Carboxymethyl gum katira: synthesis, characterization and evaluation for nanoparticulate drug delivery

In the present study a carboxymethyl derivative of gum katira was synthesized and explored for drug delivery applications. Carboxymethyl functionalization was achieved by reacting it with monochloroacetic acid under alkaline conditions. The modified gum was found to have a degree of carboxymethyl substitution of 0.6. Carboxymethyl modification was confirmed by FT-IR study. Thermal studies revealed higher thermal stability, while X-ray diffraction patterns showed increase in crystallinity of the carboxymethyl derivative. SEM study showed that carboxymethylation changes thin flaky, smooth surface particles into polyhedral sharp edged particles with a rough surface. Further, the preparation of polyelectrolyte complex nanoparticles of carboxymethyl gum katira and chitosan was optimized using 2-factor, 3-level central composite experimental design. The optimal calculated parameters were concentrations of carboxymethyl gum katira (0.26%, w/v) and chitosan (0.03%, w/v), which provided polyelectrolyte nanoparticles of size 269 nm and ofloxacin entrapment of 83.65%. The nanosuspension was found to release 92% of ofloxacin in 24 h, following Higuchi's release kinetics with the mechanism of release being Super Case-II transport. An ophthalmic nanosuspension of ofloxacin (0.3%, w/v) formulated using the optimized batch showed slightly higher apparent corneal permeability of ofloxacin than the aqueous solution of ofloxacin across the isolated porcine cornea. Further, the histological studies on corneas treated with ophthalmic nanosuspension revealed corneal biocompatibility. In conclusion carboxymethyl gum katira possess an excellent potential for exploring polyelectrolyte nanoparticulate ocular drug delivery.