BULK AND SOLUTION PROPERTIES OF PEPTIDE-POLYMER CONJUGATES - Biologically-Responsive Hybrid Biomaterials - page 37

related to the release rate of encapsulated drugs. Another interesting strategy was
reported by Kataoka et al. [112] regarding the first semi-permeable vesicles,
called PICsomes, that were formed using a charge-driven approach with a PEG-
P(Asp)/PEGP(Asp-AP) system in water. In addition, a recent development in this
research area consists of employing building blocks with a specific functionality.
Deming et al. [121] reported highly relevant work on the formation of poly( L -
leucine)- b -poly(arginine) block copolymers. In this system, the poly(arginine)
segment was used both to direct structure for vesicle formation and to provide
biofunctionality for efficient intracellular delivery of the vesicles, mimicking the
arginine-rich sequences identified as significant in protein-transduction domains.
Though outside the peptide-polymer focus of this chapter, the field of
protein-like polymers merits mention as a promising area for future research.
Recombinant DNA techniques allow fine-tuning of amino acids within the
polymer chain, thereby determining specific biological functions (including
properties such as degradation), in addition to imparting intrinsic
biocompatibility. The most studied polypeptide sequences thus far exhibit
elastin-like structures. For example, Dreher et al . [129] and Chaikof et al . [130]
reported on the temperature-triggered formation of spherical micelles with
elastin-like polypeptide (ELP) motifs.
We have no doubt that the published literature in this domain, which has
matured dramatically in the last 2-3 years, will continue to exhibit tremendous
growth in the next few years. A range of scientific communities, from materials
sciences to colloidal sciences, stand to benefit in the near future. The potential
impact is profound for biological applications, particularly in the area of drug
delivery, but also in biomaterials and tissue engineering.
Materials
AP, 5-aminopentyl; BF, bovine fibrinogen; BSA, bovine serum albumine; DGBE,
poly(diethylene glycol bis(3-amino propyl) ether); DMF, dimethylformamide;
DTT, dithiothreitol; ELP, elastin-like polypeptide; PAA, poly(acrylic acid);
PAELA, poly(2-acryloyloxyethyllactoside); PAI, poly(acetyliminoethylene); PAP,
poly(5-aminopentyl); PAsp, poly( Ȳ , ŋ -aspartic acid); PB, polybutadiene; PBA,
poly(butylacrylate); PBAN, poly(butadiene- co -acrylonitrile; PBGlu (poly(γ-benzyl
D , L -glutamate); PBLAsp, poly(β-benzyl L -aspartate); PBS, phosphate buffer
solution; PBLG, poly( ȳ -benzyl L -glutamate); PCL, poly(ε-caprolactone); PDMS,
polydimethylsiloxane; PECF, pseudoextracellular fluid; PEG, poly(ethylene
glycol); PELGlu, poly(γ-ethyl L -glutamate); PELLys, ethylene glycol-modified
poly( L -lysine); PEO, poly(ethylene oxide); PEUU, polyetherurethaneurea; PFS,