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

In this paper, a kind of beta-amyloid peptide (Abeta1-16) conjugated gold nanoparticles (Abeta1-16@GNPs) are prepared and employed as colorimetric indicator for studying the interaction of beta-amyloid peptide with metallic ions (e.g. Zn(2+) and Ca(2+)). In the presence of Zn(2+), mono-dispersing Abeta1-16@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 Zn(2+) can interact with Abeta1-16 and form Zn(2+)-beta-amyloid peptide complexes. In particular, in the presence of Zn(2+), a time-dependent interaction of cells with Abeta1-16@GNPs has been observed that may suggest different expression levels of beta-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 Zn(2+), which gives further proof of the interaction mechanism.