Gelsolin Encountering Ag Nanorods/Triangles: An Aggregation-Based Colorimetric Sensor Array for in Vivo Monitoring the Cerebrospinal Aβ 42 % as an Indicator of Cd 2+ Exposure-Related Alzheimer's Disease Pathogenesis.

Nowadays, the environmental risk factors for Alzheimer's disease (AD) have received widespread attention. Two major amyloid-β peptide (Aβ) variants, Aβ 42 and Aβ 40 , play a pivotal role in the etiology of AD and the concentration ratio of which (i.e., Aβ 42 %) has been suggested to be the superior biomarker for AD. In this study, an "aggregation-based colorimetric sensor array" for the simultaneous identification and detection of Aβ 40 and Aβ 42 with structural similarity was established based on gelsolin-modified silver nanotriangles (Ag NTs) and silver nanorods (Ag NRs). Different aggregation behaviors of gelsolin-modified Ag NTs and Ag NRs in the presence of Aβ 42 and Aβ 40 resulted in different color and spectral changes, which could be quantitatively analyzed in terms of unique spectral patterns by principal component analysis. With the colorimetric sensor array employed here, the fluctuation of Aβ 42 % in different brain regions of rats exposed to Cd 2+ could be directly monitored. The downward trend of Aβ 42 % accompanied by variations of other biochemical indicators suggested that subchronic Cd 2+ exposure possibly triggered the onset of AD through the intervention of lipid peroxidation pathway. Furthermore, in vivo monitoring the downtrend of Aβ 42 % in cerebrospinal fluid (CSF) could also be realized, which offers a great opportunity for early diagnosis and treatment of AD that may be induced by environmental factors with CSF Aβ 42 % as a reliable indicator.