Cellulose Matrices Research Articles

Solid-phase spectrophotometric analysis of natural water with the simultaneous sample preparation and dynamic preconcentration of test components on reagent cellulose matrices

A photocolorimeter was developed; this instrument made it possible to perform sample preparation, to preconcentrate test water components on indicator cellulose matrices, and to simultaneously measure their light absorption. A white light-emitting diode and a Digital color sensor S9706 photodiode, which simultaneously detected red (615 nm), green (540 nm), and blue (465 nm) regions of the spectrum, were used in the instrument. The applicability of the photocolorimeter to the determination of 36 components and characteristics of water was demonstrated. The photocolorimeter was proposed for the simultaneous determination of 20 components at a level of their maximum permissible concentrations for fishery water (RSD < 10%) for 10–15 min.

Monte Carlo simulation for an assessment of standard validity and quantitative X-ray microanalysis in plants

Protein matrices with known concentration of elements are used as standards in X-ray microanalysis of biological materials. The aim of the study was to assess if protein standards (gelatine) could be applied for quantitative X-ray microanalysis of carbohydrate material (cellulose) of plant cell walls by means of Monte Carlo simulations. Plant roots grown in 133Cs contaminated soil and gelatine with known elemental concentration were prepared according to freeze-drying protocols. The atomic fractions of gelatine and cellulose were used to simulate spectra and than compared to experimental ones. There was a good agreement in bremsstrahlung generation between gelatine and cellulose matrices. The experimental and simulated spectra of gelatine revealed a difference in background shape at low energies but corrected if specimen was tilted to -10° or the matrix density increased to 0.95 g/cm3. Minimum detection limit (MDL) simulated for 133Cs La in cellulose was also in agreement with that experimentally calculated for gelatine standard. Protein standard resembles carbohydrate materials and can be used for quantitative analysis of plant cell walls. However, using Monte Carlo simulations to predict analytical conditions for biological materials and elemental MDL, differences in topography and/or gelatine densities should be taken into consideration.

Surface-sensitive method to determine calcium carbonate filler contents in cellulose matrices

This paper describes a method using attenuated total reflectance infra-red spectroscopy to determine the surface concentration of calcium carbonate in paper samples, by applying the linear relationship between the relative infra-red absorption integrals and the concentration. The method was able to detect micro-variations in the surface concentration and could also distinguish between different sheets as well as between the top and bottom side of one sheet. The samples were also split and the calcium carbonate concentration was determined within and compared to bulk calcium carbonate concentration determined from ash testing. The surface results were also compared with analysed scanning electron microscopy images generated from back-scattering electrons. The comparison shows that both sets of results are in excellent agreement. Depending on the sample, large errors (95% confidence) were observed. These, however, are caused by micro-variations of the surface concentration, rather than by inaccuracies of the technique, which is estimated to be less than 1%. Furthermore, measurements of various sample orientations suggest that anisotropic polarisation effects can be neglected. The method can be applied to paper and cellulose matrices having calcium carbonate filler contents of less than 50%. Due to spectral overlaps it is not suitable to determine kaolin filler contents.

Solid-phase fluorescence in chemical test methods of analysis based on the principles of planar chromatography

Morin immobilized on cellulose matrices was used as a reagent for determining Al, Be, and Zr(IV) by the length of the fluorescent zone on a test strip after its contact with the test solution and by the fluorescence intensity of the reaction zone of the indicator matrix after passing the test solution through it. A test procedure was developed for determining 0.2–200 mg/L Al in potable water using paper test strips sealed in a polymer film. Test procedures were developed for determining 0.0001–1 mg/L Al and 0.00001–0.1 mg/L Be in river water by the intensity of the fluorescent zone on the indicator viscose fabric after passing 100 mL of the test solution through it, using a test facility. The time of analysis was 15–20 min. The relative standard deviation did not exceed 40% in the former case and 60% in the latter case.

A novelin vitroflat-bed perfusion biofilm model for determining the potential antimicrobial efficacy of topical wound treatments

To develop an in vitro flat-bed perfusion biofilm model that could be used to determine the antimicrobial efficacy of topically applied treatments. Pseudomonas aeruginosa and Staphylococcus aureus biofilms were grown within continuously perfused cellulose matrices. Enumeration of the biofilm density and eluate was performed at various sampling times, enabling determination of the biofilm growth rate. Two antimicrobial wound dressings were applied to the surface of mature biofilms and periodically sampled. To enable real-time imaging of biofilm growth and potential antimicrobial kinetics, a bioluminescent Ps. aeruginosa biofilm was monitored using low-light photometry. Target species produced reproducible steady-state biofilms at a density of c. 10(7) per biofilm support matrix, after 24-h perfusion. Test dressings elicited significant antimicrobial effects, producing differing kill kinetic profiles. There was a good correlation between photon and viable count data. The model enables determination of the antimicrobial profile of topically applied treatments against target species biofilms, accurately differentiating bactericidal from bacteriostatic effects. Moreover, these effects could be monitored in real time using bioluminescence. This is the first in vitro biofilm model which can assess the antimicrobial potential of topical therapies in a dynamic growth environment.

Strongly fluorescent hydrogels with quantum dots embedded in cellulose matrices

Hydrogels having strong fluorescence were fabricated successfully, for the first time, from cellulose and quantum dots (QDs) in a NaOH/urea aqueous system via a mild chemical cross-linking process. The CdSe/ZnS nanoparticles were embedded firmly in the cellulose matrices, as a result of strong interactions between the CdSe/ZnS nanoparticles and cellulose after hydrolysis of the QDs ligands. The results from FTIR spectra, transmission electron microscopy, scanning electron microscopy and photoluminescence (PL) spectra revealed that the cellulose networks in the hydrogels played an important role in the protection of the CdSe/ZnS structure and preservation of the quantum dots characteristics. The cellulose–QDs hydrogels exhibited strong PL emission and nearly pure color from green to red, depending on the size of the QDs. Moreover, the hybrid hydrogels possessed a good transparence and compressive strength. This work provides a new pathway for the construction of safe and biocompatible biopolymer–QDs hydrogels with a high efficiency of PL emission.

2,3,7-Trihydroxyfluorones immobilized on cellulose matrices in test methods for determining rare elements

It was shown that 2,3,7-trihydroxyfluorones immobilized by adsorption on cellulose matrices can be used as reagents for the test determination of Mo(VI), Ti(IV), Ge(IV), Hf(IV), Nb(V), Ta(V), W(VI), Bi(III), V(IV), and Zr(IV). The change of the protolytic and complexing properties of trihydroxyfluorones immobilized on cellulose matrices was considered in comparison to corresponding properties in a solution. It was found that the reactions of trihydroxyfluorones with rare elements on cellulose matrices and in a solution exhibit similar effects upon the addition of cetylpyridinium. These effects are the bathochromic shift of the absorption maxima of the reagents and their complexes with analytes and the extension of the range of optimum acidity for complex formation. The complexation of salicylfluorones with the titanium(IV) in solution and on cellulose paper was studied by IR spectrometry. Phenylfluorone immobilized on a mixed-fiber cloth as used in test determinations of (mg/L) 0.05–5 Ti(IV), V(IV), Hf(IV), Nb(V), and Mo(VI); 0.01–5 Ge(IV) and Zr(IV); 0.05–1 Bi(III) and W(VI); and 0.1–5 Ta(V) by the color intensity of the indicator matrix after passing through 20 mL of a test solution. It was shown that phenylfluorone immobilized on cellulose paper can be used to determine (mg/L) 0.05–50 Ti(IV), 0.5–1000 Ge(IV), 0.5–500 Zr(IV), 5–200 Bi(III), 0.1–50 Mo(VI), 0.1–1000 V(IV), 0.1–100 Nb(V), 0.1–800 Hf(IV), 1–100 Ta(V), and 1–800 W(VI) by the length of the colored zone of a test strip after it was brought into contact with a test solution.

Molecular modeling of interfaces between cellulose crystals and surrounding molecules: Effects of caprolactone surface grafting

A technical problem in cellulosic nanocomposite materials is the weak interaction between hydrophilic cellulose and hydrophobic polymer matrices. One approach to solve this difficulty is to chemically graft monomers of the matrix polymer onto the cellulose surface. An important question is to understand the effect such surface modification has on the interfacial properties. Semi-empirical approaches to estimate work of adhesion based on surface energies do not provide information on specific molecular interactions. Details about these interactions were obtained using molecular dynamics (MD) simulation. Cellulose interfaces with water and caprolactone medium were modeled with different amounts of grafted caprolactone. The modification lead to an increased work of adhesion between the surface and its surrounding medium. Furthermore, the MD simulations showed that the interaction between cellulose, both modified and non-modified, and surrounding medium is dominated by Coulomb interactions, predominantly as hydrogen bonds.

Features of test reactions of metal ions with Chromazurol S immobilized on thin-layer matrices

Features of the reactivity of Chromazurol S immobilized on paper, clothes of natural and artificial cellulose fibers, silk, and nylon were studied. A weak retention of Chromazurol S on cellulose matrices and nylon (retention is 10–60%) and high retention on silk (>70%) were found. Upon the adsorption of the reagent on solid matrices, a bathochromic shift of absorption bands is observed in comparison with its absorption in solutions. The analysis of sorption isotherms and IR spectra suggested that the reagent can be fixed on the matrix by hydrogen bonds, electrostatic forces, and hydrophobic interactions. An increased ability of the complexes of metal ions with Chromazurol S to adsorb on the matrices was noted; a significant (100–130 nm) bathochromic shift of the absorption bands in comparison with the absorption of the complexes in aqueous solutions is observed in this case, and the number of ligands coordinated by the metal ion also increases. Based on the study of the sorption isotherms and absorption spectra in the visible and IR regions for complexes, the assumption of the hydrophobic hydration of the resulting complexes in the intermicellar space of the matrix was suggested. Test reactions of Chromazurol S immobilized on paper, viscose, and silk with Al, Be, Fe(III), Zr(IV), and Cr(III) ions were studied.

Test determination of titanium(IV) and germanium(IV) in waste and natural waters in the presence of each other

It was demonstrated that trihydroxyfluorones immobilized on cellulose matrices can be used as the reagents for the rapid determination of titanium(IV) and germanium(IV). A high retention of trihydroxyfluorones on cellulose paper (78–98%) and strong chemically stable mixed fabric (74–97%) makes it possible to use these materials for the immobilization of the reagents. Mixed fabric (viscose with cotton) with immobilized phenylfluorone was used for the test determination of 0.05–5 mg/L titanium(IV) and 0.01–5 mg/L germanium( IV) by the color intensity of the reaction zone of the indicator matrix after passing 20 mL of the analyzed solution through it. A test procedure was developed for the determination of 1–200 mg/L titanium(IV) and 0.5–1000 mg/L germanium(IV) by the length of the colored zones of the test strips sealed in a polymer film. The time of the analysis is 10–15 min. The relative standard deviation of the results of the determination of germanium( IV) and titanium(IV) is no higher than 30%.

Application of heparinized cellulose affinity membranes in recombinant adeno-associated virus serotype 2 binding and delivery

The microporous affinity membrane based on cellulose matrices offers minimal mass-transfer effects in membrane chromatography with low nonspecific adsorption. In this research, we tested a novel application of the microporous, heparinized cellulose membranes for their affinity toward recombinant adeno-associated virus serotype 2 (rAAV2, which uses heparan sulfate proteoglycans as the primary cellular receptor) to develop a controlled, substrate-mediated viral vector delivery. We conjugated rAAV2 to an epoxy-crosslinked heparin cellulose membrane, which led to vector transduction upon cellular adhesion. When adhered, human fibroblasts exhibited proliferation kinetics similar to those on the standard polystyrene tissue-culture surface. Using fluorescent proteins as the reporter, we showed that the heparin-bound rAAV2 particles remained active and that the rAAV2-heparin binding was reversible and capable of mediating transgene delivery in cell culture. In addition, we applied the affinity membrane to adsorb unpurified rAAV2 from the crude lysate of packaging cells via the ligand–receptor binding, avoiding the use of conventional ultracentrifugation or chromatography in preparation of infectious rAAV2 for transduction. Our work explores a new application of affinity cellulose membranes in substrate-mediated viral vector delivery, which can be a useful tool in developing protocols for localized gene transfer.

Parallel Processing of Microwave-Assisted Organic Transformations

Microwave-assisted organic synthesis is an enabling technology that has been exploited for a variety of applications including medicinal chemistry/drug discovery projects where speed is often a critical factor. In this review, applications of microwave-assisted organic synthesis employing a parallel processing regime are summarized. Examples include parallel synthesis in domestic microwave ovens, the use of specialized multivessel rotors and microtiter plates in dedicated multimode microwave reactors, and applications of SPOT synthesis on cellulose matrices.

Emission of Thioflavin T and its Off-On Control in Polymer Membranes‡¶

The absorption and emission spectral properties of thioflavin T (TFT+) in Nafion (Nf) and cellulose matrices have been studied. Formation of the emittive dimer is observed in both matrices. The monomer TFT+ emission is blueshifted in Nafion membrane (Nf), whereas it is redshifted in cellulose membrane when compared with the emission in aqueous solution. The dimer emission of TFT+ in the Na+-Nf membrane undergoes off–on switching with acids and alkalis. The TFT+ molecule undergoes protonation in the H+-Nf and the protonated dye is fluorescent. The dimer emission of TFT+ is not observed in the dry H+-Nf membrane because of the protonation of the TFT+ molecule. The diffusion coefficient and the free energy of hydrophobic interaction for the TFT+ molecule in the Nf membrane are calculated. The TFT+ molecule experiences hydrophobic and electrostatic interactions in the Nf matrix, whereas it experiences a polar environment in the cellulose membrane. The 3D emission spectral studies support the formation of the emittive dimer in both Nf and cellulose matrices.

Test determination of aluminum, beryllium, and cationic surfactants using phenolcarboxylic acids of the triphenylmethane series immobilized on cloths from synthetic and natural fibers

We consider the use of cloth matrices from viscose and cotton fibers bearing phenolcarboxylic acids of the triphenylmethane series immobilized by adsorption in chemical test methods of analysis. Chrome Azurol S, Sulfochrome, and Eriochrome Cyanine R were used for immobilization. It was found that the reagents are weakly retained on cellulose matrices. The degree of retention varied from 10 to 60%. It was observed that the reagent complexes of metal ions exhibited enhanced adsorbability on the matrices. Cloths with immobilized Chrome Azurol S were used in the test determination of 0.0005–0.5 mg/L beryllium and 0.0005–1.0 mg/L aluminum. When the reaction products were preconcentrated on the cloth from 100 mL of a test solution, the detection limit was 0.0001 mg/L. Procedures were developed for determining 0.1–100 mg/L aluminum and 0.02–0.6 mg/L beryllium in solutions using cloth test strips encapsulated into a polymeric film. It was demonstrated that Sulfochrome and Eriochrome Cyanine R immobilized on cloths can be used to determine 0.01–1 and 1–1000 mg/L cationic surfactants.

Selective Removal of DNA from Bioproducts by Polycation‐Immobilized Cellulose Beads

This paper describes a method for the selective removal of DNA from various cellular products using columns packed with polycation‐immobilized cellulose beads. Polyethyleneimine (PEI), poly‐N,N‐dimethylaminopropylacrylamide (poly(DAPA)) and poly(ϵ‐lysine) (PϵL), all of which have cationic properties, were used as the ligands on the beads. Cellufine‐GC15® and ‐CPC® were used as cellulose matrices. Adsorption of DNA by the beads was determined using a batchwise method or a column method. Each bead type showed high DNA adsorbing activity at pH 7.0 and ionic strengths of μ=0.05–0.8. The larger the pore size of the beads, the larger the DNA‐adsorbing activity. The DNA adsorbing capacities per wet mL of PEI‐, poly(DAPA)‐ and PϵL immobilized Cellufine‐CPC with large pore sizes, were 3.7, 3.2, and 1.8 mg, respectively. When a protein, such as bovine serum albumin (BSA) or γ‐globulin, was present in solution with the DNA under physiological conditions (pH 7.0, μ=0.2), the DNA selectivity of the PEI immobilized Cellufine‐CPC columns was unsatisfactory, because both the DNA and the protein were adsorbed into the column. In contrast, the poly(DAPA) immobilized Cellufine‐CPC column selectively removed DNA from each protein solution contaminated with DNA under similar conditions: the DNA concentration in each treated protein solution was below 10 ng mL−1, and high recovery of each protein (>92%) was obtained.

Spatially resolved solvent interaction with glassy HPMC polymers studied by magnetic resonance microscopy

Magnetic resonance microscopy was used to study the interaction of an alkaline water solvent (pH=12) with hydroxypropylmethyl cellulose (HPMC) matrices with different molecular masses M w = 12 000 , 86 000, and 120 000. The polymers in the form of cylinders were hydrated at 37 °C and monitored at equal time intervals with a 300 MHz Bruker AVANCE. The spatially resolved spin–spin relaxations times T 2 and diffusion coefficients D of the solvent molecules within the gel layer of HPMC samples, along with changes in the dimension of the glass core of the polymers were determined as a function of hydration times. The experimental data allows us to characterize the diffusion mechanism as being Fickian and to determine the mean diffusivity values D ¯ of the solvent molecules for each voxel within the gel of the studied polymers. The influence of the molecular mass of the HPMC polymers on swelling properties has been shown.

Sorption of nicotine to cellulose powders.

The purpose of this study was to investigate the influence of the crystallinity, surface area, and pore volume of cellulose powders on the loading, release, and stability of nicotine. Four different types of cellulose powders with varying crystallinity index, surface area, and pore volume were produced and characterized. The powders were loaded with nicotine by rotary evaporation from an ethanol solution and by adsorption from nicotine-saturated air. The release of nicotine from loaded cellulose powders into both a passing airstream and water was investigated by UV spectroscopy. A 3-month stability study was conducted and the total sum of nicotine oxidation products was measured. Nicotine loading and release were independent of cellulose powder crystallinity, whereas it was possible to load more nicotine on the cellulose powder with a large surface area and pore volume. Release into water was very rapid and almost complete for all samples. Nicotine was most stable when loaded on the powder with a large surface area and pore volume. Highly porous cellulose matrices could be useful for stabilization and handling of both nicotine and other liquid active pharmaceutical ingredients.

Sustained release of acetaminophen from a heterogeneous mixture of two hydrophilic non-ionic cellulose ether polymers

This study examined the release of acetaminophen (APAP) from hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) matrices. The effect of pseudoephedrine (PE) as a co-active, HPMC:HPC ratio, polymer loading, pH of the dissolution media, and compression force on APAP release were studied. Granules formulated with APAP or both APAP and PE, and various blends of HPMC and HPC were compressed into tablets at different compression forces. APAP release from the matrix tablets was not considerably influenced by changes in HPMC:HPC ratio or compression force. The rate of drug release was significantly affected by pH of the dissolution media, total polymer loading, and the presence of PE. Drug release from the formulations containing both APAP and PE was slower than those containing only APAP. Drug release from tablets formulated with APAP only showed an initial burst at pH 1.16 or 7.45. Formulations containing both APAP and PE showed slower drug release at pH 1.16 than at pH 7.4. The drug release data showed a good fit to the Power Law Model. The mechanism of drug release is consistent with a complex behavior. The results of the tablet erosion studies indicated that the amount of APAP released was linearly related to the percentage of tablet weight loss. The kinetics of tablet water uptake was consistent with a diffusion and stress relaxation mechanism.

Formulation Development and Human In Vitro‐In Vivo Correlation for a Novel, Monolithic Controlled‐Release Matrix System of High Load and Highly Water‐Soluble Drug Niacin

Novel, controlled‐release formulations for high drug load, highly water soluble compound niacin based on polyethylene oxide (PEO) and hydroxypropylmethyl cellulose (HPMC) matrices were developed and investigated. The effect of sodium bicarbonate as a modulator of swelling, erosion, and drug release and its impact on changes in the kinetics of axial swelling and gel strength were evaluated by textural analysis during dissolution study. The drug release rate from PEO‐based matrices was faster and correlated with lower gel strength, greater water uptake, and greater matrix erosion. Slower release rate and greater release duration correlated significantly with greater matrix swelling with negligible matrix erosion for the HPMC‐based matrix system. Inclusion of sodium bicarbonate in the polymeric matrix salted out the macromolecules and increased gel strength and gel viscosity, especially in the vicinity of the swelling fronts. An in vivo study in human subjects after administration of the formulations and a commercial product exhibited similar plasma concentrations. For the formulation of interest, the mean drug fraction absorbed by the body was calculated by the Wagner‐Nelson technique, and a level A “in vitro‐in vivo correlation” was observed between the percent released in vitro and percent absorbed in vivo. The developed formulations appear to be robust and easy to manufacture with maximum flexibility with respect to drug dose, polymeric carriers, duration, and kinetics of drug release.

The swelling properties of hydroxypropyl methyl cellulose loaded with tetracycline hydrochloride: magnetic resonance imaging study

Magnetic resonance imaging was used to study the behavior of the gel layer thickness in hydroxypropyl methyl cellulose (HPMC) matrices loaded with different amounts of soluble tetracycline hydrochloride. The time dependence of the diffusion front, effective T 2, and proton-density analysis clearly indicates a Case II diffusion mechanism in the system composed of water solution of hydrochloric acid (pH=2) and HPMC. The solvent penetration front was used to describe the swelling properties as well as the integrity of the HPMC matrices. The results show that the tetracycline hydrochloride decreases the resistance of the HPMC network structure against the movement of solvent molecules. On the other hand the swelling properties of the matrix increase with the amount of drug in the matrix.