Water-soluble compound for detection of beta-amyloid

A method for detecting the presence of beta-amyloid plaque in a sample, the method comprising:

• contacting the sample with a compound represented by Chemical Formula 1 or a pharmaceutically acceptable salt thereof;
• and
• measuring an increase or shift in a fluorescence signal generated by the compound of Chemical Formula 1 upon binding to the beta-amyloid plaque:
• in Chemical Formula 1,
• Y is S or O,
• A is phenylpiperazine, N-methylaniline or N, N-dimethylaniline,
• R1 and R2 are each independently hydrogen or a C1 to C10 alkyl group,
• x is an integer of 1 to 10, and
• n and m are each independently an integer of 0 or greater, and n+m≥1,
• wherein the increase or shift in the fluorescence signal, as compared to a fluorescence of the compound in the absence of beta-amyloid plaque, indicates the presence of beta-amyloid plaque in the sample.