Poly acid-based polymers

Uchegbu and coworkers have studied the complexation and delivery of DNA using a unique poly(amino acid)-based polymer vesicle. A polymer of either poly (L-lysine) or poly(L-omithine) was functionalized with methoxy-poly(ethylene glycol) (mPEG) and hydrophobic palmitic acid chains to synthesize an amphiphilic triblock of either mPEG-6-poly(L-lysine)-6-palmitoyl or mPEG-Z>-poly(L-omithine)-6-palmitoyl. Vesicles formed from these polymers were complexed with DNA and showed improved transfection in vitro over poly(amino acid) complexed with DNA or DNA alone [82]. 

A series of articles were published by Ennari et al. on MD simulation of transport processes in Poly(Ethylene Oxide) and sulfonic acid-based polymer electrolyte.136,137 The work was started by the determination of the parameters for the ions missing from the PCFF forcefield made by MSI (Molecular Simulations Inc.), to create a new forcefield, NJPCFF. In the models, the proton is represented as a hard ball with a positive charge. Zhou et al. used the similar approach to model Nation.138 The repeating unit of Nafion (Fig. 17) was optimized using ab initio VAMP scheme. The protons were modeled with hydronium ions. Three unit cell or molecular models were used for the MD simulation. The unit cell contains 5000 atoms 20 pendent side chains, and branched Nafion backbone created with the repeating unit. Their water uptakes or water contents were 3, 13, or 22 IEO/SO3, which correspond to the room temperature water uptakes at 50% relative humidity (RH), at 100% RH, and in liquid water respectively.18 The temperature was initially set at a value between 298.15 and 423.15 K under NVE ensemble with constant particle number, constant volume (1 bar), and constant energy. 

Analogous poly(itaconate)s polymers like poly(ditetrahydrofurfuryl methacrylate) have been also studied because there are at least two advantages in using ita-conate acid based polymers over methacrylate acid derivatives itaconic acid can be obtained through fermentation from renewable, non petrochemical sources and the toxicity of its derivatives is lower than for methacrylate derivatives [64,140],... 

Encapsulation and delivery of DNA has also been investigated with poly(amino acid) (poly(AA)) based polymer vesicles. Brown and coworkers synthesized an amphiphilic triblock copolymer from methoxy-poly(ethylene glycol) (mPEG), hydrophobic palmitic acid chains in block segments along a poly-L-lysine (PLL) or... 

Y. Liu, Q. Yu, and Y. Wu. More studies on the sulfonated poly(phenyl-ene oxide)+iniidazole bronsted acid-base polymer electrolyte membrane. J. Phys. Chem. Solids, 68(2) 201-205, February 2007. 

Poly(R-) and poly(S-P-malic acid)s were synthesized from the two optical isomers of malic acid and of aspartic acid. The family of malic acid based polymers includes also the alpha isomers, i.e. polymers where malic acid repeating rmits are linked through the alpha hydroxy acid part of the molecule. ... 

Tsuneizumi et al. [13] studied the chemical recycling of poly(lactic acid)-based polymer blends using environmentally benign catalysts, clay catalysts, and enzymes. Poly(L-lactic acid) (PLLA)-based polymer blends (e.g., PLLA/polyethylene [PE] and PLLA/poly(butylenes succinate) [PBS]) were degraded into repolymerizable oligomer. 

Amino acid-based polymers have been investigated as a potential source of valuable biomaterials for several decades. However, with the notable exception of poly(y-substituted glutamates), most amino acid-derived polymers exhibit problems with immunogenicity and poor mechanical properties for most biomedical applications. In order to overcome these limitations, Bourke and Kohn " devised a combinatorial strategy using amino acid monomers polymerized through non-amide... 

Cationic amino acid-based polymers possess limited transfection efficacies due to their high toxieities. To solve this problem. Pun and colleagues prepared poly(L-lysine) (PLL) and poly(hydroxypropyl methacrylate) (PHPMA)... 

Liu Y, Yu Q, Yuan J, Ma L, Wu Y. Bronsted acid-base polymer electrolyte membrane based on sulfonated poly(phenylene oxide) and imidazole. Eur Polym J 2006 42(9) 2199-203. 

From 1970, amino acids-based homo- and copolymers were studied for biomedical applications the idea was quite intuitive, because proteins are made of amino acids. However, initial studies showed that most poly(amino acids) could not be employed for biomedical applications because of immunogenicity problems and poor mechanical properties. Only a small number of poly(y-substituted glutamates) possess adequate characteristics to be interesting. In order to improve mechanical and physiological features of these materials, amino acids can be used as monomeric building blocks in polymers that do not have a backbone with the conventional structure which can be found in peptides. These materials are the so called non-peptide amino acids-based polymers or amino-acid-derived polymers with modified backbone , and can be divided into four main categories (Bourke and Kohn, 2003) ... 

The low heat deflection temperature of PLA limits its use for several application fields, such as in packaging materials and electronic components. The introduction of rigid building blocks [63] or cross-links [64] is known, for instance, to increase the glass transition temperature and/or heat resistance of lactic acid based polymers. The effect of different amounts of comonomers in the prepolymers on the Tg and mechanical properties of poly(ester-urethane)s is demonstrated in Table 3.2. The heat resistance of poly(ester-ure-thane)s can be improved by the copolymerization of lactic acid with D,L-mandehc acid. This broadening of the operating temperature range is of clear practical importance. The incorporation of other comonomers that impede rotation and make polymer chains less mobile also causes an increase in Tg, even if the same comonomers can depress the rate of poly condensation [50]. 

The ecotoxicological impact of lactic acid-based polymers was evaluated by biotests, i.e. by the Flash test, measuring the inhibition of light production of Vibrio fisheri, and by plant growth tests with cress, radish, and barley [16]. Poly(lactic acid)s, poly(esterurethane)s... 

Along this line, boronic acid-based polymer complexes are sensitive to glucose as a potential insulin delivery system, presumably due to the competitive binding of glucose to boronic acids, which disrupts the boronic acid-diol complex network within the polymer matrix (Scheme 13.5) [157]. In one study, the phenylboronic acid (PBA) moiety was attached to poly(M-vinyl-2-pyrrolidone) (NVP) to form poly(NVP-co-PBA)... 

By certain physical factors like thermal, ultraviolet irradiation, high pressure and other chemical parameters like organic solvents the helical pol5mers are easily denaturalized. A variety of helical polymers are synthesized, which include polyisocyanates, polyisocyanides, polychloral, polymethacrylates, polysilanes, polythiophenes, poly (p-phenylene)s, poly(l-methylpropargyl-ester)s, poly(phenylacetylene)s and poly (-unsaturated ketone) [18-24] (Fig. 1). Other polymers are whose optical activity is main chain or side chain chirality dependent e.g. amino-acid-based polymers are nontoxic, biocompatible and biodegradable. 

The antiviral properties of anionic polymers have recently received a lot of attention as agents to protect against infection with sexually transmitted diseases. Due to the cationic nature of most viruses, several anionic polymers are known to bind viruses. As early as the 1960s, researchers had studied the anti-viral properties of a variety of synthetic polymers [118]. However, not all anionic polymers inactivate viruses. Several classes of anionic polymers have been studied for their ability to inactivate the HIV virus. These polymers include poly(styrene-4-sulfonate), 2-naphthalenesulfonate-formaldehyde polymer, and acrylic acid-based polymers. Certain chemically modified natural polymers (i.e., semisynthetic) such as dextrin/dextran sulfates, cellulose sulfate, carrageenan sulfate, and cellulose acetate phthalate have also been investigated for this purpose. Of a number of such anionic polymers that have shown in-vitro and in vivo anti-HIV activity, a couple of polymeric drug candidates have proceeded to early stage human clinical trials for the evaluation of safety/tolerability [119]. While most of these have shown the desired tolerability and safety, further clinical trials are necessary to discern the therapeutic benefit and see if anionic polymers will be applicable as anti-HIV therapies. 

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