Amine Alginates

Fig. 1. Capsule permeability as measured by the inverse GPC method. Capsules were made from 1.25% A-carrageenan (Fluka) and 0.02% carboxymethylcellulose (Aqualon) in 0.9% sodium chloride (core polymers) and 2% polydimethylamine-co-epichlorohydrin modified, quater-nized (Scientific Polymer Products) and a quaternary amine (Agefloc B50, CPS) in PBS (receiving bath) using a 3 min reaction time. The capsules were subsequently washed with PBS, coated for 15 min with 0.1% LV alginate (Kelco) and again washed in PBS. Two molecular size dex-trans were used to probe the capsule permeability. 170 kD dextran is almost totally excluded while the lower molar mass polymers permeated the membrane to varying extents...

Figure 22.11. Cellulose is a structural and rather chemically inert component of terrestrial plants. Alginic acid is synthesized by marine algae and has medicinal properties. Some polysaccharides contain nitrogen in the form of amino sugars. The primary example of this is chitin, which composes the exoskeletons of Crustacea. An amino sugar contains an amine in place of a hydroxyl group. In other polysaccharides, sugars combine with lipids and proteins. These form glycoUpids and glycoproteins, respectively.

The hemocompatibility of poly(amido-amine) polyelectrolyte complexes was recently studied by Xi, Zhang and coworkers [499, 500]. The poly(amido-amine) was based on piperazine and methylene bisacrylamide, and the polyelectrolyte complexes were obtained from the reaction of poly(amido-amine) with alginic acid, carboxymethyl cellulose or poly(methacrylic acid). Complexes of polyamido-amine and alginic acid with a 1 2 ratio gave the best hemocompatibility. Finally, the blood compatibility of polyelectrolyte complexes based on anionic and cationic cellulose derivatives were studied by Ito et al. [338], In vivo, good blood compatibility of complexes formed from quaternary hy-droxyethyl cellulose reacted with carboxymethyl cellulose and cellulose sulfate was observed. 

In this case, unilamellar vesicles with a large capture volume were prepared by the reverse phase evaporation technique and alginate was used to microencapsulate the liposome s. The alginate spheres were double coated, first with poly-L-lysine and then with polyvinyl amine (Wheatley and Langer in press). 

Carboxylic acid-containing polysaccharides can be easily functionalized by reactions such as esterification, amination, or amidation. Industrial esterification of polyuronides, including alginic acid (O Chap. 6.4), in aqueous medium can be easily accomplished by reaction with ethylene, propylene, butylene, andpentylene oxides in 50-80% yield [123]. 

Amination can be achieved by reductive amination of carboxyl groups using sodium cyano-borohydride [124]. By this method, 2-amino-2-deoxy functionalized amylose and cellulose have been produced. Reductive amination can also be applied to the synthesis of other amino derivatives of various oxidized polysaccharides such us xanthan [125] or alginic acid and galactomannans [126]. 

Fig, 5,3 Possible interactions between butyl amine and pectin or alginate [6,111... 

In the particular case of polysaccharides, this reaction has been used for the modification of several types of biopolymers with different applications [28, 29]. As an example, a monoaldehyde derivative of P CD (2) was prepared from the hydrolysis of product 1 and then grafted, by a reductive amination-type reaction, onto an alginate derivative selectively modified with adipic dihydrazide (alg-ADH) (Scheme 7.5). The new polymeric materials obtained, alg-ADH intermediate and jS-CD-grafted alginate were fully characterized in terms of chemical integrity and purity by high-resolution NMR spectroscopy [30]. 

The Ugi reaction is a multi-component organic chemistry reaction (Scheme 7.12), which includes the participation of either a ketone or an aldehyde, an amine, an isocyanide, and a carboxylic acid to form a bis-amide [50]. The particular case shown in Scheme 7.12 corresponds to the study carried out by Buet al. [51]. First, the imine formation is carried out by the reaction between the aldehyde compounds and the amine. Then, the carbon atom of the synthesized imine is attacked by the nucleophilic carbon atom of the isocianide, which yields an adduct as reaction product. In other pathway, the oxygen atom of a carboxylic acid is added to the previous product, and a new adduct is obtained. After an internal rearrangement of the latter molecular structure, a diamide compound is obtained. It is known that for a successful reaction a pH of 3.6 should be used in the reaction media [52]. This important reaction has been often used to prepare hydrophobically modified alginates [52,53]. 

Propylene glycol alginate Propyiene glycol laurate (N-Pyrrolidonepropyl) methylsiloxane-dimethylsiloxane copolymer Rapeseed amine Selachyl aicohoi... 

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