Citric acid crosslinking of mucilage from Cydonia oblonga engenders a superabsorbent, pH-sensitive and biocompatible polysaccharide offering on-off swelling and zero-order drug release

Present research demonstrated the crosslinking of Cydonia oblonga seeds hydrogel using citric acid (CA) and evaluated its stimuli-responsive swelling properties at different biomimetic pH, swelling/deswelling behavior against different fluids and sustained release potential in orally administered tablet formulation. Cross-linked C. oblonga hydrogel (CL-COH) was synthesized using four concentrations of CA, i.e., 1.25%, 2.5%, 5% and 10% and characterized through Fourier transform infrared (FTIR) spectroscopic analysis. CL-COH exhibited high swelling capacity at pH 6.8, 7.4 and in deionized water whereas, insignificant swelling was observed at pH 1.2. Swelling/deswelling response of CL-COH (2.5% CA) at pH 7.4 and 1.2, in deionized water and ethanol, and deionized water and normal saline were remarkable and reproducible results were obtained even after four cycles. Scanning electron microscopy (SEM) images of CL-COH indicated evenly distributed web of interconnected macro-pores. CL-COH was used as a pH-sensitive sustained release material for the preparation of oral tablet formulation of levosulpiride. In vitro drug release study revealed that the drug release followed zero-order kinetics and drug release mechanism was found as a super case II transport. Non-thrombogenic and non-hemolytic potential of CL-COH was ascertained through haemocompatibility studies. Therefore, CL-COH can be a versatile stimuli-responsive and biocompatible polysaccharide-based material for zero-order sustained release of drugs.