An okra polysaccharide (Abelmoschus esculentus) reinforced green hydrogel based on guar gum and poly-vinyl alcohol double network for controlled release of nanocurcumin

A novel green hydrogel (PGCO) of Okra (Abelmoschus esculentus) mucilage-reinforced poly-vinyl alcohol-guar gum (PG) cross-linked by citric acid containing nanocurcumin (NC) as a model drug is reported. The citric acid (CA) cross-linked hydrogel (PGC) without okra is also prepared. The hydrogels are characterized using FTIR, XRD, FE-SEM, and TGA techniques. Okra reinforced green hydrogel (PGCO) provided comparable swelling behaviour with better mechanical and thermal properties compared to the neat PGC hydrogel. Network parameters of PGC and PGCO hydrogels are estimated using Flory-Rehner equation and strong correlation between the cross-link density and swelling behaviour is established. 45.68 % NC loading in the PGCO hydrogel is achieved. Release study in phosphate buffer (PB) of pH 7.4 provided sustained release of NC over a period of 100 h. The release study of NC followed primarily the Korsmeyer-Peppas model with less-Fickian diffusional character (n < 0.5). The average diffusion coefficients of NC and curcumin are found to be 3.52 × 10-5 cm2 s-1, and 3.43 × 10-5 cm2 s-1 respectively demonstrating the quick release of NC in early time, which is a pre-requisite in drug delivery. The study provides initial evidence of the usefulness of okra mucilage in green hydrogel development and drug delivery applications.