Development of mucoadhesive hydrogels based on polyacrylic acid grafted cellulose nanocrystals for local cisplatin delivery.

To fabricate a mucoadhesive hydrogel with superior properties for local delivery of cisplatin (CDDP) to colorectal cancer, a hardcore bottle-brush polymer (HCBBP) was developed through grafting of poly(acrylic acid) (PAA) on cellulose nanocrystals (CNC) at 6, 9 and 12 CNC:PAA w/w ratios. The developed materials were characterized by acid-base titrations, FT-IR, electron microscopy, muco-rheological behaviour in the presence of mucin, in vitro drug release and anticancer activity against human HCT-116 colorectal cancer cells. The results showed CNC-g-PAA9 to have superior rheological behavior in the presence of mucin compared to CNC and other gels under study indicating beneficial mucoadhesive characteristics. CNC-g-PAA9:CDDP complex showed slow CDDP release causing a significant increase in IC 50 of the drug (> 3-fold) against HCT116 cells. The developed CNC-PAA9 hydrogel showed no intrinsic cytotoxicity on its own. The results point to a great promise for CNC-g-PAA9 as mucoadhesive hydrogels for local platinum delivery in colorectal cancer.

Sorption of 2,4-dinitroanisole (DNAN) on lignin.

The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg x hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40 degrees C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, deltaH0 equaled to 14 or 80 kJ/mol. To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.

Preparation of lignopolyols from wheat straw soda lignin.

Wheat straw soda lignin was modified and characterized by several qualitative and quantitative methods such as (31)P NMR spectroscopy to evaluate its potential as a substitute for polyols in view of polyurethane applications. Chemical modification of the lignin was achieved with propylene oxide to form lignopolyol derivatives. This was performed by a two-step reaction of lignin with maleic anhydride followed by propylene oxide and by direct oxyalkylation under acidic and alkaline conditions. The physical and chemical properties of lignopolyols from each method and the subsequent chain-extended hydroxyl groups were evaluated. Direct oxyalkylation of lignin under alkaline conditions was found to be more efficient than acidic conditions and more effective than the two-step process for preparing lignopolyol with higher aliphatic hydroxyl contents.