Chitosan Polymer Matrix Research Articles

Preparation and properties of hybrid direct methanol fuel cell membranes by embedding organophosphorylated titania submicrospheres into a chitosan polymer matrix

Organophosphorylated titania submicrospheres (OPTi) are prepared and incorporated into a chitosan (CS) matrix to fabricate hybrid membranes with enhanced methanol resistance and proton conductivity for application in direct methanol fuel cells (DMFC). The pristine monodispersed titania submicrospheres (TiO 2) of controllable particle size are synthesized through a modified sol–gel method and then phosphorylated by amino trimethylene phosphonic acid (ATMP) via chemical adsorption, which is confirmed by XPS, FTIR and TGA. The morphology and thermal property of the hybrid membranes are explored by SEM and TGA. The ionic cross-linking between the –PO 3H 2 groups on OPTi and the –NH 2 groups on CS lead to better compatibility between the inorganic fillers and the polymer matrix, as well as a decreased fractional free volume ( FFV), which is verified by positron annihilation lifetime spectroscopy (PALS). The effects of particle size and content on the methanol permeability, proton conductivity, swelling and FFV of the membranes are investigated. Compared to pure CS membrane, the hybrid membranes exhibit an increased proton conductivity to an acceptable level of 0.01 S cm −1 for DMFC application and a reduced methanol permeability of 5 × 10 −7 cm 2 s −1 at a 2 M methanol feed.

Preparation and Characterization of Chitosan-Based Nanocomposite Films with Antimicrobial Activity

Four different types of chitosan-based nanocomposite films were prepared using a solvent-casting method by incorporation with four types of nanoparticles, that is, an unmodified montmorillonite (Na-MMT), an organically modified montmorillonite (Cloisite 30B), a Nano-silver, and a Ag-zeolite (Ag-Ion). X-ray diffraction patterns of the nanocomposite films indicated that a certain degree of intercalation was formed in the nanocomposite films, with the highest intercalation in the Na-MMT-incorporated films followed by films with Cloisite 30B and Ag-Ion. Scanning electron micrographs showed that in all of the nanocomposite films, except the Nano-silver-incorporated one, nanoparticles were dispersed homogeneously throughout the chitosan polymer matrix. Consequently, mechanical and barrier properties of chitosan films were affected through intercalation of nanoparticles, that is, tensile strength increased by 7-16%, whereas water vapor permeability decreased by 25-30% depending on the nanoparticle material tested. In addition, chitosan-based nanocomposite films, especially silver-containing ones, showed a promising range of antimicrobial activity.

Characterization and evaluation of chitosan matrix for in vitro growth of MCF-7 breast cancer cell lines

Biodegradable polymer scaffolds were prepared from chitosan with varying degree of deacetylation for in vitro culture of human breast cancer MCF-7 cell lines. These polymers were characterized in terms of functional groups by FTIR and swelling properties. Polymers having high degree of deacetylation showed better swelling properties irrespective of the molecular weight. These polymers were biocompatible and non-toxic towards human epithelial MCF-7 cell lines. Attachment kinetics of MCF-7 cell lines on to polymer scaffold was investigated and it was observed that polymer having high degree of deacetylation favored better cell attachment. In CPIII polymer scaffold having 80% degree of deacetylation, a maximum of 1 millions cells per mg pf polymer were adsorbed within 1 h. It appears that high swelling and high degree of deacetylation of chitosan helped in better adsorption of cancer cell lines. The cellular morphology of the attached cells on chitosan matrix was similar to that observed with regular plastic culture with the difference that, cells grew as three-dimensional clumps on chitosan matrix. Polymer having high degree of deacetylation not only favored better adsorption but also showed improved cell growth kinetics. Maximum cell concentration of 6.5×10 5 cells/ml was achieved in 5 days culture on CPIII polymer scaffold. The glucose consumption and lactate production pattern of the MCF-7 cell lines on chitosan polymer matrix were similar to that observed on cell growth on tissue culture flask. These results indicate that chitosan scaffold having high degree of deacetylation can be used for three-dimensional growth of MCF-7 cancer cell lines. Such in vitro 3D culture of cancer cells can thus be used as a model for the cytotoxic evaluation of anticancer drugs.