Quaternized Cellulose Research Articles

Antifungal activity and humidity sensitivity of quaternized cellulose synthesized in NaOH/urea aqueous solution

In this work we report the fabrication of cellulose-based humidity responsive material with antifungal activity. The quaternized cellulose (QC) derivatives with low degree of substitution (DS) values of 0.08–0.37 were synthesized in NaOH/urea aqueous solution. Water insoluble QC membranes (c-QCM) were prepared by casting from QC aqueous solutions, followed by crosslinking with glutaraldehyde. The c-QCMs were disintegrated in acid solutions, but were able to keep membrane shape in neutral and mild basic solutions with pH value of 7.2 and 9.7. The equilibrium water adsorption ratios of c-QCMs were in the range of 66–98%, depending on the DS values of quaternary ammonium groups and the pH value of the aqueous solutions. The antifungal activity of QC was evaluated and found that QC could effectively inhibit the reproduction of Rhizopus stolonifer, Aspergillus flavus and Penicillium digitatum, with minimum inhibitory concentration of 5, 10, and 7.5 mg/mL, respectively. The resistivity of the c-QCM changed for about 65–134 times corresponding to the change of environmental relative humidity from 20 to 99%; and the performance of c-QCM as a resistive-type humidity responsive material was consistent in the cycling of relative humidity.

Swelling Behaviors of pH- and Salt-Responsive Cellulose-Based Hydrogels

Ampholytic hydrogels with pH and salt responsive properties have been synthesized by cross-linking quaternized cellulose (QC) and carboxymethyl cellulose (CMC) with epichlorohydrin (ECH) in NaOH aqueous solution. The swelling behaviors of the QC/CMC hydrogels were studied as a function of the polymer composition, pH, and salt concentration. The equilibrium swelling ratio of the hydrogel in ultrapure water strongly depended on the composition, and increased dramatically from 8.6 to 498 g/g with the change of the weight ratio of QC to CMC from 3:1 to 1:3 (w/w). The hydrogel (Gel32) consisted of QC and CMC in the ratio of 3:2 (w/w) had the minimum swelling ratio, and it was electrically neutral. The results from ζ-potential experiments were in good agreement with the theoretically calculated stoichiometry for balanced charge, confirming that the weight ratio of QC and CMC was 1.5, corresponding to Gel32. Furthermore, all hydrogels exhibited excellent pH sensitivity in the range of pH from 1 to 13 and shrunk significantly at pH 12 on the whole. The hydrogels displayed smart swelling behaviors in NaCl, CaCl2, and FeCl3 aqueous solutions. The results revealed that CMC mainly contributed to increasing the swelling as a result of strong water adsorption, whereas QC played a role in the controlling of the charges in the QC/CMC system, leading to the pH sensitivity.

Self-assembled micelles based on hydrophobically modified quaternized cellulose for drug delivery

Novel amphiphilic cationic cellulose (HMQC) derivatives carrying long chain alkyl groups as hydrophobic moieties and quaternary ammonium groups as hydrophilic moieties were synthesized. Structure and properties of the amphiphilic cellulose derivatives were characterized by elemental analysis, FT-IR, 1H NMR, ζ-potential measurement, dynamic light scattering (DLS), fluorescence spectroscopy and transmission electron microscopy (TEM). The results revealed that HMQCs can be self-assembled into cationic micelles in distilled water with the average hydrodynamic radius of 320–430nm. The cytotoxicity study showed that the HMQC exhibited low cytotoxicity. Prednisone acetate, a water insoluble anti-inflammation drug, was chosen as a model drug to investigate the utilization of self-assembled HMQC micelles as a delivery carrier for poorly water-soluble drugs. The study indicated that the prednisone acetate could be incorporated effectively in the self-assembled HMQC micelles and be controlled released.

Effect of Molecular Weight and Degree of Substitution of Quaternized Cellulose on the Efficiency of Gene Transfection

Quaternized celluloses (QCs) with different molecular weight (M(w)) and degree of cationic substitution (DS) were homogeneously synthesized in NaOH/urea aqueous solutions and were studied as gene carriers. QCs were evaluated for efficacy of nanoparticle formation, DNA binding efficiency, morphology, and in vitro gene transfection efficiency. The factors affecting the transfection efficiency, e.g., M(w), DS, and N/P ratios, have been evaluated. The cytotoxicity of QCs and QC/DNA complexes were evaluated in 293T cells and were found to be relatively low compared with 25 kDa PEI and PEI/DNA complex, which increased slightly with increasing of M(w) and DS. All QCs obtained could bind DNA efficiently, and QC/DNA complexes exhibited effective transfection in comparison to the naked DNA. More importantly, the QC/DNA complexes, were stable and the transfection efficiency was not inhibited in the presence of serum. The results revealed an important combined effect between M(w) and DS of QCs in determining transgene expression, and QCs with M(w) of about 8 x 10(4) g/mol and DS of about 0.6 displayed relatively higher transfection efficiencies attributed to the intermediate stability.

Flocculation Properties and Antimicrobial Activities of Quaternized Celluloses Synthesized in NaOH/Urea Aqueous Solution

Three water-soluble quaternized cellulose derivatives (QCs) with degree of substitution (DS) values of 0.38, 0.50, and 0.74 were synthesized in NaOH/urea aqueous solutions. The flocculation charact...

Preparation and Characterization of Novel Quaternized Cellulose Nanoparticles as Protein Carriers

Quaternized cellulose (QC) nanoparticles were prepared in distilled water by ionic crosslinking of QC with sodium tripolyphosphate (TPP) for the first time. BSA as a model protein drug was used to investigate the loading and release features of the nanoparticles. The results indicated that QC nanoparticles had high loading efficiency and capacity for BSA. The in vitro BSA release of the QC nanoparticles displayed a burst effect in the first 2 h and then a slow continuous release. Nanoparticles with a higher DS of QC showed a decrease in particle size, an increase in zeta potential, a higher loading efficiency and a slower drug-release profile. These studies demonstrated that QC nanoparticles are potential protein carriers, and that their physicochemical properties and release profile could be easily adjusted.

Homogeneous Quaternization of Cellulose in NaOH/Urea Aqueous Solutions as Gene Carriers

Quaternized celluloses (QCs) were homogeneously synthesized by reacting cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) in NaOH/urea aqueous solutions. The structure and solution properties of the QCs were characterized by using elemental analysis, FTIR, (13)C NMR, SEC-LLS, viscometer, and zeta-potential measurement. The results revealed that water-soluble QCs, with a degree of substitution (DS) value of 0.20-0.63, could be obtained by adjusting the molar ratio of CHPTAC to anhydroglucose unit (AGU) of cellulose and the reaction time. The QC solutions in water displayed a typical polyelectrolyte behavior, and the intrinsic viscosity ([eta]) value determined from the Fuoss-Strauss method increased with increasing DS value. Moreover, two QC samples (DS = 0.46 and 0.63) were selected and studied as gene carriers. The results of gel retardation assay suggested that QCs could condense DNA efficiently. QCs displayed relatively lower cytotoxicity as compared with PEI, and QC/DNA complexes exhibited effective transfection compared to the naked DNA in 293T cells. The quaternized cellulose derivatives prepared in NaOH/urea aqueous solutions could be considered as promising nonviral gene carriers.