Release profile of vitamin B6 from a pH-responsive BSA network crosslinked with genipin

The work provides insights into the effect of pH on the changing microstructural characteristics of swollen BSA networks and the concomitant release profiles of an entrapped bioactive compound. In doing so, a delivery vehicle was developed at ambient temperature with the native BSA molecule and genipin, a natural crosslinker. Ninhydrin assay, FTIR, X-ray, SEM and texture profile analysis documented successful crosslinking that resulted in matrices with distinct morphology and mechanical properties. Water infusion was monitored, which allowed estimation, with the modified Flory-Rehner theory, of microstructural parameters of the swollen network, including the polymer molecular weight between crosslinks and mesh size. Transportation of entrapped vitamin B6 from crosslinked BSA networks was followed over long periods of observation in release media of acidic, neutral and alkaline conditions. Utilisation of diffusion theory predicted the apparent diffusion coefficient and diffusion exponent for the release of the bioactive compound, which was correlated to the morphological characteristics of the crosslinked protein network via the change in pH.