D,L-lactide

Polymer—polymer iacompatibiHty encapsulation processes can be carried out ia aqueous or nonaqueous media, but thus far have primarily been carried out ia organic media. Core materials encapsulated tend to be polar soHds with a finite degree of water solubiHty. EthylceUulose historically has been the sheU material used. Biodegradable sheU materials such as poly(D,L-lactide) and lactide—glycoHde copolymers have received much attention. In these latter cases, the object has been to produce biodegradable capsules that carry proteias or polypeptides. Such capsules tend to be below 100 p.m ia diameter and are for oral or parenteral administration (9). 

Coordination numbers ranging from five to seven were observed, and they appeared to be controlled by the steric bulk of the supporting amidinate and coligands. Complexes 2-5 and 7 were found to be active catalysts for the pol3uneiization of D,L-lactide (e.g., with 2 and added benzyl alcohol, 1000 equiv of D,L-lactide were polymerized at room temperature in <1 h). The neutral complexes 2, 5, and 7 were more effective than the anionic complexes 3 and 4. ... 

Polymerization of D,L-lactide to polylactide was also achieved using monomeric tin(ll) amidinates (cf. Schemes 48 and and the mono... 

SCHEME 8.8 Synthesis of statistical poly(trimethylene carbonate-co-D,L-lactide) copolymers. 

Pego AP, Siebum SB, Luyn MJAV, et al. Preparation of degradable porous structures based on 1,3-trimethylene carbonate and D,L-lactide(co)polymers for heart tissue engineering. Tissue Eng, 2003, 9, 981 994. 

Pego AP, Luyn MJAV, Brouwer LA, et al. In vivo behaviour of poly (1,3-trimethylene carbonate) and copolymers of 1,3-trimethylene carbonate with D,L-lactide or e-caprolactone Degradation and tissue response. J Biomed Mater Res, 2003, 67A, 1044—1054. 

Bissery, M. C., Valeriote, F., and Thies, C., Fate and effect of CCNU-loaded microspheres made of poly(D,L) lactide (PLA) or poly B-hydroxybutyrate (PHB) in mice, Proc. Int. Symp. Control. Rel. Bioact. Mater.. 12. 181, 1985. 

Zhu, K. J., Xiangzhou, L., and Shilin, Y., Preparation and properties of D,L-lactide and ethylene oxide copolymer A modifying biodegradable polymeric material, J. Polym. Sei. Part C Polvm. Lett.. 24, 331-337, 1986. 

N Ammoury, H Fessi, JP Devissaguet, M Allix, M Plotkine, RG Boulu. Effect on cerebral blood flow of orally administered indomethacin-loaded poly (isobutylcyanoacrylate) and poly(d,l-lactide) nanocapsules. J Pharm Pharmacol 42 558-561, 1990. 

N Ammoury, H Fessi, JP Devissaguet, M Du-brasquet, S Benita. Jejunal absorption, pharmacological activity, and pharmacokinetic evaluation of indomethacin-loaded poly(d,l-lactide) and poly(-isobutyl-cyanoacrylate) nanocapsules in rats. Pharm Res 8 101-105, 1991. 

Free radical polymerization combined with anionic ring polymerization was employed for the synthesis of poly(N-vinylpyrrolidone)-fr-poly(D,L-lactide), PVP-fr-PDLLA, as shown in Scheme 49 [121]. The free radical polymerization of VP was conducted using 2,2/-azobis[2-methyl-M-(2-hydroxyethyl)propionamide] as the initiator, isopropyl alcohol and 2-... 

Jensen et al. reported the stereoselective polymerization of D,L-lactide with dibenzyloxidezinc(2,4,6-trimetylphe-nyimidazol-2-ylidene), which was synthesized as shown in Scheme 39.100 Surprisingly, a mixture of the heterocarbene and benzyl alcohol was a better catalyst for polylactide formation than the zinc complex, and unlike 50 the mixture produced heterotactically enriched polylactide. 

Lemoine D, Francois C, Kedzierewicz F et al (1996) Stability study of nanoparticles of poly (e-caprolactone), poly(D, L-lactide) and poly(D, L-lactide-co-glycolide). Biomaterials 17 2191-2197... 

Panyam J, Dali MM, Sahoo SK et al (2003) Polymer degradation and in vitro release of a model protein from poly(D, L-lactide-co-glycolide) nano- and microparticles. J Control Release 92 173-187... 

Waeckerle-Men Y, Allmen EU, Gander B et al (2006) Encapsulation of proteins and peptides into biodegradable poly(D, L-lactide-co-glycolide) microspheres prolongs and enhances antigen presentation by human dendritic cells. Vaccine 24 1847-1857... 

A subsequent study by Perez et al. (2001) investigated the use of poly (ethylene glycol)-(D,L-lactide) (PEG PLA) nanospheres for encapsulation... 

Singh, M., A. Singh, G.P. Talwar, Controlled Delivery of Diphtheria Toxoid Using Biodegradable Poly(D, L-Lactide) Microcapsules, Pharmaceutical Research. 8, 958, 1991. 

Panyam, J., Sahoo, S.K., Prabha, S., Bargar, T., Labhasetwar, V., Fluorescence and electron microscopy probes for cellular and tissue uptake of poly(D,L-lactide-co-glycolide) nanoparticles. Int J Pharm 262, 1-11 (2003). 

Yang DJ, Kuang LR, Li C, Kann Z, Wallace S (1994) Computed tomographic hver enhancement with poly(d,l-lactide)-microencapsulated contrast media. Invest Radiol 29 (Suppl 2) ... 

Besides the investigation of stereoisomers, the degradation of copolymers with E-caprolactone [24, 28, 29], 5-valerolactone [24, 28, 29], y-butyrolacton [30] and D,L-lactide [31] were also studied. The trends are found to be independent of the co-monomer. Co-monomer units within the polymer lead to an increase of degradation rate up to ten times that of natural PHB. The reason for this finding is the change of crystallinity within in the synthetic material, which could by proved by various DSC measurements of different copolymers and compositions. 

Gautier S, D Aloia V, Halleux O, Mazza M, Lecomte P, Jerome R (2003) Amphiphilic copolymers of e-caprolactone and y-substituted-e-caprolactone. Synthesis and functionalization of poly(D,L-lactide) nanoparticles. J Biomater Sci Polym Ed 114 63-85... 

Table 8 Polymerization of d,L-lactide with various amino acid Schiff base-metal complexes...

Earlier, ROP of glycolide and D,L-lactide through precipitation was carried out in nontoxic supercritical CO2 in the presence of SnOct2as initiator and copoly(ester) poly(D,L-lactide-co-glycolide) (PLGA), which can be easily separated from... 

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