Degradation polyvinyl alcohol

Recently, Brich and coworkers (40) reported the synthesis of lactide/glycolide polymers branched with different polyols. Polyvinyl-alcohol and dextran acetate were used to afford polymers exhibiting degradation profiles significantly different from that of linear poly-lactides. The biphasic release profile often observed with the linear polyesters was smoothened somewhat to a monophasic profile. Further, the overall degradation rate is accelerated. It was speculated that these polymers can potentially afford more uniform drug release kinetics. This potential has not yet been fully demonstrated. 

L Chen, SH Imam, SH Gordon, RV Greene. Starch polyvinyl alcohol crosslinked film—Performance and biodegradation. J Environ Polym Degradation 5 111-117, 1997. 

Secondary alcohol oxidases catalyze the oxidation of secondary alcohols to ketones using molecular oxygen as oxidant. A secondary alcohol oxidase from polyvinyl alcohol-degrading bacterium Pseudomonas vesicularis var. povalolyticus PH exhibited activity toward several... 

Polyvinyl alcohol is unique in being the only biodegradable carbon-carbon backbone polymer.(35,36) The degradation is oxidative, followed by hydrolytic cleavage, Suzuki claims acids and ketones as metabolites, and Watanabe acids and alcohols. This difference is shown below, schematically. 

Kawai F, Hu X (2009) Biochemistry of microbial polyvinyl alcohol degradation. Appl Microbiol Biotechnol 84 227-237... 

Russo M, O Sullivan C et al (2009) The anaerobic degradability of thermoplastic starch Polyvinyl alcohol blends Potential biodegradable food packaging materials. Bioresour Technol 100 1705-1710... 

Lim JG, Park DH (2001) Degradation of polyvinyl alcohol by Brevibacillus laterosporus. J Microbiol Biotechnol 11 928-933... 

Schonberger H, Baumann A, Keller W, Pogopetris P (1997) Study of microbial degradation of polyvinyl alcohol (PVA) in wastewater treatment plants. American Dyestuff Reporter August 1997 9-18. Available at http //www.p2pays.org/ref/02/01722.pdf. Last accessed 16 Aug 2011... 

E Kawagoshi Y, Eujita M (1998) Purification and properties of the polyvinyl alcohol-degrading enzyme 2,4-pentanedione hydrolase obtained from Pseudomonas vesicularis var. povalolyticus PH. World J Microbiol Biotechnoi 14 95-100... 

Shimao M, Onishi S, Kato N, Sakazawa C (1989) Pyrroloquinolme qumone-dependent cytochrome reduction in polyvinyl alcohol-degrading Pseudomonas sp. strain VM15C. Appl Environ Microbiol 55 275-278... 

Solid waste discharges from chemical plants can represent very large problems, especially from paper mills, plastics plants, and food processing plants. Some materials do not decompose in the environment, and can become burdens when they accumulate. Some polymers have backbones that degrade in nature, such as aliphatic polyesters and polyvinyl alcohols others do not, such as polyethylene and polystyrene. 

Work at the EPA Gulf Breeze Laboratory has demonstrated the potential usefulness of encapsulation in the bioremediation of PAHs. A model system has been developed in which a pure culture capable of degrading fluoranthene (strain EPA505) has been successfully encapsulated in polyurethane foam and polyvinyl alcohol (Baker et al., 1988). The capsules can be stored for several months at 4 °C with only minimal loss of viability. Upon addition of the capsules to moist soil, fluoranthene mineralization commenced in approximately the same way as observed when fresh bacterial cells were added to the soil. These results are shown in Figure 5.7a. Since the same inoculation size was used in all flasks during this experiment, the results suggest that the immobilization process does not significantly affect microbial activity. 

An example of a degradable matrix system is the pilocarpine-containing inserts formulated by Saettone et al. [148]. Pilocarpine nitrate and polyacrylic acid were incorporated into a matrix containing polyvinyl alcohol and two types of hydroxy-propyl methylcellulose. It was shown that all inserts significantly increased the pharmacological effect (miotic response) compared to a solution of pilocarpine nitrate. 

Polyvinyl alcohol is a vinyl polymer with a carbon-carbon backbone similar to other polymers such as polyethylene and polystyrene and is widely used as a water-soluble biodegradable polymer in the manufacture of delivery systems for fertilizers, pesticides and herbicides and is also used to manufacture containers and films. To date, only bacteria have been described as causing biodegradation of polyvinyl alcohols with some causing complete degradation of the polymer (see Shimao, 2001 for review). 

Vink [25] found that Fe+ and Cr ions slightly affected the course of oxidative degradation of (1) hydroxyethylcellulose, (2) methylcellulose (both frequently used as dry press binders), (3) polyoxyethylene, (4) polyvinyl alcohol, and (5) polymethacrylic acid (frequently used as steric stabilizers and binders for aqueous ceramic suspensions). 

Polyvinyl alcohol is stable when stored in a tightly sealed container in a cool, dry place. Aqueous solutions are stable in corrosion-resistant sealed containers. Preservatives may be added to the solution if extended storage is required. Polyvinyl alcohol undergoes slow degradation at 100°C and rapid degradation at 200°C it is stable on exposure to light. 

Some polymers, which do not form condensed complexes with plasmid DNA, have been reported to exhibit an enhancing effect on the transgene expression of naked plasmid DNA in skeletal muscle. Polyvinyl pyrrolidone and polyvinyl alcohol have been used to increase the extent and level of transgene expression following intramuscular injection of plasmid DNA.83 In addition, Hartikka et al.84 reported that a change of injection vehicle from saline or phosphate-buffered saline to 150 mM sodium phosphate buffer could enhance transgene expression by naked plasmid DNA in muscle due to inhibition of DNA degradation. 

To stabilize proteins against these degradative steps, excipients have proven to be quite effective. For instance, surfactants such as polysorbates, polyvinyl alcohol and (hpamitoyl phosphatidyl choline have been used to prevent the adsorption of proteins at the air-hquid interface during spray drying [8, 9],... 

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