Citric acid cross-linked glucuronoxylans: A pH-sensitive polysaccharide material for responsive swelling-deswelling vs various biomimetic stimuli and zero-order drug release

Abstract Herein, we report on the cross-linking of a glucuronoxylan isolated from Mimosa pudica (MP) seed and its stimuli (biomimetic) responsive properties, i.e., pH, saline and solvent responsive swelling-deswelling. Cross-linked MP hydrogel (CL-MPH) was prepared by esterification of MPH using citric acid (CA) as a cross-linking agent (CLA). Three products of different cross-linking degree were synthesized with different concentrations of CA and characterized by FTIR spectroscopic analysis. CL-MPH (with 5% CA) showed high swelling at pH 6.8, 7.4 and in deionized water while negligible swelling was observed in pH 1.2. This CL-MPH sample exhibited swelling-deswelling (on-off switching) behavior in water to ethanol, water to saline (0.9% NaCl) and basic (pH 7.4) to acidic (pH 1.2) buffer, respectively. Scanning electron microscope (SEM) analysis revealed the presence of interconnected macro-pores in CL-MPH. Tablets prepared with CL-MPH and diclofenac sodium were evaluated for sustained release potential of CL-MPH. Drug release kinetics and release mechanism followed zero-order and non-Fickian diffusion, respectively. Haemocompatibility studies revealed the non-thrombogenic and non-haemolytic potential of CL-MPH. Due to these attributes of CL-MPH; it can find its applications as a pH-sensitive smart biomaterial for targeted/controlled/sustained drug delivery systems.