Polyacryl dextrans

A number of additional examples of protein delivery via polysaccharides are available in the scientific and patent literature. Edman et al. (1980) have demonstrated release of carbonic anhydrase, catalase, human serum albumin, and immunoglobulin G from cross-linked biodegradable polyacryl dextrans having molecular weights ranging from 10,000 to 2,000,000. Thermal stability of carbonic anhydrase was found to be enhanced via entrapment in microspheres of the above polymer. Schroder (1984) has shown that... 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

The support can be cellulose, agarose, dextran, silica, polyacrylate, polyvinyl, or polystyrene, among other resins. The most suitable matrix for a given application is often selected based on data provided by the manufacturers. 

Earlier pulse radiolysis investigations were devoted to the radiation effects of the polymers dissolved in water. The rate constants of the reactions of OH radicals with polyethylene oxide) [75, 76], polyvinylpyrolidone [75], dextran [75], and sodium polyacrylate [77] have been measured as functions of the chainlength and the polymer concentrations. The rate constant expressed in polymer unit (mol -1 dm3 s- M increased more slowly with increasing chainlength than would be expected if the reactivity of the CH2 and CH groups were additive. The reaction between small molecules and the polymer radicals produced by the reaction of OH radical with polyethylene oxide) has also been demonstrated [78]. 

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... 

Study on the rapid transport of a polymer in dextran solutions, first observed by Preston et al., is extended into two directions. They arc (1) enhancement effect on the transport rate of polyvinylpyrrolidone (PVP) by the addition of a simple salt, and (2) extension to the transport of linear polyelectrolytes. The enhancement effect was observed on the structured flow as well as on the transport rate. The enhancement effect was correlated with the densities of the solutions in the lower compartment of the diffusion cell. The correlation was improved when the rate was corrected for the differences in viscosities. We have found that effects of charges on the polymers favor the rapid transport of polyacrylates (PA) and sodium hyaluronate. Counterion condensation was manifested in the transport rate of PA. Transport rates of several salts of PA in the absence of added salt increased linearly with their partial specific volumes in water. 

We have observed rapid transport of polyacrylate (PA) and hyaluronate (HA) in dextran solution matrix, which will be the first extension to linear polyelectrolytes. The whole transport process did not follow the flow rcgime(linear in t) nor diffusion(linear in t ) but a combination of the two, when ionic strengths were not high enough. In the media of low ionic strengths, diffusion of linear polyelectrolytes is very rapid due to the effect of counterion diffusion. We sometimes observed structured flows under a situation that transport rate followed diffusion law. This behavior was more clearly observed on HA than PA. Effect of charges favored the rapid transport of both polyclcctrolytcs, since (a)... 

Figure 1. Effect of the counterion species on the transport rate of polyacrylates in dextran solutions without added salt.

Fig. 11 Scheme of layer-by-layer assembly of polyelectrolytes on activated porous supporting membrane. The separation layer is obtained upon multiple repetition of steps A and B. In reality, pore diameters are 20 to 200 nm, polymer chains are less ordered and partially overlapping. Polyelectrolytes PVA, poly(vinylamine) PAH, poly(allylamine hydrochloride) PEP, polyethyleneimine (branched), P4VP, poly(4-vinylpyridine) PDADMA, poly(diallyldimethylammonium chloride) PVS, poly(vinylsulfate) PVSu, poly(vinylsulfonate) PSS, poly(styrenesulfonate) PAA, polyacrylic acid DEX, dextran sulfate (from Ref. [70])... 

Some polymers can be used as accelerators of nucleic acid hybridization. They sometimes produce background staining and are only recommended when the hybridization rate is low (small amounts of probe or target). Dextran sulfate is often used as an accelerator but polyethylene glycol (PEG 6000) and sodium polyacrylate have been shown to be valuable alternatives. These polymers probably act by exclusion of probe molecules from the volume occupied by the hydrated polymer which results in an effective increase in the probe concentration (Wetmur, 1975). The optimal probe concentration in membrane hybridization is considered to be about 10 cpm of probe/ml (1-10 ng/ml), but Amasino (1986) found a 2- to 10-fold reduction in the probe concentration to be optimal when 10% PEG was included (note that these effects may depend on the specific activity of the probe). These polymers do not act in a similar way and have their own characteristics. 

Nylon Polyalkylene Polystyrene Polyacrylates Polyacrylamide Polyethylene Polypropylene Polyvinyl alcohol Polyvinylacetate Polyvinylchloride Polyethylene glycol Polyester Polycarbonate Polyurethane Polysiloxane Phenol-formaldehyde Cellulose Starch Agarose Dextran Chitin Polyalginate Carrageenan Sand Pumice Metal oxides Diatomaceous earth Clays... 

Other hydrophihc polymers have been conceived as alternatives to dextran [6]. For example, polyvinyl alcohol and polyacryl acid derivatives are feasible and graft combinations thereof have been shown to be applicable to SPR detection [14]. Poly-L-lysine has become popular for DNA microarray coatings, due to its highly positive charge. It has also been attached to SAM-derivatized gold surfaces for subsequent modification with thiol reactive groups [15]. 

Entrapment Agar, dextrane, alginate, carrageenan, collagen, polyacrylate, polysiloxane, polyvinylalcohol, polyethyleneglycol Calcium phosphate gel... 

Common matrix Cellulose, dextran, agarose, polyacrylate. Silica, resins... 

As for polymer materials used for encapsulation of some low molecular weight drugs, such as cytostatics, antibiotics, etc., which are more stable compared with animal cells or biopolymers (DNA, proteins, peptides, etc.), the list of polymer materials used for their encapsulation is more extended. It includes a series of synthetic polymers as well as their copolymers with namral polymers. We could mention polyacrylates, for example, polyaUcylcyanoacrylates [11], polyester-poly(ethylene glycol) [12], poly(epsilon-caprolactone) [13], polyethylenimine-dextran sulfate [14], dextran-HEMA (hydroxy-ethyl-methacrylate) [15]. 

Drag reduction is shown by polysaccharides, which are linear in nature. Highly branched materials such as gum arabic and dextran do not seem to reduce drag (17). Polyelectrolytes, such as partially hydrolyzed polyacrylamide (64,106), polyacrylic acid (118), acrylamide sodium acrylate copolymer (119), and sodium alginate (120), show higher drag reduction when the chain is extended or there is increment in coil dimensions. The coil expansion takes place because of coulom-bian repulsion and solvent steric hindrance of side group and main chain (119). 

Kirkland and co-workers have used this technique to determine the MWD of water-soluble polymers including polyethylene oxide in the 10 -2 x 10 molecular weight range, including sodium PS sulfates and dextrans [238]. Also, they applied the techniques using Mark-Houwink constants to PS, polyisoprene, poly-a-methylstyrene, polyacrylates, polyvinyl pyrrolidone, and PVC [238]. 

Polyacrylamide (PAA) and branched copolymer dextran-graft-polyacryl-amide (D-g-PAA) in anionic form were used as polymer matrices for in situ synthesis of Ag sols. Synthesis, characterization, and alkaline hydro-... 

Probes in small-M polymer solutions generally show Stokes-Einsteinian behavior with r]p, r], including 160 nm spheres(16) in 101 145 kDa PMMArCHCls for rj/rjs up to 10, 20, and 230 nm probes in aqueous 20 kDa dextran(12), and 20-1500 nm spheres in aqueous 50 kDa polyacrylic acid(lO). On the other hand, 49 and 80 nm probes in aqueous 90 kDa poly-L-lysine show small c-independent deviations from Stokes-Einsteinian behavior(14). Stokes-Einsteinian behavior is also found in some large-M systems. Onyenemezu, et al.(l9) find Stokes-Einsteinian behavior within experimental accuracy for 1100 kDa polystyrene solutions having rj/rjs as large as 100. Turner and Hallett(l) and Phillies, et a/. (12) reveal 1... 

Over the last years, there has been a growing interest in PECs based on natural and synthetic polymers. Chitosan is a natural polyaminosaccharide and a weak base. Its PECs with different natural and synthetic polyacids such as, carboxy-methylcellulose [29, 30], alginic acid [23], poly (acrylic acid) [31] are known. Besides alginate, carboxymethylcellulose, carrageenan, and dextran sulfate are the most extensively studied polysaccharides used in the formation of polyelectrolyte complexes [32, 33]. Some synthetic polyelectrolytes, like poly(l-lysine) and polyacrylates, have been used to make complexes with these polysaccharides [34]. In the above mentioned literature one can find different examples of PEC as well as various methods of forming them. 

---