Auto-assemblage de copolymères à blocs amphiphiles Suming LI Institut Européen des Membranes Université de Montpellier 34095 Montpellier, France
Self-assembly of amphiphilic block copolymers Colloidal systems : - hydrogels, - micelles, - polymersomes... Applications in drug delivery
PLA/PEG block copolymers Poly(lactic acid) : PLA Poly(ethylene glycol) : PEG -(--CH-C-) * n - CH 3 -(-CH 2 -CH 2 --) n - - biocompatible - biobased - degradable - Hydrophobic - L- and D-enantiomers - biocompatible - bioresorbable (Mn < 30000) - water soluble
Synthesis of ABA and AB-type PLA/PEG copolymers Ring opening polymerization (RP) of lactide with PEG: CH 3 H CH 3 H + H(-CH 2 -CH 2 --) n H H H H-(-C-C-) x -(-CH2 -CH2-) n-(-c-c-) x H CH 3 CH 3 L-Lactide D-lactide DL-lactide PEG Mn=2K - 20K PLLA-PEG-PLLA (L x E y L x ) PDLA-PEG-PDLA (D x E y D x ) PDLLA-PEG-PDLLA (DL x E y DL x ) CH 3 H L-Lactide D-lactide CH 3 H H + H(-CH 2 -CH 2 --) n CH 3 H-(-C-C-) x -(-CH 2 -CH 2 -) n -CH 3 CH 3 mpeg Mn=2K, 5K PLLA-PEG (L x E y ) PDLA-PEG (D x E y )
Synthesis of BAB-type PEG-PLA-PEG copolymers by combination of RP and click chemistry n H x Zn(Lac) 2 n H 2x mpeg-plla mpeg L-Lactide H DCC, DMAP mpeg H m 1. MSCl, Et 3 N 2. NaN 3 N 3 m n CuBr, PMDETA 2x n 2x N N N m PEG-PLLA-PEG (E x L y E z )
Hydrogels
Formation of hydrogels from PLA/PEG aqueous solutions due to stereocomplexation between L-PLA and D-PLA blocks 20% L 12 E 104 L 12 solution after 48h at 25ºC Hydrogel formed by 20% L 12 E 104 L 12 / D 13 E 104 D 13 solution after 48h at 25ºC
Stereocomplex of poly(l-lactide) and poly(d-lactide) Both PLLA and PDLA are crystalline polymers with a pseudoorthorhombic crystal of 10 3 helix, ptically active PLLA and PDLA can form a stereocomplex by blending in solution or in melt, with triclinic crystal of 3 1 helix. PLLA Stereocomplex 2 4 6 8 10 12 14 16 18 20 Theta (degree) X-ray diffraction spectra of PLLA and PLLA/PDLA stereocomplex
Time-dependent gelation of aqueous solutions of L-PLA/PEG and D-PLA/PEG 250 G' Modulus (Pa) 200 150 100 G" 50 0 0 1 2 3 4 5 6 7 Time (hours) Time-dependent changes of storage (G') and loss moduli (G") of a 15% L 12 E 104 L 12 / D 13 E 104 D 13 sample at 37ºC and at 1Hz
Release profiles of bovine serum albumin (BSA) 50 15% BSA Released (%) 40 30 20 10 20% 25% 30% 0 0 50 100 150 200 250 Time (h) BSA release from L 28 E 113 / D 27 E 113 hydrogels with different concentrations
Spherical Micelles
Self-assembly micelles prepared by direct dissolution of PLA/PEG in water PLA-PEG diblock PLA-PEG-PLA triblock PEG blocks PLA blocks
Size distribution of single and mixed micelles by DLS 100 Lc 21 E 454 L 21 100 L 21 E 454 L 21 /D 22 E 454 D 22 80 80 60 210 nm 60 154 nm 40 40 20 20 0 0 10 100 1000 Diameter (nm) 10 100 1000 Diameter (nm)
TEM micrographs of L/D mixed micelles L 21 E 454 L 21 + D 22 E 454 D 22
Critical micelle concentration determination of PLA/PEG copolymers from surface tension measurements 58 56 (mn/m) 54 52 50 CMC 48 L 12 E 45-2.0-1.8-1.6-1.4-1.2-1.0 lgc (g/l)
Determination of the aggregation number (Nagg) of micelles by aqueous GPC L 25 E 114 N agg = M W micelle M W unimer 0.25g/l Mw=7650 Mw=292000 10g/l 5 10 15 20 25 Time (min)
Efficient anticancer drug (ovarian cancer, breast cancer, lung cancer ) Poor aqueous solubility (< 0.5 g/ml ) Paclitaxel Taxol : 50:50 (v/v) Cremophor EL and dehydrated alcohol (hypersensitivity, neurotoxicity ) PLA/PEG micelles (great potential as paclitaxel carrier)
PTX Paclitaxel release from PLA/PEG micelles in PBS at 37 o C 70 60 L 12 E 104 L 12 Released TAX (%) 50 40 30 20 10 L 12 E 104 L 12 /D 13 E 104 D 13 0 0 5 10 15 20 25 30 Release time (d)
Antitumor efficacy of PTX-loaded micelles as compared to saline and clinical formulation on female mice bearing lung cancer cells 7 Mean relative tumor volume 6 5 4 3 2 1 Saline 1-mixed L 12 E 104 Lmicelles 12 /D 13 E 104 D 13 -PTX Clinical Formulation 0 0 1 2 3 4 5 6 7 8 Days after administration
Rod-like Micelles
TEM micrographs of rod-like micelles obtained from PLA/PEG copolymers with high PEG fraction D 11 E 91 D 11 D 31 E 114
Schematic presentation of micelles prepared from high PEG fraction PLA/PEG copolymers (A) micelle with void, (B) rod-like micelle (A) (B)
Worm-like Micelles (filomicelles)
Morphological changes as a function of E/LA ratio for PEG5000 derived diblock copolymers L 54 E 114 L 63 E 114 500 nm L 85 E 114 L 63 E 114 500 nm
Morphological changes as a function of E/LA ratio for PEG2000 derived diblock copolymers L 18 E 45 L 22 E 45 1 μm L 41 E 45 L 73 E 45 1μm 1μm 200 nm
Polymersomes
TEM images of polymersomes obtained from BABtype E 45 L 46 E 113 copolymers a b 200 nm 200 nm c d 100 nm 100 nm
Nanotubes
TEM images of nanotubes obtained from BAB-type E 12 LA 21 E 45 copolymers a b 200 nm 200 nm c d 200 nm 200 nm
TEM images of nanotubes obtained from BAB-type E 12 LA 46 E 113 copolymers a b 200 nm 200 nm c d 200 nm 200 nm
AFM images of polymersomes and nanotubes
Schematic presentation of polymersomes and nanotubes prepared from PEG-PLA-PEG copolymers N agg f N agg > f Geometry: Thermodynamics: N agg ~ length of the chains
Reverse micelles
Normal micelles and reverse micelles PLA block PEG block Normal micelle in H 2 Reverse micelle in organic solvents
Reverse micelles formation Dissolution of PLA/PEG in toluene-ethanol Addition of water Stirring transparent/translucent (a) (b) (c) (a) D 24 E 182 D 24 (b) D 21 E 91 D 21 (c) E 45 L 6 (a) (b) (c)
DLS and TEM of reverse micelles prepared from D21E91D21
DLS results of blank reverse micelles Copolymer Water (m<<l) Mean size (nm) E 45 L 12 0.06 30.6 E 45 L 6 0.06 18.0 E 113 D 31 0.06 32.9 E 113 L 46 0.1 44.4 L 12 E 91 L 12 0.06 64.9 D 11 E 91 D 11 0.06 60.9 D 21 E 91 D 21 0.08 50.9 L 25 E 182 L 25 0.08 66.6 D 24 E 182 D 24 0.08 63.2
Conclusion Various colloidals such as hydrogels, spherical and anisotropic micelles, filomicelles, polymersomes and reverse micelles can be obtained by self-assembly of PLA/PEG copolymers, These systems present great potential as injectable drug delivery carriers, in particular proteins, peptides, and hydrophobic anticancer drugs.
ACKNWLEDGEMENTS Thi Bich Tran Nguyen, André Deratani Institut Européen des Membranes, Université de Montpellier, France Xiaohan Wu, Vincent Darcos, Abdelslam El Ghzaoui Institut des Biomolécules Max Mousseron, Université de Montpellier, France Liu Yang, Zhongyong Fan Department of Materials Science, Fudan University, Shanghai, China Yourong Duan, Fei Mo Shanghai Cancer Institute, Xietu Road, Shanghai 200032, China Katarzyna Jelonek, Janusz Kasperczyk Canter of Carbon and Polymer Materials, Polish Academy of Sciences, Zabrze, Poland Financial supports : - Ministry of Education of France, - PICS CNRS of France - Chinese Scholarship Council
Merci