Studying copper(ii) ion induced interactions of β-amyloidpeptides within living cells by gold nanoparticleprobes

Abstract

In this paper, a kind of gold nanoparticle (GNP)-based colorimetric assay was developed for studying copper(II) ion (Cu²⁺) induced interaction of β-amyloid (Aβ) peptide with living cells. In the presence of Cu²⁺, biotin modified β-amyloid peptides (Aβ_1–16(biotin)) enable to attach on the SHG-44 (human glioma cell) cellular surface which results in significant color change of the cells when the indicators, streptavidin conjugated GNPs were introduced into the reaction mixture. We also demonstrate the assay ability to screen Aβ aggregation inhibitors because the aggregating/binding process can be easily reversed by adding chelators (e.g., EDTA, EGTA, histidine and clioquinol) of Cu²⁺ to the system. In addition, a time-dependent interaction of SHG-44 cells with Cu²⁺ and Aβ_1–16(biotin) has been observed that may suggest different expression levels of Aβ related proteins in various cell cycles.