Localized Supramolecular Peptide Self-Assembly Directed by Enzyme-Induced Proton Gradients.

Electrodes are ideal substrates for surface localized self-assembly processes. Spatiotemporal control over such processes is generally directed through the release of ions generated by redox reactions occurring specifically at the electrode. The so-used gradients of ions proved their effectiveness over the last decade but are in essence limited to material-based electrodes, considerably reducing the scope of applications. Herein is described a strategy to enzymatically generate proton gradients from non-conductive surfaces. In the presence of oxygen, immobilization of glucose oxidase (GOx) on a multilayer film provides a flow of protons through enzymatic oxidation of glucose by GOx. The confined acidic environment located at the solid-liquid interface allows the self-assembly of Fmoc-AA-OH (Fmoc=fluorenylmethyloxycarbonyl and A=alanine) dipeptides into β-sheet nanofibers exclusively from and near the surface. In the absence of oxygen, a multilayer nanoreactor containing GOx and horseradish peroxidase (HRP) similarly induces Fmoc-AA-OH self-assembly.