Investigating the effect of freezing temperature and cross-linking on modulating drug release from chitosan scaffolds

The aim of this study was to investigate the effect of altering design variables like cross-linking and freezing temperature (at a time) on morphology of freeze-dried chitosan scaffolds and modulation of release of Diclofenac sodium (model drug). Freeze-dried chitosan scaffolds produced at − 80 °C, cross-linked with genipin, showed swelling of 163.52 ± 9.95% with sustained drug release of 26.37 ± 10.47% over 24 h (P < 0.05). In comparison, uncross-linked scaffolds produced at − 80 °C showed higher swelling of 173.58 ± 8.23% and drug release of 28.67 ± 2.40% (P < 0.05). Uncross-linked scaffolds produced using freezing temperature of − 20 °C also showed higher swelling of 228.77 ± 9.84% and release of 30.58 ± 3.25% (P < 0.05). Release kinetics followed Higuchi model with Fickian diffusion, thereby indicating a swelling-dependent release. Altering the design parameters also showed significant changes in pore size and porosity, thereby supporting the swelling and drug delivery behavior from scaffolds.