## 4 Discussion
Notably, Streptococcus themselves tend to form pairs or chains in these cases. Because of this reason, the pairs and chains would assemble in larger agglomerates under the presence of LDH due to the electrostatic interaction. Individual chains or pairs of FKC would be well dispersed in the presence of KA because of electrostatic repulsion. Even though we could expect some pairs or chains to be broken into single cells in the presence of KA, as it was previously reported, it was expected that the mechanical stress separated chained streptococci into single cells [43]. As a result of the study, this hypothesis was clearly demonstrated in the DLS analysis (Figure 1 and Table 1) and in the SEM observations (Figure 2). As has been seen, the KA dramatically enhanced the encapsulation efficiency, while LDH slightly hindered the encapsulation of FKC (Table 2). It is not easy to fully comprehend the effect of the nanoclays at this stage. However, we could suggest several explanations. First, the alginate-Ca2+ cross-linking occurs readily and homogeneously in the aqueous system, as soon as the alginate solution meets the Ca2+ cations [44]. During this process, the degree of homogeneous dispersion is considered to affect the encapsulation efficiency whereby the more homogeneously dispersed, the easier alginate-Ca2+ network can capture the FKC moiety. In this instance, Table 1 shows that the PQI of the FKC + KA mixture was 20% lower than that of FKC only, suggesting the possibility of FKC chain separation into single cells. Furthermore, an increase in freely floating FKC facilitated encapsulation into alginate beads. On the other hand, the FKC + LDH mixture was clearly shown to produce large lumps; and therefore the alginate-Ca2+ network could not efficiently encapsulate large lumps that might produce a type of sediment without being encapsulated. It is important to realize that the release behavior was also strongly affected by the existence of clay nanoparticles. As shown in Table 3, FKC alone-encapsulated alginate beads could release ~2% of FKC, while the FKC + clay mixture containing alginate beads did not significantly show the release amount. In an aqueous system, the dried alginate bead is expected to absorb water. As time goes by, the more water that gets into the alginate beads produced the characteristic resulting in a swelling and release of the encapsulated moiety. In this way, the clay nanoparticles, LDH and KA are known to absorb water easily when they form a composite with the polymer [45; 46]. Therefore, clay nanoparticles in the alginate beads are expected to absorb water instead of alginate side chains, consequently prohibiting the swelling of alginate beads. In the gastric condition, all alginate beads regardless of the presence of clay nanoparticles preserved the encapsulated FKC efficiently until 4 h. This can be explained by the chemical nature of alginate. As noted, the guluronate groups coordinate with Ca\({}^{2+}\) to form cross-links. However, mannuronic acid groups remained because of their acidic property. Generally speaking, at a low pH, mannuronic acid loses solubility dramatically to repel water moiety [35; 47]. In this way, alginate beads can preserve an intact FKC at a gastric pH. In the intestinal condition, because of the high pH and various electrolyte conditions, a significant FKC release was apparent for all alginate beads. Both clay nanoparticles increased their FKC release which was attributed to the alginate network disturbed by the nanoparticles. As shown in Figure 3, the inner wall of the alginate only bead was homogenously patterned. However, the addition of clay nanoparticles (Figure 5) altered the inner surface to be more heterogeneous. As a wedge is driven in a matrix, the clay nanoparticles were expected to make holes in the alginate matrix to release more FKC. More release was found in the FKC + LDH mixture since LDH could agglomerate FKC in large lumps, so a larger amount of FKC could be released out at one time.