Plasmon-Enhanced Fluorescence Based on Gold Nanobipyramids with PEG-Controlled Distance for Near-Infrared and Visual Analysis of Amyloid-β Aggregation.

The number of cases of Alzheimer's disease (AD) characterized by progressive amnestic syndrome is dramatically increased with population aging. It is urgent to detect and diagnose this disease early. The state of amyloid-beta protein 1-42 (Aβ) was commonly regarded as a hallmark for early diagnosis of AD. Here, a plasmon-enhanced fluorescence (PEF) sensor based on gold nanobipyramids (Au NBPs) was established for sensitive and visual detection of Aβ aggregation. Near-infrared (NIR) emitted boron-dipyrromethene (BODIPY) was employed as a fluorescent substance to obtain a 24-fold turn-on signal to recognize the state of aggregation of Aβ. The distance between BODIPY and Au NBPs was controlled by the length of polyethylene glycol (PEG). The obtained sensor was applied to real-time and sensitive detection of the state of Aβ by detecting the aggregation-dependent color transformation in human neuroblastoma (SH-SY5Y) cells. With the advantage of visual and dynamic detection of the cellular environment, the method can be employed to follow the progression of the Aβ protein and has promise as a robust diagnostic tool for AD.