β-Amyloid (1-40), FAM-labeled, is a β-Amyloid (1-40) peptide tagged with a FAM fluorescent label, exhibiting an excitation wavelength (λ ex) of 492 nm and an emission wavelength (λ em) of 518 nm.

The transport of fluorescently labeled Aβ42, both FAM-labeled and Fluor 488-labeled Human β-Amyloid (1-42), as well as scrambled Aβ42 (FAM-labeled scrambled β-Amyloid (1-42)), across an endothelial monolayer, is analyzed in an in vitro blood-brain barrier (BBB) model, utilizing transendothelial electrical resistance (TEER) to monitor changes over time (specifically over 120 minutes, with or without the presence of Aβ24). It's observed that the presence of Human β-Amyloid (1-24) at a concentration of 1 μM results in the retention of H-Aβ42, which impairs its efflux from the BBB, thus hindering the molecule's effective clearance. When FAM-labeled or Fluor 488-conjugated H-Aβ42 is applied to the apical side of the cell inserts, it demonstrates successful cross-BBB migration, unlike the FAM-labeled scrambled β-Amyloid (1-42), which does not efficiently cross.