An activatable small-molecule fluorogenic probe for detection and quantification of beta-amyloid aggregates.

Area of Science:

• Neuroscience
• Medicinal Chemistry
• Biochemistry

Background:

• Extracellular accumulation of beta-amyloid (Aβ) peptides in the brain is a key pathological feature preceding Alzheimer's disease symptoms.
• Developing sensitive and specific methods for detecting Aβ aggregates is crucial for early diagnosis and therapeutic intervention.

Purpose of the Study:

• To design and synthesize novel benzo[d]thiazole-based small molecules for detecting amyloid-beta aggregates.
• To evaluate the binding affinity, fluorescence properties, and biological characteristics of the synthesized compounds.

Main Methods:

• Structure-activity relationship (SAR) studies were employed to design two series of compounds: donor-acceptor (D-A) and donor-π-acceptor (D-π-A).
• Binding affinity assays were performed to assess the selectivity of the compounds for Aβ aggregates over other proteins and Aβ monomers.
• Fluorescence spectroscopy was used to evaluate the detection capabilities, and cytotoxicity and biological stability were assessed. Cell staining was performed on SK-N-BE(2) cells.

Main Results:

• The optimized compound BPM1 demonstrated the highest binding affinity to Aβ aggregates.
• BPM1 exhibited a 10-fold fluorescence enhancement upon binding to Aβ aggregates, enabling specific and sensitive detection.
• BPM1 showed low molecular weight, low cytotoxicity, excellent biological stability, and could fluorescently label Aβ aggregates in cells.

Conclusions:

• Benzo[d]thiazole-based compounds, particularly BPM1, are effective fluorescent probes for the specific and sensitive detection of amyloid-beta aggregates.
• BPM1 holds promise as a valuable tool for Alzheimer's disease research due to its favorable properties and cell permeability.