Graft copolymers of carboxymethyl cellulose with N-vinylimidazole: synthesis and application for drug delivery

Graft copolymers of sodium salt of carboxymethyl cellulose and N-vinylimidazole with different contents of the latter are synthesized by radical polymerization. Polymerization kinetics for all samples is researched by copolymer composition determination by UV spectroscopy, and it was found that it lasted 180 min. Percent of grafting calculated from FTIR data is in the range 31–59%, which correlated with GPC and static light scattering data. Aqueous solutions of the synthesized copolymers are characterized by dynamic light scattering (DLS), transmission electron microscopy, and zeta potential measurement. It was established that macromolecular particles of all synthesized copolymers possess non-spherical shape and negative electrokinetic potential value. The hydrodynamic radii of the polymer coils are 120–152 nm. It was found by DLS that macromolecular coils of all copolymers are stable in 0.15 M NaCl aqueous solution and in the physiological pH range which allows to apply them as vectors for targeted drug delivery. Interaction between paclitaxel (Ptx) and Na-CMC-g-PVI copolymer was studied by UV spectroscopy, FTIR, and TEM. Copolymer and Ptx complex formation proceeds by interaction of imidazole cycles and methylene backbone of Na-CMC-g-PVI copolymer and C=O groups and aromatic rings of Ptx. In vitro release kinetics was also researched in acidic and neutral media at 38 °C. Particularly, full release of paclitaxel is reached after 144 h. Release process of Ptx from copolymer particles is described by Korsmeyer–Peppas kinetic model and limited by molecular diffusion.