Dextran dialdehyde

The crosslinking of polymers in a binary membrane complex via covalent binding is a traditional method for improving the impact resistance of materials. Generally, high molecular crosslinkers have been successful (e.g., dextran dialdehyde... 

Reduced dextran dialdehydes. The reaction of dextran (D-OH) with sodium metaperiodate is a two step reaction leading to different kinds of aldehyde functions. Although the aldehyde content can not be precisely predicted from the amount of periodate added, by approximation 1.5 equivalents of periodate are required per dialdehyde structure. By varying the amount of periodate added to the polysaccharide dextran dialdehydes with variable degree of oxidation were obtained. In order to avoid interaction of the polyaldehyde (D-CH=0) with the dextranases the aldehyde groups were subsequently reduced by reaction with sodium borohydride ... 

Kobayashi, M. and Takatsu, K., Cross-linked stabilization of trypsin with dextran-dialdehyde, Biosci. Biotech. Biochem., 58 275-278, 1994. 

Schacht, E., Bogdanov, B., Van Den Bulcke, A., and De Rooze, N. (1997) Hydrogels Prepared by Cross-Linking of Gelatin with Dextran Dialdehyde. React. Fund Polym., 33, 109-116. 

Draye J P, Delaey B, Voorde A V D, Bulcke A V D, Rue B D, Schacht E (1998), In vitro and in vivo biocompatibility of dextran dialdehyde cross-linked gelatin hydrogel films , Biomaterials, 19, 1677-87. 

Iodine-assisted cleavage of the vicinal diol group of dextran has been investigated [77]. Dialdehyde starch (63) can... 

Periodate oxidation. Aldehyde groups can be easily introduced in most polysaccharides by reaction with sodium periodate. Vicinal diol structures give rise to dialdehydes. For dextran (I) having three adjacent hydroxyl groups in each non-branched anhydro glucopyranoside repeat unit the oxidation is a two step reaction ... 

Oxidized starch loses its ability to gel, thereby making low Tfi dispersions. Glucose dialdehyde is a glucose oxidation compound used to crosslink agarose (linear) and dextran (branched) for their performance as adsorbents. Oxidized celluloses are a substitute for glues manufactured from animal by-products. 

Dextran-spermine-based conjugates have been prepared via reductive amination between oxidised dextran and spermine [11]. Spermine, a naturally occurring linear polyamine, is involved in cellular metabolism and is a polycation at physiological pH. Dextran was initially oxidised with potassium periodate and the obtained dialdehyde derivative was then reacted under basic conditions with spermine. Dextran-spermine displayed particularly high transfection efficiency, which was attributed to the unique complexation properties between DNA and the grafted spermine moieties. Dextran-spermine and their derivatives have shown high transfection of p-DNA both in vitro and in vivo [12]. 

Preparations of pancreatic ribonuclease, ribonuclease from Actinomyces rimosus, and the nuclease from Serratia marcescens have been covalently bound to 4 3-hydroxyethylsulphonylanisole-, 4j3-hydroxyethylsulphonylaniline, and 3-Cl-2-hydroxypropyl derivatives of dextran and dialdehyde-dextran and to the 4-aminobenzyloxymethyl ester of dextran.The yield and thermal stability of the modified nucleases depends both on the amount and the character of the functional groups activating the polysaccharide. 

If the second reaction step is not much faster than the first one, the intermediate form will be present as well in the final oxidation product. Consequently less than two moles of periodate are required to produce one equivalent of dialdehydes. The ratio of the amount of both types of dialdehydes and depends upon the initial amount of periodate. This is clearly demonstrated in figure 3 which shows the fraction of intact glucose units and the fraction of both types of dialdehydes in partially oxidized dextran for varying reaction conditions. These results were obtained by measuring the periodate consumption and the formic acid formation for a set of oxidation experiments starting from varying amounts of periodate. 

The reaction product obtained by periodate activation of dextran is complex, not only because of the presence of different types of dialdehydes, but also because of the fact that these aldehydes are not present in free form but as hydrates or hemiacetals. 

Recendy, to simplify the reduction process, a series of polymers that can act as re-ductants to reduce noble metal ions at room temperature were used to synthesize metal/ metal oxide NC gels. These polymers contain poly(3,4-ethylenedioxythiophene) (Xiao et al., 2013), poly(ethylene oxide propylphosphonamidate) (Zhang et al., 2013), dextran (Ma et al., 2009), dialdehyde starch (Xia et al., 2012), and so on. 

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