A Self-Assembled Nanofiber Catalyst for Ester Hydrolysis

Catalytic particles based on supramolecular systems have demonstrated significant improvement in the field of catalysis. In this work, histidine-functionalized self-assembling peptide amphiphiles (PAs) were synthesized in order to form self-assembly high-aspect-ratio nanofibers with internal order that can present imidazolyl groups capable of ester hydrolysis. Self-assembly of the molecules making up the catalytic particle was studied by transmission electron microscopy and circular dichroism. The reactive sites were designed with histidine residues to catalyze the hydrolysis of 2,4-dinitrophenyl acetate (DNPA). Enzymatic hydrolysis of DNPA was observed in the presence of the nanofibers by UV−vis spectroscopy and the Michaelis−Menten enzyme kinetics model. Significantly faster hydrolysis rate was observed in the presence of self-assembled nanofibers relative to spherical aggregates expected to have less order as well as single molecule catalysts.