Alginate co-polymers

Chitin-alginate co-polymer Water-soluble chitin-alginate-PEI-DNA nanoparticles Nonwoven fibrous scaffold vehicle for DNA delivery Matrix capable of delivering genes to direct and support cellular development in tissue engineering... 

Polymer grafting can be used to alter chemical and physical properties of a homopolymer. For example, Sawhney and Hubbell [18] grafted polyethyleneoxide to poly L-lysine to enhance biocompatibility of polylysine and improve the polylysine-alginate capsules. Stevenson and Sefton [19] modified alginate by grafting it with hydroxyalkyl methacrylate, again to improve the biocompatibility and to allow for polymerization by means of y-irradiation. Covalently modified (co)-polymers have not been evaluated in this study. 

Alginates are linear co-polymers of randomly arranged P-D 1,4 mannuronic acid (M) and a-L 1,4 guluronic acid (G) blocks as represented in Fig. 5.3. Its chemical structure is similar to that of cellulose except that it has a carboxyUc group on the C5 position instead of a methylol group in the case of cellulose. 

Protein isolation with affinity precipitation has been discussed in detail by Mattiasson and co-workers (see, e.g. Galaev and Mattiassion, 1997) and they have provided an exhaustive tabulation. Polymers varied from alginate.s/chitosan to dextran to NIPAM. Examples of the used proteins are from trypsin, p-glucosidase, xylanase, alkaline protease, etc. It is remarkable that affinity precipitation can sometimes give results comparable to affinity chromatography. 

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...

HV Alginate 2% Spermine/1% Poly-methylene-co-guanidine T Smooth, Mosaic Membrane (Polymer Incompatibility ) 7/7... 

In other applications the pattern of evolution of styrene, butadiene and acrylonitrile as a function of temperature has provided a unique way for classifying different types of ABS. The loss of the antioxidant butylated hydroxytoluene (BHT) was also detected by MS preceding EVA copolymer degradation [165] BHT was identified at a concentration level of 20 ppm. Lehrle and co-workers [52] have described a successful controlled release system for the stabilisation of rubber by encapsulating efficient but rather mobile antioxidants to prevent loss from the host polymer. The performance of the controlled-release of the antioxidant BHT from alginate matrix particles was studied by means of DSC, TG and TG-MS. Polyisoprene rubber is more resistant to oxidation when protected in this way than by the equivalent concentration of unencapsulated antioxidant. 

A slightly different approach is to deliver the active drug in a dry powder carrier system, for example microcrystalline cellulose, hydroxyethyl starch, cross-linked dextran, microcrystalline chitosan, carbomer, pectin, or alginic acid. The polymer absorbs water upon contact with the nasal mucosa and swells to become a viscous gel, often demonstrating bioadhesive properties. Such systems can remain in the nasal cavity for as long as six hours. For example, the bioavailability in rats of the somatostatin analogue, octreotide, was shown to be enhanced by the co-administration of alginic acid and cross-linked dextran as dry powders. 

Research on nasal powder drug delivery has employed polymers such as starch, dextrans, polyacrylic acid derivatives (e.g., carbopol, polycarbophil), cellulose derivatives (microcrystalline cellulose, semicrystalline cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose), chitosan, sodium alginate, hyaluronans, and polyanhydrides such as poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA). Many of these polymers have already been used as excipients in pharmaceutical formulations and are often referred to as first-generation bioadhesives [38-45], In nasal dry powder a single bioadhesive polymer or a... 

Abbreviations ACP, cross-linked polysaccharide of hyaluronic acid ALAFF, polymer of an ester of alginic acid CBZ, carbamazepine PEG, polyethylene glycol DCM, dichloromethane DMF, dimethylformamide DMSO, dimethyl sulfoxide NMP, A/-methylpyrrolidone P-HBA, p-hydroxybenzoic acid HYAFF-1, hyaluronic acid benzylic ester PEG-PLA, poly(ethylene glycol)-poly(L-lactide) PLGA, poly(lactic-co-glycolide) acid. 

Immobilization can be achieved by adsorption or covalent fixation of the biocatalyst to a solid support (e.g. surface-modified polymer or glass beads), by entrapment or by encapsulation in gel beads (e.g., agarose, polyacrylamide, alginate, etc.). Hundreds of immobilization methods have been described and reviewed in the literature [83-89], but only a limited set of methods has found real technical applications. The first large-scale applications of immobilized enzymes were established for the enantioseparation of D- and L-amino acids by Chib-ata, Tosa and co-workers at Tanabe Seiyaku Company. The Japanese achievements in the large-scale application of immobilized systems are very well documented in an excellent multi-author publication edited by Tanaka, Tosa and Kobayashi [90] (see also section 7). Some enzyme suppliers sell important industrial enzymes not only in the free form (solution or powder) but also immobilized on solid supports. 

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