Frantisek Rypácek,1 Stepan Popelka,1,2 Lucie Bacáková, 3 Ludka Machová,1
Vladimir Proks,1,2 Dana Kubies,1,2 and R. Kotva1
1 Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq.2,
162 06 Prague, Czech Republic; 2 Center for Cell Therapy and Tissue Repair, 2nd Faculty of Medicine,
Charles University, Prague, Czech Republic; 3 Institute of Physiology, Academy of Sciences of the Czech
Republic, Videnska 1084, Prague, Czech Republic. Phone: +420-296 809 241; Fax: +420-296 809
410; E-mail: rypacek@imc.cas.cz

　Recent progresses in stem cells technologies and growing promises of their use in cell therapy and tissue engineering, call for new biomimetic polymer materials that could be used as scaffolds for implanted cells. In addition to tuned mechanical properties and suitably designed three-dimensional architecture of the scaffolds, the interaction between the biomaterial and living cells becomes of key importance. Adhesion, proliferation and differentiation of cells on polymer substrates can be modified by providing solid-state signals to the cells through specific structures exposed on the polymer surfaces.
　The presented work uses amphiphilic block copolymers, composed of hydrophobic polyester and hydrophilic poly(ethylene oxide) (PEO) or poly(α-amino acid) (PAA) blocks, to modify surface properties of polyester-based biomaterials. The surface deposition of polyester-derived block copolymers preserves the bulk physical properties of the material while allowing us to introduce not only various nonspecific functional groups, but also specific peptide sequences derived from extracellular-matrix proteins, e.g., peptide fragments of fibronectin and laminin.
　Alternative strategies for the synthesis of copolymers capped with peptide sequences are presented. PAA-b-PLA block copolymers were prepared by successive living polymerizations of amino acid   N-carboxyanhydrides and lactide. The RGD peptide sequence can be incorporated at the end of hydrophilic PAA block by combining the initiation and capping steps in the synthesis of PAA [1].
　End-functional PLA-b-PEO copolymers were obtained by polymerization of lactide using semitelechelic PEO with protected carboxyl or amino groups as co-initiators of controlled lactide polymerization. Solid-phase techniques based on building a protected peptide on a polymer support and using functional copolymers as final reactants, were applied to the synthesis of well-defined copolymers capped with selected peptide sequences [2].
　Functional polymer surfaces and composite polymer brushes with controlled distribution of adhesion structures have been prepared through surface deposition of functional block copolymers using various strategies [3,4]. Vascular smooth-muscle and endothelial cells were used in cell cultivation studies to evaluate the effect of surface modifications on cell adhesion and growth on polymer films [5]. Thus, functional amphiphilic block copolymers can be used as a versatile modular system providing for different types of bioactive, patterned surfaces of polymer biomaterials, exhibiting selective interactions at biomaterial-cell interfaces.

Acknowledgment: Support from the Grant Agency of the Academy of Sciences CR (grant No. A4050202), Grant Agency of CR (grant No. 304/02/0579) and the Ministry of Education of CR (grant No. LN00A065) is acknowledged.

References
[1] Rypacek, F., Machova, L., Kotva, R., Skarda, V., Polym. Mater. Sci. Eng. 84, 817, 2001.
[2] Proks, V., Machova, L., Popelka, S., Rypacek, F. Adv. Exp.Med. Biol., 534, 191, 2003.
[3] Kubies, D., Rypácek, F., Kovarova, J., and Lednicky, F., Biomaterials 21, 529, 2000.
[4] Kubies, D., Machova, L., Brynda, E., and Rypacek, F., J. Mater. Sci, Mater. Med., 14, 143, 2003.
[5] Bacakova L., Lapcikova M., Kubies D., and Rypacek F., Adv. Exp. Med. Biol., 534, 179, 2003.

　论文来源：International Symposium on Polymer Chemistry,June,2004