Elastin-like block copolymer

The immunogenicity of SLP-F and SELF copolymers has been evaluated in rabbits. Compared to hyperimmune positive control rabbit sera, the immunogenicity of all pol5rmers was found to be relatively low. In cases where an elevated antibody titer was observed (e.g., against SLP-F), the antibody response was found to be directed only at the silk-like blocks of the polymer. No response was detected against the elastin-like blocks or fibronectin cellular attachment sites (2). 

Elastin-like polypeptide block copolymer ELP(ViAaG7-n] I ELPBfs-nl... 

Conticello and colleagues have studied the potential of amphiphilic diblock (AB) and triblock (ABA) elastin-like copolymers, where A is a hydrophilic and B a hydrophobic block, to reversibly self-assemble into well-defined micellar aggregates (20,30). Collapse of the hydrophobic block above Tt results in the formation of elastin-based nanoparticles. To provide diversity in the mechanical properties of the micellar structures, the amino acid sequence of the hydrophobic block was varied between plastic (VPAVG) and elastomeric (VPGVG) in nature. The hydrophilic block is designed to maintain solubility and form a protective core that prevents protein adsorption and clearance by the reticuloendothelial system. 

The principal mechanism of temperature-sensitive polymers is the sharp transition from coil to globule in water on heating, indicating a change from a hydrophilic state (coil) below the lower critical solution temperature (LCST) to a hydrophobic state (globule) above the LCST. Representative temperature-sensitive polymers include A -isopropylacrylamide (NIPAAm), its copolymers (LCST 30-50°C) [108, 124-127], polyester block copolymers (20-100°Q [97, 128], and elastin-like polypeptides (27-40°C) [129-131]. To achieve both spatial and temporal control in conjunction with local temperature increases (2-5°C), the LCST of a given polymer can be tailored through its comonomer composition, hydrophilic-hydrophobic balance, stereochemistry [125-127,132], and the addition of salts and surfactants [133]. These thermosensitive polymers with controlled LCSTs (around body temperature) can be applied to specific applications (e.g., tumor treatment). 

Nagarsekar, A., Crissman, J., Crissman, M. et al. (2002) Genetic synthesis and characterization of pH-and temperature-sensitive silk-elastin-like protein block copolymers. Journal of Biomedical Materials Research, 62,195-203. 

Jia and coworkers took advantage of CuAAC to design an elastin-like peptide-polymer conjugate. The reaction between a bifunctional, azide-terminated PEO block and an alkyne-functionalized peptide composed of two different functional domains yielded a multiblock copolymer (Figure 1.12). 

Lim DW, Nettles DL, Setton LA, Chilkoti A (2008). In situ cross-linking of elastin-like polypeptide block copolymers for tissue repair. Biomacromoiecuies, 9,222-230. 

---