2 styrylpyridazine 3 2h one were determined by comparing each fluorescence intensity before and after being mixed with agglomerated a u03b240 peptide 10 u03bcm 35 u00b0 c agglomerated in pbs buffer for 3 days nine compounds compounds nos 14 15 17 18 19 20 25 27 28 exhibited an increase in the fluorescence intensity of 10 times or more in the emission spectrum which means that the compounds were bound with a u03b2 aggregates table 2 apparent binding constants k d of the nine compounds were measured by using 10 u03bcm aggregated a u03b240 peptide fluorescence intensity of respective probes of 01 0 5 1 25 5 and 10 u03bcm dissolved in pbs and fluorescence intensity of a mixture with aggregates a u03b2 peptide were measured compound 14 fig1 a and 1b had the highest affinity with respect to a u03b240 k d 1 84 u03bcm theoretically a preferable fluorescence probe for a u03b2 aggregates should have high fluorescence reactivity and binding affinity fluorescence properties of the fluorescence probe are significantly changed as the probe is bound to the a u03b2 peptide and this means that it is u2018 turned on u2019 according to an interaction with a target the compound 14 was particularly excellent by detecting a u03b2 with fa u03b2 f0 40 84 and k d 1 84 u03bcm fluorescence imaging of compound 14 was performed on intracellular a u03b2 aggregates of a shsy5y neuroblastoma cell in order to measure intracellular uptake and aggregation of a u03b2 1 u03bcm of a u03b242 fitc a u03b242 labelled with fluorescein isothiocyanate was added and shsy5y cell was cultivated 3 days and imaged with fluorescence microscope uptake.