Microwaved schiff base dialdehyde cellulose-chitosan hydrogels for sustained drug release with DFT calculations

Dialdehyde cellulose (DAC) prepared from sugarcane bagasse (SC) by an eco-friendly, fast and low-cost microwave method was used for loading and sustained release of 4-aminoacetophenone (4-AAP). DAC was reacted with chitosan (Ch) and 4-AAP via a Schiff base reaction. FTIR analysis confirmed successful Schiff base formation between DAC and Ch, evidenced by the disappearance of the DAC aldehyde peak at 1716 cm⁻¹ and the appearance of the imine peak at 1631 cm⁻¹, as well as strong hydrogen bonding with incorporated 4-AAP, indicated by a shift in the O-H stretch from 3336 cm⁻¹ to 3330 cm⁻¹.Swelling studies showed increased water absorption with higher 4-AAP content, with 4-AAP@DAC/Ch2 demonstrating pseudo-second-order kinetics and non-Fickian diffusion. The DFT calculations revealed that the 4-AAP@DAC/Ch hydrogel exhibited enhanced stability and reactivity. A significantly reduced HOMO-LUMO energy gap, coupled with negative Pi values, indicated strong interactions between DAC, chitosan, and 4-AAP. The high adsorption energy further supported the observed slow drug release, validating the experimental findings.