Dispersion of chitosan nanoparticles stable over a wide pH range by adsorption of polyglycerol monostearate

We have developed stable chitosan colloids over a wide pH range without cross-linkers or gelling agents. The colloid was prepared using chitosan nanoparticle obtained from pulverization of bulk chitosan powder, followed by surface treatment using small amount of ascorbic acid (AA) and polyglycerol monostearate (PGMS) in water. Chitosan nanoparticles were well dispersed in a diluted AA solution due to the protonation of the chitosan chain on the surface. And then, the addition of PGMS led them to exhibit highly stable dispersion even in alkali conditions and 50 °C. The hydrodynamic diameter of the colloid was monitored using dynamic light scattering and the real image of the colloid was obtained using cryo-electron microscope measurement. This chitosan colloid will be useful for developing food ingredients or drug carrier templates that should be stable over a wide pH range.

Zinc oxide-decorated polypyrrole/chitosan bionanocomposites with enhanced photocatalytic, antibacterial and anticancer performance

Bio-nanocomposites were synthesized via grafting polypyrrole/ZnO onto chitosan chain for the photodegradation of organic pollutants and biomedical applications.

Highly selective oxidation of toluene using air over [Fe(III)TPP]Cl supported on chitosan

The highly selective catalytic oxidation of toluene with air to benzaldehyde and benzyl alcohol in the liquid phase has been studied with the use of iron tetraphenylporphyrin (Fe TPP) supported on chitosan (CTS), (Fe TPP/CTS). The rates of toluene conversion and selectivity (aldehyde + alcohol) were subject to the reaction temperature, air pressure, and amount of iron tetraphenylporphyrin. By the use of the Fe TPP/CTS, containing 2 mg of iron tetraphenylporphyrin as catalyst, toluene oxidation with air under the optimum conditions of 190 °C and 0.6 MPa produced benzaldehyde and benzyl alcohol at 90% selectivity and 5.4% conversion of toluene, the mole turnover of the catalyst was about 6 × 106, and it could be reused efficiently for one more time. It is suggested that the amine groups (–NH2) on the chitosan chain act as a key assistor to the catalysis of Fe TPP for toluene oxidation. Compared with the conventional method of synthesizing benzaldehyde and benzyl alcohol, the new method has the advantages of reduced environmental pollution, higher selectivity for the two main products, and easy recovery of the catalyst.Key words: chitosan-supported iron porphyrin, catalysis, toluene oxidation, benzaldehyde, benzyl alcohol.