Self-Assembly of a Model Peptide Incorporating a Hexa-Histidine Sequence Attached to an Oligo-Alanine Sequence, and binding to Gold NTA/Nickel Nanoparticles

Amyloid fibrils are formed by a model surfactant-like peptide (Ala)10-(His)6 containing a hexa-histidine tag. This peptide undergoes a remarkable two-step self-assembly process with two distinct critical aggregation concentrations (cacs), probed by fluorescence techniques. A micromolar range cac is ascribed to the formation of pre-fibrillar structures, whereas a millimolar range cac is associated with the formation of well defined but more compact fibrils. We examine the labelling of these model tagged amyloid fibrils using Ni-NTA functionalized gold nanoparticles (Nanogold). Successful labelling is demonstrated via electron microscopy imaging. The specificity of tagging does not disrupt the ?-sheet structure of the peptide fibrils. Binding of fibrils and Nanogold is found to influence the circular dichroism associated with the gold nanoparticle Plasmon absorption band. These results highlight a new approach to the fabrication of functionalized amyloid fibrils and the creation of peptide/ nanoparticle hybrid materials.