Dual responsive GG-g-PNPA/PIPAM based novel hydrogels for the controlled release of anti- cancer agent and their swelling and release kinetics

This study includes the synthesis of amino acid graft copolymer from N - Acryloyl- L -phenylalanine amino acid and Guar gum polymer through free radical polymerization. Then the dual responsive (pH & temperature) hydrogels are synthesized by employing free radical cross linking polymerization using graft copolymer, N -isopropyl acrylamide and 2-(dimethylamine) ethylmethacrylate using N,N′ -methylenebisacrylamide as a cross-linker and ammonium per sulfate as initiator. The structural properties of the hydrogels are evaluated by the determination of various network properties such as mesh size, crosslink density, Flory-Huggins interaction parameter, volume fraction in the swollen state and the average molecular weight of the polymer chain between two neighboring cross links. Dynamic and equilibrium swelling studies of hydrogels are performed in distilled water, pH 1.20 and pH 7.40 solutions at 25 °C and 37 o ± 5 °C, swelling capacity in various salt solutions and corresponding swelling kinetic parameters are also calculated. Grafting, cross linking and structural changes are studied by fourier transform infrared and scanning electron microscope, distribution of imatinib mesylate drug in hydrogel is confirmed by X-ray diffraction, differential scanning calorimetry, thermo gravimetric analysis. Drug loading and encapsulation efficiency of Imatinib mesylate in various formulations of the hydrogels are also studied. The in-vitro drug release studies are performed in pH 1.20 and 7.40 phosphate buffer solutions at different amounts of cross linker, monomer and graft copolymer and temperature. The mode of drug release mechanism is analyzed by various kinetic models such as zero order, First order, Higuchi Square root, Hixson-Crowell cube root and Koresmeyer-Peppas equations.