Team:ETH Zurich/lab/bead

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[[File:ETH2014_BeadColonies.jpg|right|300px|thumb| The green spots are ''E. coli'' colonies inside an alginate bead]]
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[[File:ETH2014_BeadColonies.jpg|right|300px|thumb| '''Figure 2 The green spots are ''E. coli'' colonies inside an alginate bead''']]
Na<sup>2+</sup> alginate is a viscous liquid, however, upon addition multivalent ions such as Ca<sup>2+</sup> cross-linking of the polysaccharides occurs. Thus gelling of alginate can be achieved by the addition of a Ca<sup>2+</sup>. For encapsulation the cells or macromolecules are added to Na<sup>2+</sup> alginate and subsequently immobilized during the gelling process. In fact, the encapsulation process is mild and compatible with most living cells. The high porosity of the ionically cross-linked polysaccharide lattice allows diffusion of nutrients and other substances into and out of the bead. This property of Ca<sup>2+</sup> alginate allows cultivation of bacteria inside beads and does not prevent communication via small molecules between colonies of different beads. Substances such as phosphate or EDTA are sequestrating Ca<sup>2+</sup> and thus destabilizing the alginate gel<sup>[[Team:ETH_Zurich/project/references#refEmergence|[25]]]</sup>. This fact should be considered when choosing the cultivation medium.  
Na<sup>2+</sup> alginate is a viscous liquid, however, upon addition multivalent ions such as Ca<sup>2+</sup> cross-linking of the polysaccharides occurs. Thus gelling of alginate can be achieved by the addition of a Ca<sup>2+</sup>. For encapsulation the cells or macromolecules are added to Na<sup>2+</sup> alginate and subsequently immobilized during the gelling process. In fact, the encapsulation process is mild and compatible with most living cells. The high porosity of the ionically cross-linked polysaccharide lattice allows diffusion of nutrients and other substances into and out of the bead. This property of Ca<sup>2+</sup> alginate allows cultivation of bacteria inside beads and does not prevent communication via small molecules between colonies of different beads. Substances such as phosphate or EDTA are sequestrating Ca<sup>2+</sup> and thus destabilizing the alginate gel<sup>[[Team:ETH_Zurich/project/references#refEmergence|[25]]]</sup>. This fact should be considered when choosing the cultivation medium.  
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Revision as of 23:25, 17 October 2014

iGEM ETH Zurich 2014