. S. Langer, New methods of drug delivery, Science, vol.249, issue.4976, pp.1527-1532, 1990.
DOI : 10.1126/science.2218494

S. Langer and N. A. Peppas, Present and future applications of biomaterials in controlled drug delivery systems, Biomaterials, vol.2, issue.4, pp.201-214, 1981.
DOI : 10.1016/0142-9612(81)90059-4

R. Gombotz and D. K. Pettit, Biodegradable Polymers for Protein and Peptide Drug Delivery, Bioconjugate Chemistry, vol.6, issue.4, pp.332-351, 1995.
DOI : 10.1021/bc00034a002

K. Kwong, S. Chou, A. M. Sum, M. V. Sefton, and M. F. Gousen, In vitro and in vivo release of insulin from poly(lactic acid) microbeads and pellets, Journal of Controlled Release, vol.4, issue.1, pp.47-62, 1986.
DOI : 10.1016/0168-3659(86)90033-7

Y. Gref, M. T. Minamitake, V. Peracchia, V. Trubetskoy, R. Torchilin et al., Biodegradable long-circulating polymeric nanospheres, Science, vol.263, issue.5153, pp.1600-1603, 1994.
DOI : 10.1126/science.8128245

K. J. Jie and . Zhu, Preparation, Characterization and Biodegradable Characteristics of Poly(D,L-lactide-co-1,3-trimethylene carbonate), Polymer International, vol.42, issue.4, pp.373-379, 1997.
DOI : 10.1002/(SICI)1097-0126(199704)42:4<373::AID-PI722>3.0.CO;2-U

Y. Li, R. Zhang, W. Yan, M. Jia, X. Yuan et al., Influence of process parameters on the protein stability encapsulated in poly-dl-lactide???poly(ethylene glycol) microspheres, Journal of Controlled Release, vol.68, issue.1, pp.41-52, 2000.
DOI : 10.1016/S0168-3659(00)00235-2

W. Lim and T. G. Park, Stereocomplex formation between enantiomeric PLA-PEG-PLA triblock copolymers: Characterization and use as protein-delivery microparticulate carriers, Journal of Applied Polymer Science, vol.39, issue.13, pp.1615-1623, 2000.
DOI : 10.1002/(SICI)1097-4628(20000328)75:13<1615::AID-APP7>3.0.CO;2-L

Y. Cho, C. Kim, J. Lee, and J. Park, Synthesis and characterization of poly(ethylene glycol) grafted poly(L-lactide), Macromolecular Rapid Communications, vol.20, issue.11, pp.598-601, 1999.
DOI : 10.1002/(SICI)1521-3927(19991101)20:11<598::AID-MARC598>3.0.CO;2-1

A. Kugo, T. Ohji, J. Uno, and . Nishino, Synthesis and Conformations of A-B-A Tri-Block Copolymers with Hydrophobic Poly(??-benzyl l-glutamate) and Hydrophilic Poly(ethylene oxide), Polymer Journal, vol.252, issue.4, pp.375-381, 1987.
DOI : 10.1002/jbm.820040306

K. Cammas and . Kataoka, Functional poly[(ethylene oxide)-co-(??-benzyl-L-aspartate)] polymeric micelles: block copolymer synthesis and micelles formation, Macromolecular Chemistry and Physics, vol.196, issue.6, pp.1899-1905, 1995.
DOI : 10.1002/macp.1995.021960609

M. Kwon, M. Naito, T. Yokoyama, Y. Okano, K. Sakurai et al., Micelles based on AB block copolymers of poly(ethylene oxide) and poly(.beta.-benzyl L-aspartate), Langmuir, vol.9, issue.4, pp.945-949, 1993.
DOI : 10.1021/la00028a012

K. Harada and . Katoka, Novel Polyion Complex Micelles Entrapping Enzyme Molecules in the Core:?? Preparation of Narrowly-Distributed Micelles from Lysozyme and Poly(ethylene glycol)???Poly(aspartic acid) Block Copolymer in Aqueous Medium, Macromolecules, vol.31, issue.2, pp.288-294, 1998.
DOI : 10.1021/ma971277v

S. Yokoyama, R. Fukushima, K. Ueharo, K. Okamoto, Y. Kataoka et al., Characterization of physical entrapment and chemical conjugation of adriamycin in polymeric micelles and their design for in vivo delivery to a solid tumor, Journal of Controlled Release, vol.50, issue.1-3, pp.79-92, 1998.
DOI : 10.1016/S0168-3659(97)00115-6

P. Mc-gee, M. Singh, X. M. Li, H. Diu, and D. T. O-'hagan, The encapsulation of a model protein in poly (D, L lactide-co-glycolide) microparticles of various sizes: an evaluation of process reproducibility, Journal of Microencapsulation, vol.16, issue.2, pp.197-210, 1997.
DOI : 10.1016/0264-410X(91)90295-H

X. Song, H. F. Sun, and X. D. Feng, Microspheres of Biodegradable Block Copolymer for Long-Acting Controlled Delivery of Contraceptives, Polymer Journal, vol.3, issue.5, pp.485-491, 1987.
DOI : 10.1021/ma00142a057

P. Carino, J. S. Jacob, and E. Mathiowitz, Nanosphere based oral insulin delivery, Journal of Controlled Release, vol.65, issue.1-2, pp.261-269, 2000.
DOI : 10.1016/S0168-3659(99)00247-3

R. Constancis, N. Meyrueix, S. Bryson, J. M. Huille, T. Grosselin et al., Macromolecular Colloids of Diblock Poly(amino acids) That Bind Insulin, Journal of Colloid and Interface Science, vol.217, issue.2, pp.357-368, 1999.
DOI : 10.1006/jcis.1999.6383

H. Gotsche, H. Keul, and . Höcker, Amino-termined poly(L-lactide)s as initiators for the polymerization of N-carboxyanhydrides: synthesis of poly(L-lactide)-block-poly(??-amino acid)s, Macromolecular Chemistry and Physics, vol.196, issue.12, pp.3891-3903, 1995.
DOI : 10.1002/macp.1995.021961203

H. Tasaka, Y. Miyazaki, T. Oya, and . Ouchi, Synthesis of Comb-Type Biodegradable Polylactide through Depsipeptide???Lactide Copolymer Containing Serine Residues, Macromolecules, vol.32, issue.19, pp.6386-6389, 1999.
DOI : 10.1021/ma990766n

K. E. Jin and . Gonsalves, Synthesis of poly(l-lactide-co-serine) and its graft copolymers with poly(ethylene glycol), Polymer, vol.39, issue.21, pp.5155-5162, 1998.
DOI : 10.1016/S0032-3861(97)10374-3

A. Barrera, E. Zylstra, P. T. Lansbury, and R. Langer, Synthesis and RGD peptide modification of a new biodegradable copolymer: poly(lactic acid-co-lysine), Journal of the American Chemical Society, vol.115, issue.23, pp.11010-11011, 1993.
DOI : 10.1021/ja00076a077

A. Barrera, E. Zylstra, P. T. Lansbury, and R. Langer, Copolymerization and Degradation of Poly(lactic acid-co-lysine), Macromolecules, vol.28, issue.2, pp.425-432, 1995.
DOI : 10.1021/ma00106a004

S. Hrkach, J. Ou, N. Lotan, and R. Langer, Synthesis of Poly(L-lactic acid-co-L-lysine) Graft Copolymers, Macromolecules, vol.28, issue.13, pp.4736-4739, 1995.
DOI : 10.1021/ma00117a055

K. Elisseeff, R. Anseth, J. S. Langer, and . Hrkach, -aspartic acid), Macromolecules, vol.30, issue.7, pp.2182-2184, 1997.
DOI : 10.1021/ma961411w

URL : https://hal.archives-ouvertes.fr/hal-00555504

J. S. Caponetti, B. Hrkach, M. Krivet, N. Pohl, P. Lotan et al., Microparticles of Novel Branched Copolymers of Lactic Acid and Amino Acids: Preparation and Characterization, Journal of Pharmaceutical Sciences, vol.88, issue.1, pp.136-141, 1999.
DOI : 10.1021/js970457f

S. Vert, H. Li, and . Garreau, More about the degradation of LA/GA-derived matrices in aqueous media, Journal of Controlled Release, vol.16, issue.1-2, pp.15-26, 1991.
DOI : 10.1016/0168-3659(91)90027-B

URL : https://hal.archives-ouvertes.fr/hal-00417736

K. Ajioka, K. Enomoto, A. Suzuki, and . Yamaguchi, The basic properties of poly(lactic acid) produced by the direct condensation polymerization of lactic acid, Journal of Environmental Polymer Degradation, vol.40, issue.3, p.225, 1995.
DOI : 10.1007/BF02068677

H. Cherdron, F. Ohse, and . Korte, Die polymerisation von lactonen. Teil 1: Homopolymerisation 4-, 6- und 7-gliedriger lactone mit kationischen initiatoren, Die Makromolekulare Chemie, vol.56, issue.1, p.179, 1962.
DOI : 10.1002/macp.1962.020560113

Y. Ito, Y. Hashizuka, and . Yamashita, Equilibrium Cyclic Oligomer Formation in the Anionic Polymerization of i??-Caprolactone, Macromolecules, vol.10, issue.4, p.821, 1977.
DOI : 10.1021/ma60058a019

. Yamashita, Anionic Polymerization : Kinetics, Mecanism and Synthesis, Mc Grath Ed, ACS Symposium Series, pp.166-199, 1981.

D. Lundberg and F. F. Cox, Ring Opening Polymerization, Makromol. Chem, vol.56, issue.11, p.179, 1962.

R. Kricheldorf, M. Berl, and N. Scharnagl, Poly(lactones). 9. Polymerization mechanism of metal alkoxide initiated polymerizations of lactide and various lactones, Macromolecules, vol.21, issue.2, p.286, 1988.
DOI : 10.1021/ma00180a002

R. Kricheldorf, M. Berl, and N. Scharnagl, Poly(lactones). 9. Polymerization mechanism of metal alkoxide initiated polymerizations of lactide and various lactones, Macromolecules, vol.21, issue.2, p.286, 1988.
DOI : 10.1021/ma00180a002

P. Ropson, R. Dubois, and . Jerome, Macromolecular engineering of polylactones and polylactides. 14. A carbon-13 and aluminum-27 NMR study of the effect of .gamma.-butyrolactone on the structure of aluminum isopropoxide in toluene, Macromolecules, vol.26, issue.24, p.6378, 1993.
DOI : 10.1021/ma00076a012

R. Heushen, . Jerome, . Ph, and . Teyssié, Polycaprolactone-based block copolymers. 1. Synthesis by anionic coordination type catalysts, Macromolecules, vol.14, issue.2, p.242, 1981.
DOI : 10.1021/ma50003a003

B. Bassi, A. B. Padias, and H. K. Hall, The hydrolytic polymerization of ??-caprolactone by triphenyltin acetate, Polymer Bulletin, vol.25, issue.2, p.227, 1990.
DOI : 10.1007/BF00297322

J. Nijenhuis and D. W. Gripjma, Lewis acid catalyzed polymerization of L-lactide. Kinetics and mechanism of the bulk polymerization, Macromolecules, vol.25, issue.24, p.6419, 1992.
DOI : 10.1021/ma00050a006

J. Du, P. J. Lenstra, A. J. Nijenhuis, H. A. Van-aert, and C. Bastiaansen, ABA Type Copolymers of Lactide with Poly(ethylene glycol). Kinetic, Mechanistic, and Model Studies, Macromolecules, vol.28, issue.7, p.2124, 1995.
DOI : 10.1021/ma00111a004

R. Kricheldorf, I. Kreiser-saunders, and C. Boettcher, Polylactones: 31. Sn(II)octoate-initiated polymerization of L-lactide: a mechanistic study, Polymer, vol.36, issue.6, pp.1253-1259, 1995.
DOI : 10.1016/0032-3861(95)93928-F

R. C. Dittrich and . Schultz, Kinetik und Mechanismus der ring??ffnenden Polymerisation von L(???)-Lactid, Angewandte Makromolekulare Chemie, vol.15, issue.1, p.109, 1971.
DOI : 10.1002/apmc.1971.050150109

D. Ethel-browning, J. Schwach, R. Coudane, M. Engel, and . Vert, Toxicity of Industrial Metal, Polym. Bull, vol.44, issue.29, pp.313-76, 1961.

J. Schwach, R. Coudane, M. Engel, and . Vert, Ring opening polymerization ofD,L-lactide in the presence of zinc metal and zinc lactate, Polymer International, vol.46, issue.3, pp.177-182, 1998.
DOI : 10.1002/(SICI)1097-0126(199807)46:3<177::AID-PI937>3.0.CO;2-S

J. Kleine and H. Kleine, ??Ber hochmolekulare, insbesondere optisch aktive polyester der milchs??ure, ein beitrag zur stereochemie makromolekularer verbindungen, Die Makromolekulare Chemie, vol.30, issue.1, p.23, 1959.
DOI : 10.1002/macp.1959.020300102

A. Nijenhuis, D. W. Grijpma, and A. J. Pennings, Lewis acid catalyzed polymerization of L-lactide. Kinetics and mechanism of the bulk polymerization, Macromolecules, vol.25, issue.24, p.6419, 1992.
DOI : 10.1021/ma00050a006

R. Kricheldorf and D. Damrau, Polylactones, 37. Polymerizations of L-lactide initiated with Zn(II) L-lactate and other resorbable Zn salts, Macromolecular Chemistry and Physics, vol.198, issue.6, pp.1753-1766, 1997.
DOI : 10.1002/macp.1997.021980605

M. Stevels, M. J. Ankoné, P. J. Dijkstra, and J. Feijen, Well defined block copolymers of ??-caprolactone and L-lactide using Y5(??-O)(OiPr)13 as an initiator, Macromolecular Chemistry and Physics, vol.196, issue.4, p.1153, 1995.
DOI : 10.1002/macp.1995.021960415

M. Stevels, M. J. Ankoné, P. J. Dijkstra, and J. Feijen, -butylphenolate)s and Various Alcohols, Macromolecules, vol.29, issue.9, p.3332, 1996.
DOI : 10.1021/ma951813o

URL : https://hal.archives-ouvertes.fr/jpa-00225251

. Save, Polymérisation d'esters cycliques amorcée par un dérivé de terre rare, p.2285, 2000.

W. H. Carothers, Polymerization., Chemical Reviews, vol.8, issue.3, p.353, 1931.
DOI : 10.1021/cr60031a001

H. Leuchs, Ueber die Glycin-carbons??ure, Berichte der deutschen chemischen Gesellschaft, vol.36, issue.1, p.857, 1906.
DOI : 10.1002/cber.190603901133

F. Wessely and . Sigmund, Untersuchungen ??ber ??-Amino-N-Carbons??ureanhydride. I., Hoppe-Seyler??s Zeitschrift f??r physiologische Chemie, vol.146, issue.1-3, p.72, 1925.
DOI : 10.1515/bchm2.1925.146.1-3.72

F. Wessely and . Sigmund, Untersuchungen ??ber ??-Amino-N-Caxbons??ureanhydride. III. (Zur Kenntnis h??hermolekalarer Verbindungen.), Hoppe-Seyler??s Zeitschrift f??r physiologische Chemie, vol.159, issue.1-4, p.102, 1926.
DOI : 10.1515/bchm2.1926.159.1-4.102

F. Wessely and M. John, ???ber Carbonyl-bis-aminos???uren und deren Umwandlungsprodukte II, Monatshefte f???r Chemie, vol.50, issue.1, p.439, 1928.
DOI : 10.1007/BF01552465

M. Idelson and E. R. Blout, A Kinetic Study of the Polymerization of Amino Acid N-Carboxyanhydrides Initiated by Strong Bases, Journal of the American Chemical Society, vol.80, issue.10, p.2387, 1958.
DOI : 10.1021/ja01543a012

M. Sela and A. Berger, The Terminal Groups of Poly-??-amino Acids, Journal of the American Chemical Society, vol.77, issue.7, p.1893, 1955.
DOI : 10.1021/ja01612a054

A. Terbojevitch, E. Cosani, E. Peggion, and . Scoffone, Effects of temperature on the polymerization of ?-ethylDL-glutamateN-carboxy anhydride in DMF initiated by tri-n-propylamine, Biopolymers, vol.182, issue.1, p.129, 1971.
DOI : 10.1002/bip.360100110

D. Lundberg, P. E. Doty, W. G. Nylund, and . Miller, Polypeptides. XVII. A Study of the Kinetics of the Primary Amine-initiated Polymerization of N-Carboxy-anhydrides with Special Reference to Configurational and Stereochemical Effects, Journal of the American Chemical Society, vol.79, issue.15, pp.3961-112, 1957.
DOI : 10.1021/ja01572a004

D. Williams, M. Eshaque, and R. D. Brown, Stereoselective polymerization of ??-Benzyl Glutamate NCA, Biopolymers, vol.83, issue.4, p.753, 1971.
DOI : 10.1002/bip.360100412

P. Doty and R. D. Lundberg, POLYPEPTIDES. X. CONFIGURATIONAL AND STEREOCHEMICAL EFFECTS IN THE AMINE-INITIATED POLYMERIZATION OF N-CARBOXYANHYDRIDES, Journal of the American Chemical Society, vol.78, issue.18, p.4810, 1956.
DOI : 10.1021/ja01599a072

D. Williams, M. Eshaque, and R. D. Brown, Stereoselective polymerization of ??-Benzyl Glutamate NCA, Biopolymers, vol.83, issue.4, p.753, 1971.
DOI : 10.1002/bip.360100412

M. Idelson and E. R. Blout, Infrared Spectroscopy and the Kinetics of the Synthesis of Polypeptides: Primary Amine Initiated Reactions, Journal of the American Chemical Society, vol.79, issue.15, p.3948, 1957.
DOI : 10.1021/ja01572a002

N. Sato, Synthesis and properties of new luminescent 10-carboxymethylacridinium derivatives, Tetrahedron Letters, vol.37, issue.47, p.8519, 1996.
DOI : 10.1016/0040-4039(96)01980-6

S. Bechaouch, B. Coutin, and H. Sekiguchi, Improvement of the synthesis of poly(L-cystyl-L-cystine): a new biodegradable polymer, Macromolecular Chemistry and Physics, vol.197, issue.5, p.1661, 1996.
DOI : 10.1002/macp.1996.021970508

B. Gachard, H. Coutin, and . Sekiguchi, Synthesis and characterization of polyamides based on natural monomers: l-lysine and l-aspartic acid, Polymer Bulletin, vol.192, issue.6, pp.643-649, 1997.
DOI : 10.1007/s002890050100

. La-quatrième-Étape, Elle se produit après hydrolyse poussée, quand la taille des fragments leur permet d'être assimilés par phagocytose ou quand on obtient des monomères ioniques solubles (lactate) dans le fluide inter-cellulaire. C'est à ce niveau qu

. Durant-cette-phase, la majeure partie des produits de dégradation du PLA est éliminée par la respiration (CO 2 ) et seulement une faible partie de ces produits est éliminée par l'excrétion (urine/fécès)

H. Benninga and W. H. Carothers, A History of Lactic Acid Making, J. Am. Chem. Soc, vol.54, p.761, 1932.

D. Bendix, Chemical synthesis of polylactide and its copolymers for medical applications, Polymer Degradation and Stability, vol.59, issue.1-3, pp.129-135, 1998.
DOI : 10.1016/S0141-3910(97)00149-3

S. Li and M. Vert, Biodegradation of Aliphatic Polyesters, Degradable Polymers, 1995.

R. Ottenbrite, Discussion on Degradation Terminology, Biodegradable Polymers & Plastics, Royal Society of Chemistry, pp.73-92, 1992.

S. Gogolewski and J. Pennings, Resorbable materials of poly(L-lactide). II. Fibers spun from solutions of poly(L-lactide) in good solvents, Journal of Applied Polymer Science, vol.28, issue.3, pp.1045-1061, 1983.
DOI : 10.1002/app.1983.070280312

R. R. Bos, F. R. Rozema, G. Boering, A. J. Nijenhuis, A. J. Pennings et al., Degradation of and tissue reaction to biodegradable poly(L-lactide) for use as internal fixation of fractures: a study in rats, Biomaterials, vol.12, issue.1, p.32, 1991.
DOI : 10.1016/0142-9612(91)90128-W

H. Lewis, Biodegradable Polymers as Drug Delivery Systems, 1990.

Y. Matsusue, T. Yamamuro, S. Yoshiri, M. Oka, Y. Ikada et al., Biodegradable screw fixation of rabbit tibia proximal osteotomies, Journal of Applied Biomaterials, vol.96, issue.1, pp.1-12, 1991.
DOI : 10.1002/jab.770020102

J. E. Bergsma, F. R. Rozema, R. R. Bos, G. Boering, W. C. De-brijn et al., In vivo degradation and biocompatibility study of in vitro pre-degraded as-polymerized polylactide particles, Biomaterials, vol.16, issue.4, pp.267-274, 1995.
DOI : 10.1016/0142-9612(95)93253-A