Gold nanoparticle-based colorimetric sensor for studying the interactions of β-amyloid peptide with metallic ions

In this paper, a kind of β-amyloid peptide (Aβ1–16) conjugated gold nanoparticles (Aβ1–16@GNPs) are prepared and employed as colorimetric indicator for studying the interaction of β-amyloid peptide with metallic ions (e.g. Zn2+ and Ca2+). In the presence of Zn2+, mono-dispersing Aβ1–16@GNPs enable to form aggregates or attach on the SHG-44 (human glioma cell) cellular surface which results in significant color change of the solution. The experimental results indicate that Zn2+ can interact with Aβ1–16 and form Zn2+–β-amyloid peptide complexes. In particular, in the presence of Zn2+, a time-dependent interaction of cells with Aβ1–16@GNPs has been observed that may suggest different expression levels of β-amyloid peptide related proteins in various cell cycles. In addition, the aggregating/binding process can be easily reversed by adding EDTA, a good chelated ligand of Zn2+, which gives further proof of the interaction mechanism.