Algins structure

While most appfications were performed in suspended cell cultures some authors showed that the application of NADH-dependent fluorescence monitoring is also possible in immobifized cell systems. Here the growth of Clostridium acetobutylicum and the Saccharomyces cerevisiae immobilized in different calcium alginate structures was studied. However, calibration of the culture fluorescence signal with the biomass concentration was not possible but qualitatively an increasing biomass also led to an increase in the fluorescence signals. 

Alginate structure can be used in order to design smart materials for special applications. However, when a modification of the backbone is carried out we always must ask what happens to the stability of the pyranoside ring. Since the acetal... 

On the other hand, alginate structure can also be chemically modified in order to design smart materials for special applications. The reactivity of alginate functional groups can be exploited as a potential tool for the modification of interesting properties such as solubility, hydrophobicity, and physicochemical and biological characteristics. 

Agulhon P, Robitzer M, David L, Quignatd F (2012) Structural regime identification in ionotropic alginate gels influence of the cation nature and alginate structure. Biomacromolecules 13 215-220... 

FIG. 9.2 External structures in animals held together by oxygen and calcium. Shown are shell structure, bone structure, alginate structure, keratin, chitin, and cellulose structure. Many of these links are cut by external copper and zinc enzymes. 

Commercial applications for polysaccharides include their use as food additives, medicines and industrial products. Although plant polysaccharides (such as starch, agar and alginate) have been exploited commercially for many years, microbial exopolysaccharides have only become widely used over the past few decades. The diversity of polysaccharide structure is far greater in micro-organisms compared to plants and around 20 microbial polysaccharides with market potential have been described. However, microorganisms are still considered to be a rich and as yet underexploited source of exopolysaccharides. 

The resulting enzyme-containing microcapsules (which can contain different enzymes in different capsules, as was the case here) were then embedded within a Ca-alginate bead, designated a capsules-in-bead structured microreactor (Scheme 5.7). 

One example for a chemically defended zooplankton species is the Antarctic pteropod Clione antarctica. This shell-less pelagic mollusk offers a potentially rich source of nutrients to planktivorous predators. Nonetheless fish do not prey on this organism, due to its efficient chemical defense. In a bioassay-guided structure elucidation, pteroenone 37 could be isolated and characterized as the main defensive principle of C. antarctica [82,83]. If embedded in alginate, this compound is a feeding-deterrent in nanomolar concentrations. This unusual metabolite is likely to be produced by C. antarctica itself and not accumulated from its food, since its major food sources did not contain any detectable quantities of 37. 

Fig. 5.5 (A) Alginate block copolymer structure with random sequences (B) divalent cations induced gelation of alginate (formation of egg-box structure).

Carrageenans and alginates present different conformations egg-box structure (alginates) and double helices (carrageenan) but both natural biopolymers are able to form gels and consequently, to control nanoparticle growth. 

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