Cellulose acetate/AgNPs-organoclay and/or thymol nano-biocomposite films with combined antimicrobial/antioxidant properties for active food packaging use

Nano-biocomposite films based on plasticized cellulose acetate/triethyl citrate (CA/TEC) were prepared with silver nanoparticles (AgNPs)/gelatin-modified montmorillonite nanofiller (AgM) and thymol (Th). AgNPs were biosynthesized in situ the clay using Curcuma longa (C. longa) tuber extract. Full characterization of clay and the formulated films was conducted including morphological, physical and functional properties. From the results, the AgNPs showed spherical shape, face centred cubic crystalline structure, and small average size with narrow distribution. Intercalated structure of films was achieved with some exfoliated platelets and clay aggregates. The glass transition temperature (Tg) of CA increased slightly by the added clay but decreased by Th due to its plasticizing effect. Also, the thermal stability of CA was enhanced only by the added clay. Increasing contents of both additives into films declined the optical clarity but enhanced greatly the UV barrier ability. The clay improved the tensile and oxygen barrier properties, while the Th initiated an antagonist effect. Besides, the radical 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) tests highlighted antioxidant activities of Th-included films. The films showed antimicrobial activities against bacteria and fungi, where Escherichia coli (E. coli) was the most sensitive, with an efficient growth inhibition in vapour-phase method. These materials with antimicrobial/antioxidant properties are promising active packaging

Fe3O4 imbuing carboxymethyl cellulose/dextran sulfate nanocomposite hydrogel beads: an effective adsorbent for methylene blue dye pollutant

In this study, initially synthesized magnetic nanoparticles modified with citrate ions (MNPs/m-MNPs) were entrapped in aluminum-carboxymethyl cellulose/dextran sulfate beads to form hybrid nanocomposites (m-MNPs-C/D0.5) using a simple two-pot method. Sodium dodecyl sulfate surfactant was employed to develop a porous interconnected structure. The synergistic effect of the hybrid nanocomposites was studied for the parametric adsorption of methylene blue dye pollutant. The swelling ability of hybrid hydrogels was also studied for different solution pH. The results clearly indicated that equilibrium was reached faster at about 3 h for the m-MNPs-loaded magnetic beads (m-MNPs-C/D0.5), whereas at 6 h for the MNPs-loaded beads (MNPs0.4-C/D0.5) and the unloaded simple ones (MNPs0-C/D0.5). Experimental data modeling of adsorption kinetics and isotherms as well as thermodynamic study showed a good correlation with pseudo-second order kinetic and Langmuir models while the adsorption process on magnetic beads was exothermic. The maximum adsorption capacity for MNPs0-C/D0.5 and the optimized m-MNPs0.3-C/D0.5 hydrogel were 380 and 529 mg g−1, respectively. Furthermore, all hydrogels were perfectly regenerated and then reused for five adsorption-desorption cycles without apparent loss of stability that confirms their consideration as alternative and effective adsorbents for wastewater treatment. The manufactured beads were characterized by scanning electron microscopy/energy dispersive X-Ray, dynamic light scattering, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometer and fourier-transform infrared spectroscopy

Swelling kinetics, mechanical properties, and release characteristics of chitosan-based semi-IPN hydrogels

Two series of pH-sensitive semi-interpenetrating network hydrogels (semi-IPN) based on chitosan (CS) natural polymer and acrylamide (AAm) and/or N-hydroxymethyl acrylamide (HMA) monomers by varying the monomer and CS ratios were synthesized by free radical chain polymerization. 5-Fluorouracil (5-FU), a model anticancer drug, has been added to the feed composition before the polymerization. The characterization of gels indicated that the drug is molecularly dispersed in the polymer matrix. The swelling kinetics of drug-loaded gels have decreased with increased HMA content at 37 degrees C in both distilled water and buffer solutions with a pH of 2.1 or 7.4. Elastic modulus of the gels increased with the increase in HMA content and higher CS concentration enhanced the elastic modulus positively. Moreover, cumulative release percentages of the gels for 5-FU were ca. 10% higher in pH 2.1 than those in pH 7.4 media. It was determined that they can be suitable for the use in both gastric and colon environments. (C) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41886