Investigation on ionical cross-linking of alginate by monovalent cations to fabrication alginate gel for biomedical application

Abstract

It was reported that monovalent cations and Mg2+ ions cannot crosslink alginate to form gels while bivalent cations like Ca2+, Ba2+, Sr2+, Co2+, Ni2+, Zn2+ and Mn2+ions can, so alginate gel beads can be easily produced by dropping an alginate droplet in a bath of metal ion solution. This ready gel-forming ability at mild condition can avoid the inactivation of the drugs, proteins, cells and enzymes and makes alginate extensively used for bioencapsulation. Here, ionically crosslinking of alginate by a monovalent cation, Ag+ ion, was explored. The conditions for the formation of gel beads and the structure and properties of the as-prepared alginate beads were studied. In addition, the possibility of loading drug in the alginate beads was also investigated. The results demonstrate that Ag+ ions do induce gelation of alginate and can be applied to fabricate alginate beads and drug loaded beads like those prepared by using Ca2+ as crosslinking agent.