Enzymatic biodegradation

The yeast-mediated enzymatic biodegradation of azo dyes can be accomplished either by reductive reactions or by oxidative reactions. In general, reductive reactions led to cleavage of azo dyes into aromatic amines, which are further mineralized by yeasts. Enzymes putatively involved in this process are NADH-dependent reductases [24] and an azoreductase [16], which is dependent on the extracellular activity of a component of the plasma membrane redox system, identified as a ferric reductase [19]. Recently, significant increase in the activities of NADH-dependent reductase and azoreductase was observed in the cells of Trichosporon beigelii obtained at the end of the decolorization process [25]. 

The most widely used intestinal microbial strains used to test colon targeting and enzymatic biodegradation of the carrier, respectively, are microorganisms with azoreductases and different types of glycosidases. 

The strategy behind using such combinations is for the swelling agent to first facilitate slow dissolution of the methacrylate copolymer in the small intestine, and, second, in the colon to enhance the dissolution by enzymatic biodegradation. 

Lee and Wang [80] investigated the effects of lysine-based diisocyanate (LDI) as a coupling agent on the properties of biocomposites from PLA, poly (butylene succinate) (PBS) and bamboo fiber (BF). They observed that the tensile properties, water resistance, and interfacial adhesion of both PLA/BF and PBS/BF composites were improved by the addition of LDI, but thermal flow [81] was hindered due to cross-linking between polymer matrix and BF. Enzymatic biodegradability of... 

To determine the effect of the particle size on the biodegradation of Dynasan 114 SLN, stabilized with sodium cholate, a degradation-enhancing surfactant and poloxamer 407 (a surfactant that hinders the enzymatic biodegradation [11]) were used to produce SLN of different sizes (Table 6.2). Sodium cholate-stabihzed SLN are in the size range of 182 to 304 run and do not show any differences in their ) 2005 by CRC Press LLC... 

For polyCpropylene alkanedicarboxylate)s, the chanical hydrolysis and enzymatic biodegradation are shown in Fig. 18. The enzymatic degradation rates of these aliphatic polyesters are about 40-fold higher than the rates of the nonenzymatic hydrolysis. 

For aliphatic-aromatic PBS copolymers, the enzymatic biodegradation rate decreases with increasing aromatic comonomer content (Honda et al. 2003 Li et al. 2007), as indicated in Fig. 19. 

The great variety of applications of chitosan in the field of biomaterials is due to its excellent properties when interacting with the human body bioactivity, antimicrobial activity, immunostimulation, chemotactic action, enzymatic biodegradability, mucoadhesion and epithelial permeability which supports the adhesion and proliferation of different cell types [149]. 

All those commercial synthetic absorbable sutures fabricated from the gly-colide, lactide, e-caprolactone, p-dioxanone, and trimethylene carbonate building blocks can only be degraded via pure hydrolysis. Although it has been suggested that enzymes are involved, the issue is remains unresolved and controversial. There were no truly enzymatically biodegradable synthetic absorbable fibers on the market until the reported studies of amino add-based poly(ester amide)s (AA-PEA). 

Tsitlanadze G, Machaidze M, Kviria T, Katsarava R and Chu C C (2004b), In vitro enzymatic biodegradation of amino acid based poly(ester amide)s biomaterials ,/ Mater Sci Mater Med, 15,185-190. 

High GAE content results in higher cross-link density, reducing enzymatic biodegradation rate... 

There are two major classes of natural polymers used as scaffolds polypeptides and polysaccharides (Table 37.1, Figure 37.1). Natural polymers are typically biocompatible and enzymatically biodegradable. The main advantage for using natural polymers is that they contain bio-functional molecules that aid the attachment, proliferation, and differentiation of cells. However, disadvantages of natural polymers do exist. Depending upon the application, the previously mentioned enzymatic degradation may inhibit... 

The effect of co-PEA composition on enzymatic biodegradation was studied in enzyme phosphate buffer solution. Figure 2 summarizes lipase-catalyzed weight loss data from four different types of co-PEA films a) 4-Leu(6)o.75-Lys(Bz)o.25, b) 8-Leu(6)o.75-Lys(Bz)o.25, c) 4-Leu-(6)o.5-Phe(6)o.25-Lys(Bz)o.25, d) 8-Leu(6)o.5-Phe(6)o.25 Lys(Bz)o.25 There was virtually no weight loss in the PBS control during the same testing period. Several of these co-PEAs show close to zero order kinetics, a property important for sustained and controlled release of drugs. 

Khelfallah, N. S., Decher, G. and Mesini, P. J. (2006). Synthesis of a new PHEMA/ PEG enzymatically biodegradable hydrogel. Macromolecular Rapid Communications, 27,1004-1008. 

Van Dijk, M., Van Nostrum, C. E, Hennink, W.E.,Rijkers,D.T.S. and Liskamp,R. M. J. (2010). Synthesis and characterization of enzymatically biodegradable PEG and peptide-based hydrogels prepared by click chemistry. Biomacromolecules, 11,1608-1614. 

The present paper deals with enzymatic biodegradation of film chitosan coatings which can be used for protecting open wounds (burning, surgical ones) and the means of their modification for extending the service life. 

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