**3. Alginate metal complexes preparation by Ionic crosslinking**

The ease of beads preparation and the mild conditions of alginate metal complexes preparation make it very unique compared to other polysaccharides. The ability to ion binding is selectively linked to the guluronate units (G). The M/G ratio, G-block length, and sequence of M and G blocks are the most important factors affecting the resulted alginate complexes.

Alginate forms hydrophilic gels by interaction with multivalent metal ions [9]. Since alginate gel can easily be formed by this ionic interaction in an aqueous medium; gel beads are commonly obtained by dropping solutions of sodium alginate into solutions of ion metal chloride [11–21], **Figure 2**. Generally, calcium chloride is one of the most commonly used as an ionically cross-linked agent

*Alginate Metal Complexes and Their Application DOI: http://dx.doi.org/10.5772/intechopen.98885*

**Figure 2.** *Alginate gelation by ionic interaction between alginate and a multivalent cation.*

to alginate. On the other hand, the gelation rate is depending on many factors, such as congealing time, temperature, and congealing sequence in the case of mixed beads (have two ion types). The formed egg-box has cavities between the G blockchains and the multivalent cation. In which the cavity fits the used cation [9].
