Crosslinked galactomannan based polymeric network for sustained drug delivery system

Galactomannan functionalization represents a significant advancement in developing sustainable and biocompatible materials required for industrial applications. The study focuses on the development of a sustainable, eco-efficient crosslinked product of guar gum utilising malic acid, a green, natural, abundant, inexpensive and water-soluble dicarboxylic acid through a green chemistry approach without requiring any catalyst. The introduction of 2-hydroxy-1,4-butane dioates were confirmed by FTIR and NMR (1D and 2D) spectroscopy. The effect of reaction parameters such as material-to-liquor ratio, crosslinker conc. (0.0074 mol to 0.0223 mol), curing temp (115℃ - 145℃), and curing time (4,7,10) minutes was analysed. The product obtained at a curing temperature of 130℃ favoured a higher degree of di-esterification and achieved favourable green metrics, including low PMI and RMI values from moderate to high, an atom economy (92.14%), reduced E-factor (<1) and EQ values. Thermal analysis showed that the activation energy of native and modified guar gum was 53 kJ/mol and 67.85 kJ/mol, respectively, depicting higher stability of the modified product. Crosslinking significantly improved tensile strength (TS) and elongation at break (%E), validating the flexibility of the product. At the same time, the compact structure formation after crosslinking reduces the diffusion of water molecules, thereby lowering water vapour permeability (0.0644 + 0.0021 g/m 2 / day). The crosslinked product exhibited controlled release of naproxen based on pH-responsive behaviour, making it appropriate for colon-targeted drug delivery. The drug release data were best fitted to the Korsmeyer-Peppas kinetic model, and the diffusional exponent (n) values suggested a non-Fickian anomalous diffusion-controlled mechanism for the release of the drug.