Graft Copolymerization of 2-Hydroxyethyl Methacrylate onto Chitosan Using Radiation Technique for Release of Diclofenac

Chitosan (CS) was modified with 2-hydroxyethyl methacrylate (HEMA) by gamma radiation to improve its water absorption ability and use it as a drug delivery system. For this, HEMA was grafted by direct method onto dissolved CS (homogeneous) or powder CS (heterogeneous) using doses less than 20 kGy. The grafting percentage was easily controlled changing the homogeneity of system. Low and medium grafting percentages (20-70%) were obtained with the heterogeneous method, while the homogeneous method yielded higher grafting percentages (∼340%). CS-g-HEMA was confirmed using infrared spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA) and X-ray diffraction (XRD). In addition, the swelling behaviour, critical pH, and drug absorption, using diclofenac as a model, were also evaluated. Results show that the presence of HEMA had a positive effect on swelling and the drug uptake when low grafting percentages were used; CS-g-HEMA (17%) swelled in water (261%) and loaded better amounts of diclofenac (1.5 mg g^-1) than CS (0.97 mg g^-1). [Figure not available: see fulltext.]