Synthesis and evaluation of curcumin-based near-infrared fluorescent probes for detection of amyloid β peptide in Alzheimer mouse models

The abnormal accumulation of amyloid β protein (Aβ) is one of the most important causes of Alzheimer's disease (AD) and is usually a detecting biomarker. Curcumin and its derivatives have potential Aβ aggregate targeting ability; we synthesized a series of curcumin-based near-infrared fluorescence probes in this study. By characterizing the excitation wavelength and emission wavelength, the imaging characteristics of the investigation in the near-infrared light region were determined; with an increase in the concentration of the probe compounds, the fluorescence intensity showed an upward trend, demonstrating ideal optical characteristics. In vivo, imaging results showed that the synthesized probe compounds could penetrate the blood-brain barrier (BBB) and specifically bind to Aβ in the brain of APP/PS1 mice. Especially for compound 3b, the maximum emission wavelength was around 667 nm, and the fluorescence signal intensity in the brain of the APP/PS1 mice model was more than twice that of the wild control group at 120 min after administration, which could display Aβ pathological changes. The fluorescent probes designed in this study can become an effective tool for early AD diagnosis and visual detection.