Temperature dependence of conjugation of amyloid beta protein on the surfaces of gold colloidal nanoparticles.

The absorption spectrum of the amyloid beta 1-40 peptide (Abeta(1-40)) conjugated to gold colloidal suspension of 15, 20, 30, and 40 nm size were examined under temperature ranging from 5 to 50 degrees C. As the pH was externally altered repetitively between pH 4 and 10, Abeta(1-40)-coated 20 nm gold colloid nanoparticles exhibited a reversible color change at the entire temperature range tested in this study except for 5 +/- 0.2 degrees C.

Microscopic investigation of reversible nanoscale surface size dependent protein conjugation.

Aβ(1-40) coated 20 nm gold colloidal nanoparticles exhibit a reversible color change as pH is externally altered between pH 4 and 10. This reversible process may contain important information on the initial reversible step reported for the fibrillogenesis of Aβ (a hallmark of Alzheimer's disease). We examined this reversible color change by microscopic investigations.