Effects of pH on the Shape of Alginate Particles and Its Release Behavior

Abstract

A vast majority of alginate particles exist as spheres in most practical uses, and both the particle shape and size are the key factors dominating the applications and performance of alginate gels. Therefore, it becomes an issue of great interest to investigate the aspheric alginate particles. As the first step, various shaped alginate particles were formed due to various pH values in gelation solutions. It was experimentally demonstrated that a low pH brought about an oblate shape, and particularly lower concentrations of both alginate and divalent cations resulted in a flattened oblate shape. Ba2+acting as a cross-linker had a less impact on the particle shape than Ca2+due to a higher affinity in alginate intermolecular cross-linking. With a larger surface area, an oblate particle offered a higher release rate than a spheric one.

The Size Stability of Alginate Beads by Different Ionic Crosslinkers

“…The bead sizes were obtained from recorded photographs and are expressed as the mean ± standard deviation. solution because the beads incubated in the Ca 2+ solution did not form sufficiently tightly and had a lower affinity than the beads incubated in the Ba 2+ solution [25,26]. At 300 minutes, the beads in high concentrations of crosslinkers were larger than those in low concentrations of crosslinkers.…”

Complex Polysaccharide-Based Nanocomposites for Oral Insulin Delivery

“…Because amine groups in CS are protonated, repulsive electrostatic forces appear among different chains. Therefore, no attractive electrostatic interaction among polyelectrolytes takes part, and hydrogen bonding among chains becomes the main force, determining the gelation of the alginate [44,45], as well as the interaction among PEG and poloxamer with polyelectrolytes. Nevertheless, given that under high ionic strength conditions no aggregation was observed, despite the screening of charges, it is more likely that the denaturation of the BSA, which occurred at pH 2, is the triggering process [46].…”

“…The opposite situation was found at pH 7.4. Carboxyl groups in alginate and the sulfate groups in DS are ionized [45]. Amine groups in CS are not ionized and CS becomes non-soluble.…”

Trigonella-foenum graecum l. seed mucilage-based mucoadhesive microspheres of diclofenac sodium

“…Sodium alginate is a negatively charge polymer that allows the reaction with positively charge ions present in the calcium chloride solution resulting in the formation of microsphere. 23 The microspheres general appearance was spherical with rough surfaces and light brown in colour due to the original pigmentation colour of the TFGSM.…”

“…These models were compared by calculating the squared correlation coefficient (R 2 ). 22,23 Following, the Korsmeyer-Peppas model was used in the in vitro release pattern evaluation of the formulations to distinguish between completing release mechanisms: Fickian release (diffusion-controlled release), non-Fickian release (anomalous transport) and case-II transport (relaxation-controlled release). When n is ≤0.43, it is Fickian release.…”