Radiation grafting of N-vinylcaprolactam onto nano and macrogels of chitosan: Synthesis and characterization

•N-vinylcaprolactam was grafted onto CS macro and nanogels by γ radiation.•Swelling percentage was higher in grafted CS nanogels due to higher surface.•Release of 5-FU was higher in grafted CS macrogels than nanogels.•Release time of CS nano and macro gel systems was enough for therapeutic procedures.

The aim of this study was to synthesize chitosan hydrogels, in macro- and nano-size, grafted with N-vinylcaprolactam (NVCL) using gamma radiation, and evaluate their potential application as a drug delivery system, using 5-fluorouracil (5-FU) as a model drug. The effect of dose and monomer concentration in the grafting process was studied, and the materials were characterized by FTIR, TGA, DLS, SEM and AFM. Higher grafting percentages were observed for the nanogels system. Although both the grafted macro- and nanogels, (net-CS)-g-NVCL, showed a response to pH (4.75) and temperature (31–33 °C), the nanogels showed a better swelling response to both stimuli because of their higher surface area. Both systems were able to load 5-FU in small amounts (2–3.5 mg g−1) and the release was sustained for more than 12 h, showing that the modified macro and nanogels can be a potential alternative for the administration of drugs.