Alginate/BSA/montmorillonite composites with enhanced protein entrapment and controlled release efficiency

Novel pH sensitive alginate-protein-clay composite beads were investigated for the in vitro oral delivery of the model protein, bovine serum albumin (BSA). X-ray diffraction (XRD) results revealed that BSA enter between layers of montmorillonite (MMT) by expanding interlayer distance and finally an exfoliated structure forms in the alginate hydrogel. MMT incorporation increases protein entrapment efficiency to 78%, compared to 40% of conventional alginate beads. The release ratio of BSA from composite beads is 9-13% depending on MMT contents after around a 2 h stay in gastric fluid. More importantly, no BSA release is detected until 60-90 min after the first contact time of beads with gastric solution. The presence of clay in alginate beads prevents burst release in higher pH of intestine by slowing release rate of BSA to 45-55% within around 9 h, resulting in a potential matrix for intestinal release of protein drugs.