Self-assembling polymeric structures are highly important in the field of biomaterials, especially when explicit biological responses are expected of these self-assembled (delivery) systems. Amphiphilic block copolymers consisting of poly(ethylene glycol), PEG, and poly(amino acid), PAA, segments are uniquely suited to construct biomedically relevant delivery systems because PEG conveys biocompatibility and PAAs, which can be formed from (any of the natural occurring) amino acid, convey the physical properties and chemical functionalities of the respective amino acid building blocks. PEGylated PAAs are synthesized using an amino-terminated PEG as macroinitiator for the ring opening polymerization of the amino acid N-carboxyanhydrides. Depending on the molecular architecture the amphiphilicity of PEGylated PAAs can be controlled; benzyl-L-glutamate, the protected form of glutamate is highly hydrophobic, after a deprotection an L-glutamate salt is formed that enhances the water solubility of the block copolymer. Here, details of the self-assembly of block copolymers consisting of PEG and blocks of p(L-Glutamate) or p(L-Lysine) and p(L-Leucine) will be discussed. The TEM image shown below of a triblock copolymer consisting of PEG, p(Benzyl-L-Glu) (phenyl rings of p(Benzyl-L-Glu) are stained with Ruthenium tetraoxide) and p(L-Leu) indicates a unique self-assembly: Small polymeric particles assemble into larger, irregular aggregates. These TEM images corroborate the bimodal particle size distribution observed by DLS when these block copolymers are exposed to the selective solvent water. PEGylated PAA block copolymers containing p(L-Lysine) and p(L-Leucine) were investigated for their ability to condense DNA, which is enabled by the cationic charge provided by p(L-Lys) blocks, results will be discussed.

Self-assembly of PEGylated poly(amino acid)s and their use in DNA complexation

249th National Meeting (2015)

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