Hydrophobically driven self-assembly is a well-understood principle that has been shown to facilitate micelle formation. Although quite useful, the library of structures accessible is limited to only a few simplistic geometric configurations that are suboptimal for complex applications. It is believed that other physical phenomena like hydrogen bonding and electrostatic interactions can be exploited to complement hydrophobic interactions allowing for the design of structurally complex, aggregated micelles. To test this theory, ABC triblock peptide amphiphiles comprising an application-specific peptide, a zwitterion-like peptide, and a hydrophobic lipid were synthesized for which block sequence modifications and order changes were used to investigate their impact on micelle formation. The results provide significant evidence that both hydrophobic and electrostatic driving forces influence the formation of complex micellar structures. Specifically, hydrophobic self-assembly facilitates individual micelle formation, whereas dipole electrostatic interactions govern the association of micelle units into complex architectures. Initial results indicate that there exists considerable flexibility in the choice of application-specific peptide allowing these structures to serve as a platform technology for a variety of fields.
Keywords: block material; electrostatic interaction; pH-responsive material; peptide amphiphile; self-assembly; zwitterion.