报告题目：Smart polymer nanostructures for therapy and diagnosis
报告人: Min-Hui LI
Curie Physical Chemistry Laboratory, Institut Curie,
26 rue d’Ulm, 75248 Paris 05, France
Synthetic amphiphilic polymers have been largely developed since last decades for the purpose of forming self-assembled polymer vesicles (polymersomes) which mimick lipid vesicles (liposomes). Polymersomes are much more stable, more robust and less permeable than liposomes due to the high molecular weight of polymers. Another interesting feature of polymersomes is that their properties can be tuned extensively by chemical design of the amphiphilic building blocks. These nanostructures are currently studied as a means of drug delivery and biomedical imaging for their ability to entrap hydrophobic molecules in the membrane and encapsulate hydrophilic ones in the inner aqueous compartment. The tailor design of smart polymersomes, i.e., stimuli-responsive polymersomes bearing a protective coat, site-specific targeting ligands and a cell-penetrating function, is state-of-the-art research in this field. The research of our group has focused, since several years, on the development of stealth and stimuli-responsive polymersomes made from amphiphilic block copolymers. We develop robust and responsive nanostructures by combining the properties of two kinds of soft materials, polymers and liquid crystals (LC). Unique polymer nanoaggregates self-assembled by amphiphilic block copolymers, which are composed of a hydrophilic PEG block and a hydrophobic liquid crystal polymer block, will be described in this talk. The responsiveness of the nano-aggregates (disassembling or morphological control) is triggered by physical stimuli via either polymer conformational change or liquid crystal phase change.
My talk consists of two parts. In the first part I will describe photo-responsive and thermal responsive polymer vesicles (polymersomes). Three systems of photo-responsive polymersomes have been developed using different molecular design. Their bursting and wrinkling can be induced by UV light illumination. For example, using a linear-linear block copolymer, a nano-actuator design, i.e. a 10 nm-thick bimorph with only one UV responsive layer made of nematic side-chain LC polymers, is used to constitute the bilayer membrane of a spherical polymersomes. The photo-actuation of the membrane creates a spontaneous curvature in the membrane and results in instantaneous polymersome bursting. The versatility of this actuator mechanism should broaden the range of applications of polymersomes in fields such as drug delivery, cosmetics and material chemistry. We have also investigated in detail the thermal-responsive properties of LC polymersomes. The structural changes of polymersomes studied by small angle neutron scattering and cryo-electron microscopy will be discussed.
In the second part, I will describe the unique self assembly structures of amphiphilic LC block copolymers. Thermotropic LC phases exhibit in the lyotropic nano-structures. The additional internal LC order in the bilayer membrane can lead to significantly deformed vesicles as a result of the delicate interplay between two- dimensional ordering and vesicle shape. The inevitable topological defects in structured vesicles of spherical topology also play an essential role in controlling the final vesicle morphology. Nano-size cylindrical micelles (nano-fibers), faceted tetrahedral vesicles, and ellipsoidal vesicles, as well as cylindrical vesicles, were observed. The tetrahedral vesicle is a particularly fascinating example of a faceted liquid-crystalline membrane, which may lead to the design of supra-molecular structures with tetrahedral symmetry and new classes of nano-carriers.
1981～1986年 北京清华大学化工系高分子材料专业 学士
1986～1989年 北京清华大学化工系高分子材料专业 硕士
1993～1994年 法国石油研究院 博士后
1994～1997年 法国国家科研中心研究员，任职于化学部波尔多地区Paul Pascal 研究中心， 从事液晶化学研究
2008～2010年 复旦大学高级访问学者（短期）, 合作者：江明院士
科学期刊发表文章数目: 53； H-factor = 21，引用次数：1050
Proc. Natl. Acad. Sci. U. S. A.: 1 ; J. Am. Chem. Soc.: 2
Phys. Rev. Lett. : 2; Adv. Mater.: 2
Chem. Commun.: 2; Soft Matter: 7
Macromolecules: 8; Phy. Rev. E: 3