Poly degradation products

An example is poly(bis(p-carboxyphenoxy)propane) (PCPP) which has been prepared as a copolymer with various levels of sebacic anhydride (SA). Injection molded samples of poly (anhydride) / dmg mixtures display 2ero-order kinetics in both polymer erosion and dmg release. Degradation of these polymers simply releases the dicarboxyhc acid monomers (54). Preliminary toxicological evaluations showed that the polymers and degradation products had acceptable biocompatibiUty and did not exhibit cytotoxicity or mutagenicity (55). 

A series of poly(ester-urethane) urea triblock copolymers have been synthesized and characterized by Wagner et al/ using PCL, polyethylene glycol, and 1,4 diisocyanatobutane with either lysine ethyl ester or putrescine, as the chain extender. These materials have shown the elongation at break from 325% to 560% and tensile strengths from 8 to 20 MPa. Degradation products of this kind of materials did not show any toxicity on cells. 

The property of thermal, reversible gelation is obtained by the addition of water-soluble proteins and protein degradation products to an aqueous solution of poly (vinyl alcohol) 2). Protein products such as albumin, gelatin, glue, a-amino acids, and their condensation products—diketopiperazines—may be used. A typical formulation for the preparation of a thermally reversible gel is ... 

Biodegradable poly(phosphoester-urethanes) containing bisglycophosphite as the chain extender were synthesized. Methylene bis-4-phenyl isocyanate (MDI) and toluene diisocyanate (TDI) were initially used as diisocyanates. Since there was a concern that the degradation products could be toxic, the ethyl 2,6-diisocyanatohexanoate (LDI) was synthesized and replaced the MDI (or TDI). The hydrolytic stability and solubility of these polymers were tested. Preliminary release studies of 5-fluorouracil from MDI based poly(phosphoester-urethane) and methotrexate from LDI based poly(phosphoester-urethane) are also reported. 

Urethane hydrolyzes into an amine, an alcohol, and carbon dioxide. So the possible degradation products of a poly(phosphoester-urethane) are diamines, diols, phosphates, carbon dioxide, and even ureas. Urea is possible because the isocyanate is extremely sensitive to moisture, which would convert the isocyanate to an amino group. One is therefore bound to have traces of diamine in the polymerization that leads to a urea bond in the backbone. We think the cytotoxicity seen in the macrophage functional assay comes from the TDI structure. 

In a pyrogram of Bisphenol A poly(formal) (6), the peak products are identified as a-methylstyrene, phenol, 4-hydroxy-a-methylstyrene, and isopropyl phenol by Py-GC/MS. These products are identical with the degradation products from Bisphenol A. In addition to the decomposition products of Bisphenol A, 4-isopropenyl anisole is also identified as a product. The pyrograms of Bisphenol AF poly(formal) (7) contain only two major species, pentafluoroisopropenyl benzene (product T) and pentafluoroisopropenyl anisole (product 2 ). They correspond to a-methylstyrene, 4-hydroxy-amethylstyrene from Bisphenol A poly(formal) (6) and are produced by the cleavage of phenylene-oxy bonds and oxy-methylene bonds according to (Scheme 6). 

Matrix-Assisted Laser Desorption/lonization Time-of-liight Mass Spectrometry (MALDI-TOF MS, PerSeptive Biosystems Voyager-DE STR) was used to characterize the molecular weight distribution and the number average molecular weight (M ) of the poly(methacrylic acid) (PMAA) degradation products as described elsewhere [25]. 

Figure 6 MALDI-TOF distribution of PMAA chains as a function of molecular weight for the degradation products of a disk of poly(MSA) polymerized with 100 mW/cm ultraviolet light.

The enzyme catalyzing the transfer of D-apiose from UDP-apiose to 4, 5-dihydroxyflavon-7-yl /3-D-glucopyranoside is commonly called apiin synthetase.7 Activity is measured by the formation of [14C]apiin from UDP-[U-14C]apiose. Apiin synthetase can be measured by the rapid separation and isolation, by poly(ethylenimine)-paper chromatography, of a product of the reaction, namely, [14C] apiin, from UDP-D-[U-14C]xylose and degradation products of UDP-[U-14C]apiose.31 There are reports of the isolation and purification of apiin synthetase from parsley leaves,31 from cell-suspension cultures of parsley,121 and from foxglove (Digitalis purpurea).31 Apiin synthetase isolated from parsley does not require metal ions, NAD+, or other cofactors, and is soluble. It is inhibited by several heavy metals, but not by tetra-N-... 

Leibowitz and Silmann [26] have nitrated the degradation products of poly-amylose, namely di-, tri-, and tetra-amylose . Following in principle the nitration method introduced by Will and Lenze, Leibowitz and Silmann obtained a series of compounds, which they named ... 

Poly(vmyl alcohol) is one of the few truly biodegradable synthetic polymers the degradation products are watei and carbon dioxide. At least 55 species or varieties of microorganisms have been shown to degrade or participate in the degradation of PVA. 

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