Metal alginates

NMR was us to follow any changes in the al c acid as metal ions were added. From the data acquired, there are two aspects of bmding that can be discussed. The first is GG preference, the preference each metal has for one block type over another. The second is extent of binding, an indicator of the strength of the metal-alginate interaction, which is roughly analogous to stability constant. 

Figure 4. Ionic radius versus normalized peak intensity for divalent metal-alginates at 8% metal loading. GG blocks MM blocks...

Other properties of algin reported include conductivity (252 253), contact angles of various solvents on different metal alginate films 175), depolymerization rates for alginic acid in various acids (251, 25U, 255), a pK of 2.95 for the dissociation constant of alginic acid in normal potassium chloride solution (208), absorption spectra of algin (202), and properties determined in connection with molecular weight studies, such as sedimentation and diffusion velocity and partial specific volumes (209),... 

Pathak TS, Kim JS, Lee S-J et al (2008) Preparation of alginic acid and metal alginate from algae and their comparative study. J Polym Environ 16 198-204... 

Agulhon P, Robitzer M, Habas JP, Quignard F (2014) Influence of both cation and alginate nature on the rheological behavior of transition metal alginate gels. Carbohydr Polym 112 525-531... 

SEM investigation...Film form metal alginate----In a typical experi-... 

Figure 1. The network structure of bead metal alginate(sample 1).

The structural feature of the surface of metal alginate is the fiber network arranged regularly and closely, but that of the fractured surface is the large and spacious network having round cages or channels... 

Figure 3 shows the porous structure of a metal alginate. According to the report by Simionescu et al helicoidal portions of alginate chain will be made up of mannuronic acid under hydrochloric acid. In Figure 3 it is clearly observed that under the acid metal alginate fiber net takes the rounded, buckled and twisted form as much as possible and finally changes to a porous cluster form. Sample 4=M-rich is the precipitate at pH 1.5 adjusted with HCl. 

Iodine-metal alginate compound... Sodium alginate reacts with iodine and under acid gives a blue stained adduct like a starch-iodine inclusion complex. In this paper results for film form metal alginate are presented. The effect of pH on the formation of a blue stained adduct is shown in Figure 4A. At about pH 1 the formation reaches the maximum. The amount of the adduct shows an increase with iodine concentration and... 

X-ray fiber diffraction data of film form metal alginate showed broad peaks corresponding to around 7.2A, 8.7A. The characteristic fiber peak observed in the blue stained film prepared at pH 1 corresponds to 3.13A. This value is similar to 3.06A for I-I distance of iodine packed in helical cylinder of starch-iodine inclusion complex. 

Cholesterol...The reduction of cholesterol in acetic acid by increasing the amount of metal alginate beads is clearly seen in Figure... 

A. Figure 6B also shows the effect of Cd-alg. or Ca-alg. on cholesterol concentration in acetic acid. The addition of metal alginate... 

Figure 6. The effect of metal alginate on cholesterol in acetic acid.

A First step beads were suspended in 30ml of acetic acid containing 5mg of cholesterol for 24hr at 30. B Metal alginate beads formed from 40mg of Na-alg. were suspended in 30ml of acetic acid containing cholesterol... 

In the process of precipitation, the polyvalent metal alginate tends to become aligned when extruded through orifices and can be obtained in the form of fibers. If the precipitated alginate is not subjected to extrusion, the polyvalent metal alginate precipitate forms a gel, in which a large amount of water is held in the insoluble precipitate (hydrocolloid gel). 

Abstract. The binding properties of granular alginic acid(H-alg.) and chitin to iodine, bromine, cadmium ion, calcium ion and cholesterol were investigated. Chitin-iodine and chitin-bromine compounds closely resemble those of H-alg. The amount of iodine included by these polysaccharides increased with a decrease in the concentration of potassium iodide (KI). The number of sugar residues bound to one iodine molecule extrapolated to 0 g of KI was around 6.0 for H-alg. and 6.4 for chitin. These saccharides, which do not form a gel in water, were found to also absorb KI and radioactive iodide or iodine in aqueous solution. H-alg. did not show as much affinity to cadmium ion and calcium ion and cholesterol in iso-propyl alcohol as metal-alginates. 

The metal alginate fibre is very sensitive to acid. Electron microscopic evidence [10] indicated that under acid condition even on treatment with 2% osmic acid solu-... 

Cholesterol... None of chitin was obtained pure, so the sample of chitin obtained from carapace was positive to the cholesterol E-Test and the extinction to standard cholesterol solution increased with an increase in the amount of chitin, but any reduction of cholesterol by chitin was not observed at all. In the previous experiment the removal of cholesterol from acetic acid solution by the addition of metal alginate beads was observed. Such reduction of cholesterol from iso-propyl alcohol by the addition of metal alginate beads (unpublished), H-alg. or chitin is not observed in this experiment, so it indicates that the removal of cholesterol from the acidic solution depends on the shrinkage of the metal alginate beads, but not on the fiber chain packing. 

Papageorgiou, S.K., Kouvelos, E.P., Fawas, E.P., Sapalidis, A.A., Romanos, G.E., and Katsaros, F.K. (2010) Metal-carboxylate interactions in metal-alginate complexes studied with FTIR spectroscopy. Carbohydr. Res., 245, 469-473. 

---