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Spinal cord injury can lead to severe dysfunction as a result of limited nerve regeneration that is due to an inhibitory environment created at the site of injury. Neural tissue engineering using materials that closely mimic the extracellular matrix (ECM) during neural development could enhance neural regeneration. Glycosaminoglycans (GAGs), which are sulfated polysaccharides, have been shown to modulate axonal outgrowth in neural tissue depending upon the position and degree of sulfation. Cellulose sulfate (CelS), which is a GAG mimetic, was evaluated for its use in promoting neurite extension. Aligned fibrous scaffolds containing gelatin blended with 0.25% partially sulfated cellulose sulfate (pCelS), having sulfate predominantly at the 6-carbon position of the glucose monomer unit, and fully sulfated cellulose sulfate (fCelS), which is sulfated at the 2-, 3-, and 6-carbon positions of the glucose monomer unit, were fabricated using the electrospinning method. Comparisons were made with scaffolds containing native GAGs, chondroitin sulfate-A (CS-A) and chondroitin sulfate-C (CS-C), which were obtained from commercial sources. CS-A and CS-C are present in neural tissue ECM. The degree of sulfation and position of sulfate groups was determined using elemental analysis, Fourier-transform infrared spectroscopy (FTIR), Raman microspectroscopy, and 13C nuclear magnetic resonance (NMR). In vitro studies examined both nerve growth factor (NGF) binding on scaffolds and neurite extension by dorsal root ganglion (DRG) neurons. NGF binding was highest on scaffolds containing pCelS and fCelS. Neurite extension was greatest for scaffolds containing fCelS followed by pCelS, with the lowest outgrowth on the CS-A containing scaffolds, suggesting that the degree and position of sulfation of CelS was permissible for neurite outgrowth. This study demonstrated that cellulose sulfate, as a GAG mimetic, could be used for future neural tissue regeneration application. Scaffolds that closely mimic the native extracellular matrix (ECM) during development may be a promising approach to enhance neural regeneration. Here, we reported a glycosaminoglycan (GAG) mimetic derived from cellulose that promotes neurite extension over native GAGs, chondroitin sulfate-A (CS-A) and chondroitin sulfate-C (CS-C), which are present in neural ECM. Depending upon the degree and position of sulfation, the GAG mimetic can impact nerve growth factor binding and permissive neurite outgrowth. [ABSTRACT FROM AUTHOR]

Flocculants are widely used along with coagulant to increase the efficiency of coagulation-flocculation process for removal of colloidal particles from wastewaters. The most widely used flocculants are synthetic which have some problems such as non-biodegradability and release of toxic residual monomers. The main aim of this study is to evaluate the performance of cellulose sulfate (CS), which was synthesized through sulfonation of cotton, as a biodegradable and natural-based flocculant. Reaction time as an important factor in the sulfonation reaction was optimized for obtaining CS with high charge density and suitable fiber size. The sulfate content, charge density (CD) and morphology of each CS were determined to investigate and select the best CS for the flocculation process. A suspension containing kaolin clay was used as a colloidal test solution and coagulation was performed using alum (as a coagulant) and CS (as a flocculant). Optimization was performed using response surface methodology (RSM). The optimization results showed that CS had a good performance in turbidity reduction in coagulation-flocculation treatment and maximum turbidity reduction (98.9%) was obtained at alum dosage of 23.1 mg/L, CS dosage of 7.2 mg/L and pH 6.2. The results showed that the pH variation had insignificant effect on the CS dosage. Zeta potential measurements and microscopic photos of flocs confirm charge neutralization and bridge formation in flocculation using cellulose sulfate, respectively. Also, the total chemical consumption reduced compared with the use of alum alone. As a consequence, CS can be considered as a suitable alternative for conventional flocculants. [ABSTRACT FROM AUTHOR]

We have investigated the proton conductivity, solvent uptake, and the methanol permeability coefficient (PM) in aqueous methanol solutions of the cellulose sulfate (CS) electrolyte membranes which were prepared by sulfating regenerated cellulose membranes. The proton conductivity of the CS membranes is enhanced with increasing number of sulfate groups. Solvent uptake and PM for the CS membranes are almost independent of methanol content, and the CS membranes with higher solvent uptake show higher PM. The introduction of cross-linkage into the CS membranes not only enhances the proton conductivity but also decreases the methanol permeability because of a considerable reduction in solvent uptake. The cross-linked CS membranes exhibit a proton conductivity of 0.081 S cm-1 at room temperature, which is comparable to that of Nation 112®. The methanol permeability measured by using a 3 M methanol solution is less than half, compared with Nation 112®. [ABSTRACT FROM AUTHOR]

We have investigated the proton conductivity, solvent uptake, and the methanol permeability coefficient (PM) in aqueous methanol solutions of the cellulose sulfate (CS) electrolyte membranes which were prepared by sulfating regenerated cellulose membranes. The proton conductivity of the CS membranes is enhanced with increasing number of sulfate groups. Solvent uptake and PM for the CS membranes are almost independent of methanol content, and the CS membranes with higher solvent uptake show higher PM. The introduction of cross-linkage into the CS membranes not only enhances the proton conductivity but also decreases the methanol permeability because of a considerable reduction in solvent uptake. The cross-linked CS membranes exhibit a proton conductivity of 0.081 S cm-1 at room temperature, which is comparable to that of Nation 112®. The methanol permeability measured by using a 3 M methanol solution is less than half, compared with Nation 112®. [ABSTRACT FROM AUTHOR]