Dot-blot sandwich immunoassay with silver signal enhancement for simple amyloid beta protein fragment 1-42 detection

Abstract

Amyloid beta 1-42 (Aβ1-42) is a key pathophysiological hallmark of Alzheimer’s disease (AD). Changes in biofluids of Aβ have been associated with AD risk. Herein, a dot-blot sandwich immunoassay was developed for simple detection of the Aβ1-42 using gold nanoparticles as signal label. The results were easily observed by naked eye, and an image processing program provided semi-quantitation. Furthermore, addition of silver enhancer to the assay further improved sensitivity of the measurement. The proposed assay for Aβ1-42 had a linear range of 1–200 µg/ml, with a detection limit of 1 µg/ml and 0.3 µg/ml by naked eye and calculation, respectively. Performance of the developed assay was assessed in analyses of spiked plasma samples. The recoveries of Aβ1-42 were in the range of 112–158%, indicating that the developed assay is practical and reliable. The proposed method provides a low cost and simple assay for Aβ1-42 measurement.