APP and Alzheimer disease: Particularly, probe 9 hold great potential to discriminate 6-month-old (predominant soluble Aβ species) or 10-month-old (predominant insoluble Aβ species) APP/PS1 AD mice from age-matched WT mice, with signal intensity ratio of APP/PS1 AD mice to WT mice being ~1.5 and ~1.7 at 10 min respectively.