Interactions of Polyproline II Helix Peptides with Iron(III) Oxide

Interactions of a peptide with polyproline II helical secondary structure with maghemite (iron(III) oxide, Fe2O3) surfaces were characterized using a variety of surface techniques. A quartz crystal microbalance with dissipation was used to measure the hydrated mass and thickness (92 +/- 29 ng/cm(2) and 0.89 +/- 0.27 nm, respectively) of a layer which formed after a sensor coated with Fe2O3 was exposed to the peptide in aqueous solution. The analysis revealed that the peptide formed a stable thin layer on the sensor. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy of the monolayer were employed to study the relationship between the metal and the peptide. Finally, Fe2O3 nanoparticles were incubated with the peptide, and analysis of the settling and particle size revealed that the presence of the peptide reduced the occurrence of large aggregates in solution.