This study involves the bottom-up design and tunability of responsive, amphiphilic peptide block copolymers which display unique pH-induced morphology transitions due in part to changes in the secondary structure of the peptide. Variations in the molecular architecture lead to diverse morphologies that have potential as drug delivery vehicles. Model systems for this study are based on hydrophilic blocks of poly(L-lysine) or poly(glutamic acid), with high peptide weight fractions. In order to tune the pH-response of these assemblies for drug delivery, the peptide alanine was incorporated into the hydrophilic block at various mole fractions, thus altering the local environment of the peptide chain. Light scattering and TEM were used to determine aggregate size and morphology as a function of pH, and circular dichroism (CD) spectroscopy was used to secondary structure within the peptide blocks. Drug release profiles were created to show the triggered release of doxorubicin with change in pH. This study demonstrates how controlling the molecular design and pH responsiveness of these assemblies is a potential handle to control drug release. 

Morphological tunability of pH-responsive, self-assembled polypeptide block copolymers through molecular design and polymer composition

245th National Meeting (2013)

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