A DFT based analysis of adsorption of Hg2+ ion on chitosan monomer and its citralidene and salicylidene derivatives: Prior to the removal of Hg toxicity.

A Density functional theory based study of adsorption of the toxic metal Hg (II) ion by chitosan monomer and two of its derivatives; citralidene and salicylidene chitosan, has been performed. The effect of structural features on the stability of studied complexes has been analyzed by using Gaussian03 software package. All the possible conformations of these adsorbents were studied using the global minimum geometries. All the adsorbing sites were studied by placing the metal ion on the centroid of the atoms and the stable conformer of the adsorbent-metal ion complex was identified. Interaction between Hg (II) and the adsorbents is found to be electrostatic. Metal ion binding with nitrogen atom is stronger than that with oxygen atoms in all the cases as the charge density of nitrogen is enhanced on Schiff base formation. The advantage of derivatives over chitosan monomer is their stability in acidic media. ΔE value of the complexes are in the order SC-Hg (II)>chitosan-Hg (II)>CC-Hg (II) which indicates that the stability of complexes increases with increase in energy gap. The study reveals that aromatic Schiff base derivatives of chitosan is better for Hg(II) intake than aliphatic derivatives.

Flexible chitosan-nano ZnO antimicrobial pouches as a new material for extending the shelf life of raw meat.

As a breakthrough to open up the industrial use of novel environmentally benign packaging material, we propose the first report on portable chitosan-ZnO nano-composite pouches that will serve as elite entrants in smart packaging. A facile, one pot procedure was adopted for the preparation of the C-ZnC films. In order to tune the property of C-ZnC films, four different composite films were prepared by varying the concentration of ZnO. The prepared films were found to be much superior when compared to bare chitosan and other conventional films. Two bacterial strains that commonly contaminate in packed meat were selected as target microbes to elucidate the antimicrobial activity of the prepared C-ZnO film. Detailed investigations revealed that the antimicrobial efficiency is linearly related to the amount of ZnO nano-particles in the composite. The C-2 films exhibited excellent antimicrobial activity and was fabricated into packaging pouches for raw meat. The prepared pouches showed significant action against the microbes in raw meat owing to its complete inhibition of microbial growth on the sixth day of storage at 4°C. The C-2 pouches stand as a top-notch material when compared to polyethylene bag in extending the shelf life of raw meat.

Applications of chitosan powder with in situ synthesized nano ZnO particles as an antimicrobial agent.

ZnO nanoparticles are immobilized on the chitosan matrix by an in situ sol-gel conversion of precursor molecules in a single step. Three different composites are prepared by varying the concentration of sodium hydroxide with same quantity of chitosan and zinc acetate dihydrate. The composites were characterized by FTIR, UV-visible spectra, and XRD. The observed decrease in the band width corresponding to OH and NH2 group in the composites is ascribed to the reduction of hydrogen bond due to the presence of ZnO nanoparticles. The direct evidence of the immobilization of nano ZnO particles in the matrix was identified by SEM. The average particle size values obtained for the nanoparticles, using Debye-Scherrer equation from XRD, is in the range 10-18nm. Optical studies proved that all the three composites studied have the same band gap energy (3.28eV) in agreement with the reported values. We observed that the composites possess excellent antimicrobial activity against Gram negative bacteria Escherichia coli (E. coli) and Gram positive bacteria Staphylococcus aureus (S. aureus) than chitosan. Based on the above studies, the biocompatible, eco-friendly and low-cost composite powder could be applied in various fields as an antimicrobial agent.

Virtual screening of molecular properties of chitosan and derivatives in search for druggable molecules.

Druggability of chitosan monomer and Schiff bases as well as reduced Schiff base derivatives of chitosan were examined. Oral bioavailability and bioactivity of all these molecules against selected drug targets as well as ADME/Tox studies were conducted. All the molecules satisfied Lipinski's rule of five confirming their oral bioavailability. They also show good bioactivity score for protease and enzyme inhibition. ADME/Tox studies conducted shows that almost all the derivatives are free from toxicity risks. It is observed that these molecules exhibit fairly good drug score and are orally viable molecules. Chelation of chitosan and its derivatives with essential metal ions might be the mechanism driving their bioactivity. Thus chitosan monomer and the derivatives studied, can serve as good lead molecules for further research.