Relationship, Drug; Drug Interactions; Histatins; Humans; Microbial Sensitivity Tests; Peptide Fragments; Polymers; Polysaccharides; Polysaccharides, Bacterial; Rheology; Saliva, Artificial; Salivary Proteins and Peptides; Viscosity

A number of polymers which have previously been tested for their applicability as thickening agents in saliva substitutes were studied in vitro for their caries-protective properties. These were: polyacrylic acid, carboxymethylcellulose, xanthan gum, guar gum, hydroxyethylcellulose and porcine gastric mucin. The polymers were tested for their effects on: (1) growth of hydroxyapatite crystals in a supersaturated calcium phosphate solution, (2) dissolution of hydroxyapatite crystals in 50 mM acetic acid, pH 5.2 and (3) demineralization and remineralization of bovine enamel in a pH-cycling model. Growth of hydroxyapatite crystals was strongly inhibited by polyacrylic acid and carboxymethylcellulose at very low concentrations (0.005% w/v). Other polymers displayed lower inhibition of hydroxyapatite crystal growth. Hydroxyapatite dissolution was inhibited by all polymers except by hydroxymethylcellulose and xanthan gum. This occurred both in the presence of the polymers as well as after a 30-min preincubation. In the pH-cycling experiment, bovine enamel specimens with preformed lesions were alternately exposed to a demineralization buffer and a remineralization buffer containing the polymers hydroxyethylcellulose, carboxymethylcellulose, xanthan gum, polyacrylic acid, or porcine gastric mucin. A remineralization buffer containing 1 ppm NaF was used as a positive control. Under the experimental conditions, the control experiment without additives resulted in a net mineral loss (30.6 mumol Ca/cm2 after 14 days of pH cycling). In the presence of 1 ppm NaF, a small mineral gain was observed (8.6 mumol/cm2). All polymers largely inhibited further demineralization (1.2-12.3 mumol/cm2) except polyacrylic acid which, inhibited of its high calcium-binding capacity, caused demineralization, especially in the remineralization buffer (17.1 mumol/cm2). In conclusion, polymers tested in this study, except the polyacrylic acid, reduced the demineralization of enamel in vitro. The precise mechanism of the protective effect is not clear but it is speculated that formation of an absorbed polymer layer on the hydroxyapatite or enamel surface may provide protection against acidic attacks.

Topics: Acetic Acid; Acrylic Resins; Adsorption; Animals; Buffers; Calcium Phosphates; Carboxymethylcellulose Sodium; Cariostatic Agents; Cattle; Cellulose; Crystallization; Dental Enamel; Dental Enamel Solubility; Durapatite; Galactans; Humans; Hydrogen-Ion Concentration; Mannans; Mucins; Plant Gums; Polymers; Polysaccharides, Bacterial; Saliva, Artificial; Sodium Fluoride; Solubility; Swine; Tooth Demineralization; Tooth Remineralization