Site-specific adsorption of gold nanoparticles coated with thermo-responsive peptides

A thermo-responsive elastin, elastin-like peptide (ELP)-gold nanoparticle (AuNP) hybrid (ELP-AuNP), was successfully prepared via the in situ reduction of HAuCl4 in the presence of lipoic acid-terminated ELP: (VPGVG)(4) (V: valine, P: proline, G: glycine) synthesized using a solid-phase peptide synthesis method. The conformation and aggregation properties of the ELP-AuNP in an aqueous buffer solution were examined using circular dichroism (CD) and ultraviolet-visible (UV-Vis) spectroscopies and transmission electron microscopy (TEM) observation. The phase transition of the ELP layer at the periphery of the AuNP because of the conformational change from random coil to beta-turn structures was found to proceed gradually with increasing temperature and to simultaneously cause an aggregation of the ELP-AuNP because of the component's hydrophobic interactions and a color change of the solutions from red to violet. The ELP-AuNPs were aligned selectively onto patterned, hydrophobic polystyrene stripes on a glass plate when the plate was immersed and incubated in the solution containing the ELP-AuNP above its phase transition temperature, as verified using atomic force microscopy (AFM) and scanning electron microscopy (SEM).