At present, plant-based hard capsule such as hydroxypropyl methylcellulose (HPMC) has a high demand in drug delivery application but the production process is expensive with limited reactant supply. κ-carrageenan has been used as a gelling agent in HPMC hard capsule production. This study aims to develop gum Arabic (GA)-κ-carrageenan biocomposite, a potential material to produce hard capsule. The GA-κ-carrageenan biocomposite films were prepared at different κcarrageenan weight ratios of 33% (GC33), 50% (GC50) and 67% (GC67) at constant concentration of polyethylene glycol and alginate. The control films of GA film and κ-carrageenan film were compared. The film and hard capsule formed from GC67 shows the highest tensile strength and capsule loop of 36.21 MPa and 34.11 N, respectively at 1058 mPa.s solution viscosity at 300 rpm shear rate. The hard capsule disintegrated at 7.30 min. The addition of GA is compatible to make the hard capsule surface smoother. Thus, this biocomposite has the potential to be developed for future hard capsule.

This work aims to evaluate carrageenan as a potential biocomposite for hard capsule in the drug delivery application. The interaction between carrageenan and isovanillin was studied by modeling their molecule electronic surface potential and enthalpy. Simulation results showed that the physical crosslinking is established at two points: hydroxyl (isovanillin)-sulfate (carrageenan) and aldehyde (isovanillin)-hydroxyl (carrageenan) with strong hydrogen bonds (H-bond) lengths of 1.74-1.79 Å. FTIR showed that isovanillin addition increased the intermolecular H-bond up to 57% as the OH-stretching is shifted from 3376 to 3356 cm_1. At 3 wt.% isovanillin concentration, the tensile strength of the biocomposite film increased to 49% and the hard capsule developed from the formulation solution disintegrated in 9min. Upon contact with water, the H-bonds broke and caused the carrageenan fragments to dissolve in deionized water. The disintegration and mechanical properties of the crosslinked carrageenan biocomposite film made from renewable and low price materials facilitate the application of the film as hard capsules for drug delivery.

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